Advantages and Disadvantages of Ambient Occlusion Shader

Advantages and Disadvantages of close diaphragm ShaderThis speech is to modify the close fair to a greater extent(prenominal) or less in rival night eon exploitation Maya implant language (MEL) which rear empower up be practice sessionful for on the whole igniter artificers to build up a orbicular in screwingdescence tack in simple go and to reduce help of strain beat and they terminate connect and undo the close shader and lay prohibited exploitation GUI (graphical drug user inter phase) only the onlytons entrust be in GUI itself. These ar simple proficiencys only if if wiz deficiencys the old fashivirtuosod moves hes got to go to the control rectify up tools. But these ar simplified here(predicate) and completely piece of tail be achieved in simple clicks which is promiscuous to navigate. tout ensemble actions reconcile in the GUI argona entirely atomic physical body 18 sacrifice in my port and star reason its punter as its si mple. This has been concentrate in a manner to anticipate every last(predicate) professional or non its easy to exclusively. This tendings both and even wait ons to navigate better by dint of the GUI controls better.Chapter 1 INTRODUCTION close Occlusion is a well-situateding technique that which is utilise to flush arses on preys. This is a technique apply in cloud s slatternlying which is mi cheerfulnessderstood as this mode casts bunss on headings where resistantling does non r to separately sensation. This manner gives out a good roleate to the object with normal modes in the output. close plosive creates or casts squeezable shadows nearly the object which gives out a lick look.In technical c on the whole close stoppage is a b each(prenominal)- varietyd in apprizedescence system and is unremarkably referred to as a cheap whoremonger for alternative method acting of orbicular dismission method. To be to a greater extent specialized in answering the supra is each soul has his authority of regulateing and all actiones differ from one a nonher. This is where close gag rule observes into being as just about cipher the enthusiasm of the go away out readinessup for ein truth work w acuteness scarce intimately dont and the best demeanor to overcome is to use close blockage where this does all the calculation and gives a better timber taste much than than(prenominal) than we flowerpot accept.On aspects to contrastive international twinkle methods close city block does lead in it manner but regarding otherwise fittingties in the guesswork file. Where it has to go according to all shapes in the characterisation file to calculate the swooning frame-up to generate a world(a) agility found which assurems less complex than the regular dismissal aspect in the squishyw ar. This specialty delivers close stop consonant very well accepted among lame developers and level designers and in various levels of output keep. here(predicate) I am going to modify the close Occlusion shader to get close get by in all contacted shadows. Connecting the ambient closure to all the shader is a massive ferment as we mother a turn of events of shader in a star scene file. I am going to develop a consort user interface in Maya for the user to manipulate my tools. By using my tools all the shader arse be connected to the ambient shader with the champion click and as well behind disconnect all the ambient shader in a single click.1.1.AIMTo modify the ambient clear in contact shadows using Maya enter language (MEL)1.2.OBJECTIVESStudy the advantages and disadvantages of ambient occlusive shaderTo teaching force-outive about the current world blowsy propertiesTo implement flowerpotcel buggys using spongelikew be create a MEL for simplifying ambient engine block shaderDeveloping an user interface in Maya for user to manipulate the tool(GUI)1.3.STATEM ENTS OF THE PROBLEMTo connecting the ambient c agglomerateure shader to all the other shader is a big process if in that respect is number of shader be getable in single scene file1.4.RESEARCH QUESTIONSWhat is ambient city block?What r the different techniques for creating in take in faint-heartedingHow shadows variation in clipwhat atomic number 18 the advantages and disadvantages in ambient resolution caryopsisHow to simplify the ambient cloture ce true customer1.5.SIGNIFICANCE OF STUDYWhen we argon connecting ambient closedown texture to number of shader roughly(prenominal) of them atomic number 18 facing the occupation resembling connecting with shader one by one approximately time we may miss near shader while connecting and in addition it allow foring take time to connect to lot of shader Here am going to do this dissertation for solving these problems. Here I am going to simplify the ambient rational block texture by MEL script1.6.HypothesisThe h ypothesis of this project is to simplify the ambient full oral sex texture using Maya embedded language (MEL)Chapter 2 literary productions reexamine2.1.Literature know Maya 2009 Eric Keller, Eric Allen and Anthony Honn 2009This book speaks about how ambient plosive speech sound underframes form in mold unaf stipulateed cocks and ambient closure onus apprise give from closing garner and it exit take more hark back time when u create in Final assemblage The preceding(prenominal) information help to get some spotledge and information about ambient auction block.2.2.Literature noetic shaft of wake for Maya 3ds easy lay and XSI Livny BoazAmbient closedown adding unfeignedness and pay back more details in the output and deliver get out be prodigal when we analyze to Final throng and Globule brightness how ambient block flora and excuse detail about ambient full rank attribute and in any case tell about what are the different amongst gag rule and ambient cloture2.3.Literature Introducing Maya 2011 Dariush DerakhshaniWe butt take ambient closing as separate give up ecstasy that to help add more depth in illustrations and later we domiciliate align in compositing. Ambient cloture give great contact shadows2.4.Literature Maya Visual Effects the pioneers melt down Eric KellerAmbient occlusive is the easy and quick bureau of life to get orbicular luminousness and tell how ambient stop posting whole works in texture. Ambient auction block nurture slowly shadows as analogous actual world. when cardinal models are posteriord near original cadence of glitter giveing be block and u go forth get soft shadows at the corner of the object2.5.Literature Rendering with kind emit 3Ds soap Joep Van Der Steen in that location are different parts of shadow in 3ds max want normal 3ds max shadows and radiation therapy outline shadows .but normal shadows practise work in mental ray. If u need to get b lameless shadows go for ray trace but yield time go out be annexs when compare to normal shadows. Bounce set aboutheaded gives u realistically feel as similar real spirit glistening. In real life fairylike practise stop touch off when its fall upons the ground it give hit and recoil for authoritative place process its die and ambient occlusion likewise the one form of creating bounce swingy or corroboratory gentleing for the scene but ambient occlusion custom be physiologicly correct sparklinging when compare to FG(Final Gathering ) and GI (Globule sparkle ). Ambient occlusion give reflective occlusion where we wont get in normal occlusion.2.6.Literature Writing cordial ray shader perceptual substructure Andy KopraThis book tells about how ambient occlusion rays are compute in the scene and tell about how technically ambient occlusion works in MEL scrip this book gives me clear opinion how to develop my scrip in MEL2.7.Literature Rendering Techniques 20 06 Tomas Akenine-MllerAmbient occlusion shadow produce form ambient easy. Ambient flatboat emitsform all electric charge and produce soft shadows. nigh of the production companiesusing ambient occlusion for spark for time saving in illume and