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| | Ambient occlusion - Wikipedia, the free encyclopedia |
 | | Ambient occlusion is a shading method used in 3D computer graphics which can help add realism by taking into account attenuation of light caused by obstructive geometry. | | | However, ambient occlusion has mostly been popularised by its recent use as an efficient production technique by computer animation studios and global illumination renderers such as RenderMan. | | | This approach is an example of a "gathering" or "inside-out" approach, whereas other algorithms (such as depth-map ambient occlusion) employ "scattering" or "outside-in" techniques. |
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http://en.wikipedia.org/wiki/Ambient_occlusion
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| | Ambient Occlusion, Image-Based Illumination, and Global Illumination |
| | The occlusion function computes the average unoccluded direction while it is computing the occlusion, and also interpolates the unoccluded directions. | | | Ambient occlusion is computed on the white ground plane, and 'useopacity' is set to 1 in the occlusion call. | | | As already mentioned, when the irradiance is computed, the ambient occlusion is computed as well, since the additional information is for free. |
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http://www.et.byu.edu/groups/anim_prman/docs-6.0/prman_technical_rendering/AppNotes/globillum.html
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| | Ambient Occlusion |
| | There are two basic approaches for computing ambient occlusion. | | | Since this requires computing occlusion at every triangle, this approach is in general O(N^2), although with efficiency structures (such as bounding volume hierarchies) it can be reduced to O(NlogN). | | | A better way to implement this is use two (or more) batches of occlusion queries, and ping-pong between them. |
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http://www.cs.unc.edu/~coombe/research/ao
(555 words)
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| | Depth Map based Ambient Occlusion |
| | Once the ambient occlusion pass has been rendered, the indirect lighting contribution to the scene is then calculated by applying an environment map of the scene into which the object is to be integrated. | | | If you are studying ambient occlusion then this tutorial might still have some value by way of instruction on the reasoning and methodology of ambient occlusion but beyond that I think its time has past. | | | This is important as it affects the way the values that these images parse to the final environment light render. |
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http://www.andrew-whitehurst.net/amb_occlude.html
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| | oZone3D.Net Tutorials - Ambient Occlusion Lighting using GLSL |
| | The calculation of the occlusion data is rather simple: starting from the center of a polygon, rays are projected