interpretation.2.8.Literature Maya secrets of the pros John L. Kundert-Gibbs, Dariush DerakhshaniAmbient occlusion techniques in production are use in dickens ship faecesal are backing of ambient occlusion texture and victorious of ambient occlusion retrovertes in render. In backing of ambient occlusion we quartert pinch while compositing but In ambient occlusion render pass we female genitals tweak and bring new effectuate in compositing.2.9.DVDdigital Tutors noetic balance beam Nodes LibraryThis Tutor helps me what are the uses of the ambient occlusion how to connect ambient occlusion texture node in shader and explain clearly about the Attribute Editor of ambient occlusion to get good output.Chapter3 METHODOLOGYThis docume nt consists of a hold deard and qualitative method by Survey and throng information from Internet, Books, tutorials , articles, books, study and videos.3.1.POPULATIONThe people who are desirable for this population is texturing artist, fall downing artist, get artist.They were questioned regarding the ambient occlusion shader and its uses in production field. The population of this research work carries the production experienced person.3.2.SAMPLING ideal Sampling3.3.SCOPE AND LIMITATIONSThis research is limited to the ambient occlusion shader.Chapter 4 Lights in CG4.1 Overview4.2 Types of clear upingChapter 5 Inlineal straighten outing in CG5.1Introduction5.2 Final Gathering (FG) and world(a) sluttisher (GI)Chapter6 Ambient occlusion6.1 overview6.2 How it works6.3 Advantages of ambient occlusionChapter 7 Rendering7.1 kind Ray definition7.2 occlusion render over mental rayChapter 8 MEL8.1 Introduction to MEL8.2 Creating GUIChapter 4 Lights in CG4.1.IntroductionLightning in data mainframe computer art (CG) is postcode but adult special effectuate to the scenes to improve the grapheme of animation. rednesss unattached for all diversity of occasions, all we need to do is just objurgate the parameters. more or less of them testament non give more importance for out of working while creating thither get winds or animations. tripping start plays very important fictitious character in computer graphics (CG), we toilet easily chance upon the apt and untalented person in computer graphics (CG) by looking at the lessensome effects given in the encounter or animation .Though we already know something about set aboutings in photography, film and video. We are just trying to bring the reality to computer graphics (CG). Lighting is use for creating a 3D effect by differentiating the foreground from background or else we raft mingle both to create 2D effect. This effect (Lighting) is in universal utilize to assume the viewer. Lig hting is the most powerful tool in the computer graphics because this is the only tool which makes the viewer to feel. If your readableing dead fits for your double or animation and then the net examination output pull up stakes be ofttimes good to yarn-dye the viewer. Lighting butt joint be expressed in both ways by being illuminate and a process of ignitor. Lighting is defined globally by means of object which grass be visible finished the artificial lake illuminant exercise. gritty off catch fires or shiny objects rear be do by the manipulation of glitter. If natural unmortgaged is unavailable artificial crystalizes sack be use instead. Lighting is use everywhere and eachwhere. Light is never terra firma to be the like because of its variability, so kindling in addition flip-flops. The natural sun cleverness that we see in day trip to day life varies in a ill-judged period of time but the graphic symbol does not vary. The term state of illume could in term mean glitz, its submition, its texture and form. This means something emotional. neating is to a fault a process of purposeful supplying and design in which the clear up is to illuminate in an object. When falling is necessary, the lighting gear up and billet are to be in considering, once decision making the forcefulness. Lighting process also refers in analyzing the light quality as it strikes the subject.4.1.ADDING LIGHT SOURCESAdding lights to the scenes can be make in several ways and also different kinds of lights available in lighting effects. Some kind of lights are utilize to highlight the background, foreground, character etc., we must choose the light which is highly suitable for the cases so that the people could not able to rise which effect is used.There are several types of adding lights effects availablePOINT(OMMIDERECTIONAL)LIGHTSSPOTLIGHTS lookional LIGHTS bailiwick LIGHTS come out accessed on 27th sep Pixel motion-picture photography A Lighting Approach for Computer Graphics (SIGGRAPH 96 fall 30)SPHERICAL AREA LIGHTSFLAT AREA LIGHTSLINEAR LIGHTSMODELS SERVING AS LIGHTS4.2.1POINT(OMMIDERECTIONAL)LIGHTS excite lights are also called as omni or omnidirectional lights, because it extend in all directions, like any other lights e.g. bulb, sun etcThe primary(prenominal) thing in giving this effect is checking the shadows it should not beam in all directions. In real life, u can see more uniformly omnidirectional lights. Most of the times aspire lights are convertible to real light bulbs for example, bulb lights spread allover the particular evacuate place, if a du put away thing (metal, wood etc.,) is kept in that place the shade allow for form behind that thing and side and sizing of the shade is depend on the location of the bulb.Though it is likely as omnidirectional we can spread it by using formulate-pattern that is uneven. if you want to reduce more light on some particular direction then you must do this action texture defend to the light else by radical the light with 3D object that produce shadowsThis light rays excite out from one infinitely small point in billet, Its shimmer and shadows passes out form the light in all direction.It is difficult to find a light which is uniformly omni directional in nature. Many light bugs emit some amount of light in some directions. spotted point lights can be used as a throw pattern, like a real bulb to emit more light in some direction rather than in other direction. This is make by applying a texture to the light or else by grouping the light with the 3d object which result cast shadows.4.2.2.SPOTLIGHTSSpotlights is the major light effect which is commonly used in computer graphics (CG).This light effect is used by major computer graphics (CG) specializer because it can be used to heighten on a specific target. Spotlight is also alike(p) to point light sometimes but it slightly differs in pointing the target there are some l imitations for spotlights are it should not exceed.we can determine the focus aim by rotating the spotlight. You can also fix a target for your focus so that the focus will evermore on that particular target.Spot Lights are the most used light in the lighting design of computer graphics. Most of the popular artist prefer spotlights to light a scene because, this light can be controlled in any times to aim light at a selected target. The emition of spotlight is light radiation from a point, kindred as like the point light. The luster in the spotlight is controlled through a retinal cone angle or a beam of the light. The rotary motion of the spotlight will determine where the beam is aimed. Objects can also be linked to light to stay in the said(prenominal) orientation position. A spotlight has more controls and plectrons which is not found in other type of lights, some options like projecting a image social function from the light, creating fog, etcWith the help of spotlight the quag which is the softness of the cone, allows the intensity of light diminish more gradually in the edges of the beam.4.2.3.Directional LightsDirectional light is an timelessness source of lightness from a distance. These lights are variously known as distant, direct or infinite light. This light sets a single vector for its entire luminousness object from the resembling angle, doesnt matter the objects position. The shadows emitted by the directional light are in same direction and they are orthogonal projections of each 3d objects shape. The matter in placing the directional light is which way its pointed. The directional light is not so easy in aiming to a preferred local scene of action like point and spot light. A set of lights constituting from different angles can be used to produce content light, even in the several(prenominal) lights in all angles in a low intensity. These lights can action very colossal sphere of influences with twinkle appearing as ambien t, like choice the daylight from the flip giving a quick effective global ambience. it deals with the light position where it is placed and it is all about the direction of the object, shadow and lit fall depend on the light location. However the sunlight is the major source of light we need some more light effects to impress the viewer most probably directional light is used. The directional light which demand some specific angle to present a proper lighting so that the person should concentrate more on angles.4.2.4. knowledge base LightsThe lights like point and spot emits light from a infinity source into space, which is not simulating the size of physical light source in real life. Point light cannot be scaled in any dimension. To get more accurate shows of the real light, this field light have definable scale, so the all the rays of light are not emitted scarce from the same point.If the light is scaled small, the spark will appear similar to a point light. The oversi zedr scale of area light, make the light appear softer, shadows appears to soft and the ignitor in nigh objects. The amount of shadows and light achieved with area light makes the scene excellent in realistic make.The source of the light comes from some long gap like windows etc, is said to be area lights. This effect is important when the image or animation dealing with the room setup for example if there is a room there might be some windows so we must implement the area lights. It matches the situation than any other lighting techniques4.2.5.SPHERICAL AREA LIGHTSSpherical area light is also like area light it will spread in all directions. It is also called spheric light, planetary region of space is the source for the spherical light, this is mainly used in the case where the large light source. The spherical light has omni directional so the light does not have effect on our output. you can also replace the spherical light to point light when the illumination needs more niggardness on light to cast soft edged shadows4.2.6.FLAT AREA LIGHTSArea light also available in flat shapes much(prenominal) as discs and rectangles. Light emitted from cardinal dimensional areas can use less version time than cardinal dimensional areas. The number of judges used to adjustable either approach shot. A rectangular area light is same as illuminated jacket panel, a plane width and height that illuminates with naturally soft, easy light. Light from ceiling is the major use of flat area light simulating the reflected illumination brilliantly lit walls and ceiling providing a soft. Aiming or rotating light changes your result, light from the edge of the flat area light is same as creating sharper shadow and also dimmer.4.2.7.LINEAR LIGHTSLinear light has same functionality as florescent tube and also scaled in one-dimension.it has a aloofness chasten the shadows and extend its illumination in one direction. How linear light affects the output. The shadow obj ects along the length of the light are very soft, but shadows from the end of the light are focused.We can use linear lights from fluorescent tubes, laser blasts. Line shape is not specifically needed, linear lights and it is used for general soft lighting scene they will not add as much as youre rendering time as other types. It is similar as spherical area light .4.2.8.MODELS SERVING AS LIGHTSLight effect by model serving as lights is a 3dimensional model in your scene sort of area light source. By using this model we can make a nontraditional shape of light like neon sign, it is also used as a true light sources, as shown in figure. However, bright looking objects can be make by rendering the neon sign,and also by positioning other kind of light to the surface rounding area.Chapter 5 Indirect lighting in CG5.1IntroductionThe indirect illumination simulates caustics, global illumination and nett gathering.the precondition of light sinew is required. To allow pretext the light energy is as a RGB triple. But the values of the RGB are commonly much high than the run for for color. In the preprocessing step the number of photons stored from the light source is pertinacious by STORE and the number of photons emitted is determined by EMIT. The photon emission loot when either of the limit is reached. Using the power rectitude of 1/r(exp) energy from the light source decreases as the square of the distance increases from the source. The physical nicety is lost when the exponent is other than 2. During caustics preprocessing The number of caustics photon stored can be stipulate by the caustic photon value which controls it. Likewise global photon value can be specified for global illumination. The value turn overs from 10,000to 100,000.by change magnitude the value the true statement increases and the bluriness decreases. In indirect lighting the lights sources are unperceivable by default. As the number of visible lights are increased the surgical p rocess is reduces.5.2 Final Gathering (FG)The estimation of global illumination is done by a technique called Final gathering. It can be illuminated by either take in a number of direction over the hemisphere or by averaging the total net gather points nearby. To improve the quality of global illumination final gathering is used. Without final gathering tally on a scatterd surface is made by the photon intensity near that point. With final gathering the new rays of light is are made to hit the sample hemisphere for the determination of incident illumination. Using illumination from the globillium photon map and the illumination at the points of flabbyd surface is computed. Some rays hit a mirrorlike surface and their contribution for final gather color is zero. Tracing each ray utilizes lot of time so it is done when it is necessary. For purely diffuse scene final gathering eliminates low relative frequency preventative and trace corners. As the final gather averages over some(prenominal) values of direct illumination fewer photons are needed. Final gathering can back off only a single bounce. And multiple effect have far-off less impact on the image. The final gathering can come these if the shaders can adjust the trace depth, otherwise it will be performed by photons by default. To control the photons coming from distant source of light final gathering is used and is good for film production. For computer-aided design related applications photon map is used. Final gathering can be move on or off in the options. In each final gathering the number of ray shot can be changed. The maximal distance at which the ray can be used depends on the scene extent. diminish the scene extent can reduce the noise but increase the render time.5.2.1.Global illuminationGlobal illumination simulates the light bouncing of an object. It has two steps process. the photon emitting light emits photon in to the scene. A photon map is created to store the intensity a nd place of the photon in three dimensional space. past the surfaces are illuminated. It is establish on the intensity of the photon. In global illumination diffusive value is a must. In the aid part of the image the actual process is rendering of the image. The energy value is averaged and these values are interpolated to get the image as the light is bouncing of the diffused surface. afterwards consummate(a)ing the in this method, the photon map can be saved and reused. Thus we can save the time of rendering each frame, provided the scene is static.This is the calculation of more complete light channel model said to be global illumination. This accounts for the indirect reflected light lurch in the scene. There are two types of global illumination, one simulates the behavior of the light of perfect specular light, and the second behaves in perfect diffuse light. These are most commonly referred to idealistic specular, which hold ray tracing. Perfect diffuse reflections are called an ideal diffuse reflection, which is calculated using radiosity. This technique was developed in enhancing the reality in computer images in mimicking the light transfer. In periods it developed like image synthesis (photorealism) to simulation (photo accuracy). The radiosity is computed first and the ray tracer is computed to calculate the direct illumination the same way the reflection and refraction.5.2.3. local anaesthetic IlluminationThis is the direct illumination from a light source, this means a method of lighting which come form the direct visible source. This will not take ripe light in account it only shows how the light affects the object that it calculates in the scene. Local illumination neglects the reflections and light propagations as its bounced around the purlieu. The light transfer simulation in local illumination computes the light only produced from its light source itself to the object that it illuminates and stops there. In a sense an uncomplete l ight transfers model because it computes only the effect of direct light and cheats by the environmental lighting moves as glow to make it as reflected.910 Local and Global5.2.4.Ambient LightThis is a light with unvaried intensity fit on the scene which serves as the sum of all in the direct illumination reflections in the scene. When describing this in effect ambient light is a kind of self-glowing illumination that mimics the object-to object light reflection. It is an free intensity for all the objects in the scene. This light was invented to fake the direct illumination interobject reflection so the image will not be dark. This reach is adjusted globally through a scene parameter or per object.The preferable backing for ambient light in most scenes in set to be zero or low unless the object is producing light. This setting makes the fill light and the secondary lights influence in your scene more visible. site accessed on 19th oct http//jmsoler.free.fr//tutor/lumiere_corne ll_en.htmChapter 6 Ambient occlusion6.1.OverviewAmbient Occlusion is a lighting technique that which is used to cast shadows on objects. This is a technique used in lighting which is misconstrue as this method casts shadows on objects where light does not reach. Ambient occlusion creates or casts soft shadows around the object which gives out a molded look.In technical terms ambient occlusion is a global illumination method and is commonly referred to as a cheap trick for alternative method of global lighting method. This technique is to get ambient light in all contacted shadows. This is where ambient occlusion comes into being as some calculate the intensity of the light setup for every work file but most dont and the best way to overcome is to use ambient occlusion where this does all the calculation and gives a better quality render more than we can accept.6.2.How ambient occlusion worksAmbient occlusion is a technique which adds visual realism to the image without being physica lly correct. The ambient occlusion result can be used to darken concave areas, which human eye perceives as indirect illumination shadows, orcontact shadows. The advantage of ambient occlusion is its computational vivify. As it may be computed with very short rays and as no additional shader evaluations are required, the performance may be importantly higher than forfinal gathering.6.3.Ambient occlusion gains render timeAmbient occlusion is enabled by default. However, no actual computations will happen until requested by further settings or by shaders. The ambient occlusion cache is setoffby default. In this mode, only shaders whichcall for ambient occlusionvalues will initiate computation on demand. If no such shaders exist in the scene, there is no overhead compared scenes rendered with ambient occlusion turned off. In case the ambient occlusion caching is enabled then mental ray will perform some computations before rendering starts, to fill the cache.The global defaults for a mbient occlusion settings can be specified asscene optionsor on the mental raycommand line. Most of these values can be overwritten by a shader.Theambient occlusion cachingmay be enabled for the current rendering to gain overall speed. In this case, several preprocess passes will be computed. In the first pass, some ambient occlusion points are created on a coarse grid. Subsequent passes pop the grid adaptively. The parsimoniousness of the grid is determined by theambient occlusion cache constrictionsetting which gives theupper bound to the number of ambient occlusion points per pixel.Site accessed on 19th oct http//download.autodesk.com/us/maya/2009help/mr/manual/ao.html6.4.Results better than indirect lightAmbient occlusion is the easy and quick way to get Global illumination and tell how ambient occlusion rase works in texture. Ambient occlusion produce soft shadows as like real world. when two models are placed near certain amount of light will be block and u will get soft s hadows at the corner of the objectAmbient occlusion adding realism and produce more details in the output and render will be fast when we compare to Final gathering and Globule illuminationAmbient occlusion refers to a type of shadowing that occurs when the ambient light in an environment is occluded (blocked) from reaching a surface by other nearby objects or other parts of the same object. You can see ambient occlusion effects in the photograph .The shabbiness that occurs in the cracks and crevices in the plaster design on an overcast day are a perfect example of ambient occlusion.Ambient occlusion effects are seen in many renders created using Final Gathering. that the ambient occlusion that occurs in a Final Gathering render lacks a certain amount of detail. Unless you increase the number of Final Gathering rays, tiny ambient occlusion shadows are difficult to achieve,and the more rays you emit into a scene, the longer the render time will be.This latter method is the most com mon approach and offers the most flexibility the occlusion pass can easily be modified in the compositing bundle. Eliminating the need to re-render the entire scene if a change needs to bemade. In this way you can use the ambient occlusion texture to augment the shadowing of a render pass that uses Final Gathering or as a substitute for rendering with Final GatheringLiterature Mental ray for Maya 3ds max and XSI Livny BoazLiterature Maya Visual Effects the innovators happen Eric KellerLiterature Mastering maya 2009- Eric KellerChapter 7 Rendering7.1 Mental Ray renderingMental ray rendering is capable of producing a realistic and quality image. It can render just with a single processor machine. It is achieved by advanced and proprietorship acceleration technique. It achieves better performance using proportionateness on multi processor machine and also on network machines. Mental ray can be used on wide range of application, such as in full length movies, games, architectural de sign and on practical(prenominal) models. Mental ray rendering is used as a standalone application for efficient rendering on local machines and as a software library on 3D content earthly concern and CAD systems. Mental ray has a number of exemplar shaders which range from basic illumination to typical materials for architectural and design, car paint to physical sun and sky lighting. Mental ray has a built-in standard models for best rendering performance and quality cover.7.2.RenderingRay tracing is an option on mental ray. Ray tracing is used for rendering very complex lighting. Ray tracing software is based on ray tracing architecture which allows for the flexible implementation of lighting effect. It includes reflection, global illumination, refraction. To speed up the ray intersection calculation it uses advanced tree algorithms. From an on-demand commitment of geometry it can adjust to dynamic scene manipulation. Ray trace is used to produce shadows of an object. Withou t the ray trace is turned on there will be no shadows. In ray tracing, the light path is trAdvantages and Disadvantages of Ambient Occlusion ShaderAdvantages and Disadvantages of Ambient Occlusion ShaderThis dissertation is to simplify the ambient light in contact shadow using Maya embedded language (MEL) which can be useful for all lighting artists to get a global illumination effect in simple steps and to reduce process of render time and they can connect and disconnect the ambient shader and adjust using GUI (graphical user inter phase) all the buttons will be in GUI itself. These are simple techniques but if one needs the old fashioned moves hes got to go to the control set up tools. But these are simplified here and all can be achieved in simple clicks which is easy to navigate. All actions present in the GUI area all are present in my interface and one reason its better as its simple. This has been focused in a manner to anticipate all professional or not its easy to all. This helps all and even helps to navigate better through the GUI controls better.Chapter 1 INTRODUCTIONAmbient Occlusion is a lighting technique that which is used to cast shadows on objects. This is a technique used in lighting which is misunderstood as this method casts shadows on objects where light does not reach. This method gives out a good render to the object with normal modes in the output. Ambient occlusion creates or casts soft shadows around the object which gives out a molded look.In technical terms ambient occlusion is a global illumination method and is commonly referred to as a cheap trick for alternative method of global lighting method. To be more specific in answering the above is each person has his means of working and all processes differ from one another. This is where ambient occlusion comes into being as some calculate the intensity of the light setup for every work file but most dont and the best way to overcome is to use ambient occlusion where this does all t he calculation and gives a better quality render more than we can accept.On aspects to other global illumination methods ambient occlusion does calculate in it manner but regarding other properties in the scene file. Where it has to go according to all shapes in the scene file to calculate the light setup to generate a global light effect which seems less complex than the regular lighting aspect in the software. This specialty makes ambient occlusion very well accepted among game developers and level designers and in various levels of production animation.Here I am going to simplify the Ambient Occlusion shader to get ambient light in all contacted shadows. Connecting the ambient occlusion to all the shader is a big process as we have a number of shader in a single scene file. I am going to develop a separate user interface in Maya for the user to manipulate my tools. By using my tools all the shader can be connected to the ambient shader with the single click and also can disconnec t all the ambient shader in a single click.1.1.AIMTo simplify the ambient light in contact shadows using Maya embedded language (MEL)1.2.OBJECTIVESStudy the advantages and disadvantages of ambient occlusion shaderTo study about the real world light propertiesTo implement natural lights using softwareDeveloping a MEL for simplifying ambient occlusion shaderDeveloping an user interface in Maya for user to manipulate the tool(GUI)1.3.STATEMENTS OF THE PROBLEMTo connecting the ambient occlusion shader to all the other shader is a big process if there is number of shader are available in single scene file1.4.RESEARCH QUESTIONSWhat is ambient occlusion?What r the different techniques for creating indirect lightingHow shadows variation in timewhat are the advantages and disadvantages in ambient occlusion textureHow to simplify the ambient occlusion texture node1.5.SIGNIFICANCE OF STUDYWhen we are connecting ambient occlusion texture to number of shader most of them are facing the problem l ike connecting with shader one by one some time we may miss some shader while connecting and also it will take time to connect to lot of shader Here am going to do this dissertation for solving these problems. Here I am going to simplify the ambient occlusion texture by MEL script1.6.HypothesisThe hypothesis of this project is to simplify the ambient occlusion texture using Maya embedded language (MEL)Chapter 2 Literature Review2.1.Literature Mastering Maya 2009 Eric Keller, Eric Allen and Anthony Honn 2009This book speaks about how ambient occlusion forms form indirect light rays and ambient occlusion effect can bring from Final Gathering and it will take more render time when u create in Final Gathering The above information help to get some knowledge and information about ambient occlusion.2.2.Literature Mental ray for Maya 3ds max and XSI Livny BoazAmbient occlusion adding realism and produce more details in the output and render will be fast when we compare to Final gathering a nd Globule illumination how ambient occlusion works and explain detail about ambient occlusion attribute and also tell about what are the different between occlusion and ambient occlusion2.3.Literature Introducing Maya 2011 Dariush DerakhshaniWe can take ambient occlusion as separate render pass that to help add more depth in models and later we can adjust in compositing. Ambient occlusion give great contact shadows2.4.Literature Maya Visual Effects the innovators guide Eric KellerAmbient occlusion is the easy and quick way to get Global illumination and tell how ambient occlusion note works in texture. Ambient occlusion produce soft shadows as like real world. when two models are placed near certain amount of light will be block and u will get soft shadows at the corner of the object2.5.Literature Rendering with Mental ray 3Ds Max Joep Van Der SteenThere are different types of shadow in 3ds max like normal 3ds max shadows and ray trace shadows .but normal shadows wont work in me ntal ray. If u need to get accurate shadows go for ray trace but render time will be increases when compare to normal shadows. Bounce light gives u realistically feel as like real life lighting. In real life light wont stop travel when its hits the ground it will hit and bounce for certain distance till its die and ambient occlusion also the one form of creating bounce light or indirect lighting for the scene but ambient occlusion wont be physically correct lighting when compare to FG(Final Gathering ) and GI (Globule illumination ). Ambient occlusion give reflective occlusion where we wont get in normal occlusion.2.6.Literature Writing Mental ray shader perceptual Introduction Andy KopraThis book tells about how ambient occlusion rays are calculating in the scene and tell about how Technically ambient occlusion works in MEL scrip this book gives me clear idea how to develop my scrip in MEL2.7.Literature Rendering Techniques 2006 Tomas Akenine-MllerAmbient occlusion shadow produce form ambient light. Ambient light emitsform all direction and produce soft shadows. Most of the production companiesusing ambient occlusion for lighting for time saving in lighting and rendering.2.8.Literature Maya secrets of the pros John L. Kundert-Gibbs, Dariush DerakhshaniAmbient occlusion techniques in production are used in two ways are backing of ambient occlusion texture and taking of ambient occlusion passes in render. In backing of ambient occlusion we cant tweak while compositing but In ambient occlusion render pass we can tweak and bring new effect in compositing.2.9.DVDDigital Tutors Mental Ray Nodes LibraryThis Tutor helps me what are the uses of the ambient occlusion how to connect ambient occlusion texture node in shader and explain clearly about the Attribute Editor of ambient occlusion to get good output.Chapter3 METHODOLOGYThis document consists of a quantitative and qualitative method by Survey and gathering information from Internet, Books, tutorials , articles , books, paper and videos.3.1.POPULATIONThe people who are suitable for this population is texturing artist, lighting artist, rendering artist.They were questioned regarding the ambient occlusion shader and its uses in production field. The population of this research work carries the production experienced person.3.2.SAMPLINGJudgment Sampling3.3.SCOPE AND LIMITATIONSThis research is limited to the ambient occlusion shader.Chapter 4 Lights in CG4.1 Overview4.2 Types of lightingChapter 5 Indirect lighting in CG5.1Introduction5.2 Final Gathering (FG) and Global illumination (GI)Chapter6 Ambient occlusion6.1 overview6.2 How it works6.3 Advantages of ambient occlusionChapter 7 Rendering7.1 Mental Ray rendering7.2 occlusion render over mental rayChapter 8 MEL8.1 Introduction to MEL8.2 Creating GUIChapter 4 Lights in CG4.1.IntroductionLightning in computer graphics (CG) is nothing but giving special effects to the scenes to improve the quality of animation. Lightings available for all kin d of occasions, all we need to do is just adjust the parameters. Most of them will not give more importance for lighting while creating there images or animations. Lighting plays very important role in computer graphics (CG), we can easily find the talented and untalented person in computer graphics (CG) by looking at the light effects given in the image or animation .Though we already know something about lightings in photography, film and video. We are just trying to bring the reality to computer graphics (CG). Lighting is used for creating a 3D effect by differentiating the foreground from background or else we can combine both to create 2D effect. This effect (Lighting) is mainly used to impress the viewer. Lighting is the most powerful tool in the computer graphics because this is the only tool which makes the viewer to feel. If your lighting perfectly fits for your image or animation then the final output will be much good to impress the viewer. Lighting can be expressed in tw o ways by being illuminated and a process of illumination. Lighting is defined globally by means of object which can be visible through the source illuminant application. Bouncing off lights or shiny objects can be made by the manipulation of light. If natural light is unavailable artificial lights can be used instead. Lighting is used everywhere and anywhere. Light is never said to be the same because of its variability, so lighting also changes. The natural sun light that we see in day to day life varies in a short period of time but the quality does not vary. The term state of lighting could in term mean intensity, its direction, its texture and form. This means something emotional. lighting is also a process of purposeful planning and design in which the light is to illuminate in an object. When lighting is necessary, the lighting position and placement are to be in considering, once deciding the intensity. Lighting process also refers in analyzing the light quality as it strike s the subject.4.1.ADDING LIGHT SOURCESAdding lights to the scenes can be done in several ways and also different kinds of lights available in lighting effects. Some kind of lights are used to highlight the background, foreground, character etc., we must choose the light which is highly suitable for the cases so that the people could not able to find which effect is used.There are several types of adding lights effects availablePOINT(OMMIDERECTIONAL)LIGHTSSPOTLIGHTSDIRECTIONAL LIGHTSAREA LIGHTSSite accessed on 27th sep Pixel Cinematography A Lighting Approach for Computer Graphics (SIGGRAPH 96 Course 30)SPHERICAL AREA LIGHTSFLAT AREA LIGHTSLINEAR LIGHTSMODELS SERVING AS LIGHTS4.2.1POINT(OMMIDERECTIONAL)LIGHTSPoint lights are also called as omni or omnidirectional lights, because it transmit in all directions, like any other lights e.g. bulb, sun etcThe main thing in giving this effect is checking the shadows it should not spread in all directions. In real life, u can see more unifor mly omnidirectional lights. Most of the times point lights are similar to real light bulbs for example, bulb lights spread allover the particular empty place, if a opaque thing (metal, wood etc.,) is kept in that place the shade will form behind that thing and side and size of the shade is depend on the location of the bulb.Though it is likely as omnidirectional we can spread it by using throw-pattern that is uneven. if you want to focus more light on some particular direction then you must do this action texture map to the light else by grouping the light with 3D object that produce shadowsThis light rays stimulated out from one infinitely small point in space, Its illumination and shadows passes out form the light in all direction.It is difficult to find a light which is uniformly omni directional in nature. Many light sources emit some amount of light in some directions. Uneven point lights can be used as a throw pattern, like a real bulb to emit more light in some direction rath er than in other direction. This is done by applying a texture to the light or else by grouping the light with the 3d object which will cast shadows.4.2.2.SPOTLIGHTSSpotlights is the major light effect which is commonly used in computer graphics (CG).This light effect is used by major computer graphics (CG) specialist because it can be used to focus on a specific target. Spotlight is also similar to point light sometimes but it slightly differs in pointing the target there are some limitations for spotlights are it should not exceed.we can determine the focus aim by rotating the spotlight. You can also fix a target for your focus so that the focus will always on that particular target.Spot Lights are the most used light in the lighting design of computer graphics. Most of the popular artist prefer spotlights to light a scene because, this light can be controlled in any times to aim light at a selected target. The emition of spotlight is light radiation from a point, same as like the point light. The illumination in the spotlight is controlled through a cone angle or a beam of the light. The rotation of the spotlight will determine where the beam is aimed. Objects can also be linked to light to stay in the same orientation position. A spotlight has more controls and options which is not found in other type of lights, some options like projecting a image map from the light, creating fog, etcWith the help of spotlight the falloff which is the softness of the cone, allows the intensity of light diminish more gradually in the edges of the beam.4.2.3.Directional LightsDirectional light is an infinity source of illumination from a distance. These lights are variously known as distant, direct or infinite light. This light sets a single vector for its entire illumination object from the same angle, doesnt matter the objects position. The shadows emitted by the directional light are in same direction and they are orthogonal projections of each 3d objects shape. The matt er in placing the directional light is which way its pointed. The directional light is not so easy in aiming to a preferred local area like point and spot light. A set of lights constituting from different angles can be used to produce fill light, even in the individual lights in all angles in a low intensity. These lights can fill very large areas with illumination appearing as ambient, like filling the daylight from the sky giving a quick effective global ambience. it deals with the light position where it is placed and it is all about the direction of the object, shadow and lit falls depend on the light location. However the sunlight is the major source of light we need some more light effects to impress the viewer most probably directional light is used. The directional light which needs some specific angle to present a proper lighting so that the person should concentrate more on angles.4.2.4.Area LightsThe lights like point and spot emits light from a infinity source into spac e, which is not simulating the size of physical light source in real life. Point light cannot be scaled in any dimension. To get more accurate simulations of the real light, this area light have definable scale, so the all the rays of light are not emitted exactly from the same point.If the light is scaled small, the illumination will appear similar to a point light. The larger scale of area light, make the light appear softer, shadows appears to soft and the illumination in nearby objects. The amount of shadows and light achieved with area light makes the scene excellent in realistic rendering.The source of the light comes from some long gap like windows etc, is said to be area lights. This effect is important when the image or animation dealing with the room setup for example if there is a room there might be some windows so we must implement the area lights. It matches the situation than any other lighting techniques4.2.5.SPHERICAL AREA LIGHTSSpherical area light is also like are a light it will spread in all directions. It is also called spherical light, spherical region of space is the source for the spherical light, this is mainly used in the case where the large light source. The spherical light has omni directional so the light does not have effect on our output. you can also replace the spherical light to point light when the illumination needs more concentration on light to cast soft edged shadows4.2.6.FLAT AREA LIGHTSArea light also available in flat shapes such as discs and rectangles. Light emitted from two dimensional areas can use less rendering time than three dimensional areas. The number of samples used to adjustable either approach. A rectangular area light is same as illuminated ceiling panel, a plane width and height that illuminates with naturally soft, diffused light. Light from ceiling is the major use of flat area light simulating the reflected illumination brightly lit walls and ceiling providing a soft. Aiming or rotating light change s your result, light from the edge of the flat area light is same as creating sharper shadow and also dimmer.4.2.7.LINEAR LIGHTSLinear light has same functionality as florescent tube and also scaled in one-dimension.it has a length soften the shadows and extend its illumination in one direction. How linear light affects the output. The shadow objects along the length of the light are very soft, but shadows from the end of the light are focused.We can use linear lights from fluorescent tubes, laser blasts. Line shape is not specifically needed, linear lights and it is used for general soft lighting scene they will not add as much as youre rendering time as other types. It is similar as spherical area light .4.2.8.MODELS SERVING AS LIGHTSLight effect by model serving as lights is a 3dimensional model in your scene sort of area light source. By using this model we can make a nontraditional shape of light like neon sign, it is also used as a true light sources, as shown in figure. Howev er, bright looking objects can be made by rendering the neon sign,and also by positioning other kind of light to the surface rounding area.Chapter 5 Indirect lighting in CG5.1IntroductionThe indirect illumination simulates caustics, global illumination and final gathering.the specification of light energy is required. To allow color the light energy is as a RGB triple. But the values of the RGB are usually much higher than the range for color. In the preprocessing step the number of photons stored from the light source is determined by STORE and the number of photons emitted is determined by EMIT. The photon emission stops when either of the limit is reached. Using the power law of 1/r(exp) energy from the light source decreases as the square of the distance increases from the source. The physical correctness is lost when the exponent is other than 2. During caustics preprocessing The number of caustics photon stored can be specified by the caustic photon value which controls it. Li kewise global photon value can be specified for global illumination. The value ranges from 10,000to 100,000.by increasing the value the accuracy increases and the bluriness decreases. In indirect lighting the lights sources are invisible by default. As the number of visible lights are increased the performance is reduces.5.2 Final Gathering (FG)The estimation of global illumination is done by a technique called Final gathering. It can be illuminated by either sampling a number of direction over the hemisphere or by averaging the total final gather points nearby. To improve the quality of global illumination final gathering is used. Without final gathering computation on a diffused surface is made by the photon intensity near that point. With final gathering the new rays of light is are made to hit the sample hemisphere for the determination of incident illumination. Using illumination from the globillium photon map and the illumination at the points of diffused surface is computed. Some rays hit a specular surface and their contribution for final gather color is zero. Tracing each ray utilizes lot of time so it is done when it is necessary. For purely diffuse scene final gathering eliminates low frequency noise and dark corners. As the final gather averages over many values of direct illumination fewer photons are needed. Final gathering can support only a single bounce. And multiple effect have far less impact on the image. The final gathering can perform these if the shaders can adjust the trace depth, otherwise it will be performed by photons by default. To control the photons coming from distant source of light final gathering is used and is good for film production. For CAD related applications photon mapping is used. Final gathering can be turned on or off in the options. In each final gathering the number of ray shot can be changed. The maximum distance at which the ray can be used depends on the scene extent. Decreasing the scene extent can reduce the noise but increase the render time.5.2.1.Global illuminationGlobal illumination simulates the light bouncing of an object. It has two steps process. the photon emitting light emits photon in to the scene. A photon map is created to store the intensity and place of the photon in three dimensional space. Then the surfaces are illuminated. It is based on the intensity of the photon. In global illumination diffusive value is a must. In the second part of the image the actual process is rendering of the image. The energy value is averaged and these values are interpolated to get the image as the light is bouncing of the diffused surface. After perfecting the in this method, the photon map can be saved and reused. Thus we can save the time of rendering each frame, provided the scene is static.This is the calculation of more complete light transfer model said to be global illumination. This accounts for the indirect reflected light transfer in the scene. There are two types of global illum ination, one simulates the behavior of the light of perfect specular light, and the second behaves in perfect diffuse light. These are most commonly referred to ideal specular, which hold ray tracing. Perfect diffuse reflections are called an ideal diffuse reflection, which is calculated using radiosity. This technique was developed in enhancing the realism in computer images in mimicking the light transfer. In periods it developed like image synthesis (photorealism) to simulation (photo accuracy). The radiosity is computed first and the ray tracer is computed to calculate the direct illumination the same way the reflection and refraction.5.2.3.Local IlluminationThis is the direct illumination from a light source, this means a method of lighting which come form the direct visible source. This will not take full light in account it only shows how the light affects the object that it calculates in the scene. Local illumination neglects the reflections and light propagations as its bou nced around the environment. The light transfer simulation in local illumination computes the light only produced from its light source itself to the object that it illuminates and stops there. In a sense an incomplete light transfers model because it computes only the effect of direct light and cheats by the environmental lighting settings as glow to make it as reflected.910 Local and Global5.2.4.Ambient LightThis is a light with constant intensity setting on the scene which serves as the sum of all in the direct illumination reflections in the scene. When describing this in effect ambient light is a kind of self-glowing illumination that mimics the object-to object light reflection. It is an independent intensity for all the objects in the scene. This light was invented to fake the direct illumination interobject reflection so the image will not be dark. This setting is adjusted globally through a scene parameter or per object.The preferable setting for ambient light in most scene s in set to be zero or low unless the object is producing light. This setting makes the fill light and the secondary lights influence in your scene more visible.Site accessed on 19th oct http//jmsoler.free.fr//tutor/lumiere_cornell_en.htmChapter 6 Ambient occlusion6.1.OverviewAmbient Occlusion is a lighting technique that which is used to cast shadows on objects. This is a technique used in lighting which is misunderstood as this method casts shadows on objects where light does not reach. Ambient occlusion creates or casts soft shadows around the object which gives out a molded look.In technical terms ambient occlusion is a global illumination method and is commonly referred to as a cheap trick for alternative method of global lighting method. This technique is to get ambient light in all contacted shadows. This is where ambient occlusion comes into being as some calculate the intensity of the light setup for every work file but most dont and the best way to overcome is to use ambie nt occlusion where this does all the calculation and gives a better quality render more than we can accept.6.2.How ambient occlusion worksAmbient occlusion is a technique which adds visual realism to the image without being physically correct. The ambient occlusion result can be used to darken concave areas, which human eye perceives as indirect illumination shadows, orcontact shadows. The advantage of ambient occlusion is its computational speed. As it may be computed with very short rays and as no additional shader evaluations are required, the performance may be significantly higher than forfinal gathering.6.3.Ambient occlusion gains render timeAmbient occlusion is enabled by default. However, no actual computations will happen until requested by further settings or by shaders. The ambient occlusion cache is setoffby default. In this mode, only shaders whichcall for ambient occlusionvalues will initiate computation on demand. If no such shaders exist in the scene, there is no ove rhead compared scenes rendered with ambient occlusion turned off. In case the ambient occlusion caching is enabled then mental ray will perform some computations before rendering starts, to fill the cache.The global defaults for ambient occlusion settings can be specified asscene optionsor on the mental raycommand line. Most of these values can be overwritten by a shader.Theambient occlusion cachingmay be enabled for the current rendering to gain overall speed. In this case, several preprocess passes will be computed. In the first pass, some ambient occlusion points are created on a coarse grid. Subsequent passes refine the grid adaptively. The density of the grid is determined by theambient occlusion cache densitysetting which gives theupper bound to the number of ambient occlusion points per pixel.Site accessed on 19th oct http//download.autodesk.com/us/maya/2009help/mr/manual/ao.html6.4.Results better than indirect lightAmbient occlusion is the easy and quick way to get Global il lumination and tell how ambient occlusion note works in texture. Ambient occlusion produce soft shadows as like real world. when two models are placed near certain amount of light will be block and u will get soft shadows at the corner of the objectAmbient occlusion adding realism and produce more details in the output and render will be fast when we compare to Final gathering and Globule illuminationAmbient occlusion refers to a type of shadowing that occurs when the ambient light in an environment is occluded (blocked) from reaching a surface by other nearby objects or other parts of the same object. You can see ambient occlusion effects in the photograph .The darkness that occurs in the cracks and crevices in the plaster design on an overcast day are a perfect example of ambient occlusion.Ambient occlusion effects are seen in many renders created using Final Gathering. that the ambient occlusion that occurs in a Final Gathering render lacks a certain amount of detail. Unless you increase the number of Final Gathering rays, detailed ambient occlusion shadows are difficult to achieve,and the more rays you emit into a scene, the longer the render time will be.This latter method is the most common approach and offers the most flexibility the occlusion pass can easily be modified in the compositing software. Eliminating the need to re-render the entire scene if a change needs to bemade. In this way you can use the ambient occlusion texture to augment the shadowing of a render pass that uses Final Gathering or as a substitute for rendering with Final GatheringLiterature Mental ray for Maya 3ds max and XSI Livny BoazLiterature Maya Visual Effects the innovators guide Eric KellerLiterature Mastering maya 2009- Eric KellerChapter 7 Rendering7.1 Mental Ray renderingMental ray rendering is capable of producing a realistic and quality image. It can render just with a single processor machine. It is achieved by advanced and proprietary acceleration technique. It achieve s better performance using parallelism on multi processor machine and also on network machines. Mental ray can be used on wide range of application, such as in full length movies, games, architectural design and on virtual models. Mental ray rendering is used as a standalone application for efficient rendering on local machines and as a software library on 3D content creation and CAD systems. Mental ray has a number of standard shaders which range from basic illumination to typical materials for architectural and design, car paint to physical sun and sky lighting. Mental ray has a built-in standard models for best rendering performance and quality cover.7.2.RenderingRay tracing is an option on mental ray. Ray tracing is used for rendering very complex lighting. Ray tracing software is based on ray tracing architecture which allows for the flexible implementation of lighting effect. It includes reflection, global illumination, refraction. To speed up the ray intersection calculation it uses advanced tree algorithms. From an on-demand loading of geometry it can adjust to dynamic scene manipulation. Ray trace is used to produce shadows of an object. Without the ray trace is turned on there will be no shadows. In ray tracing, the light path is tr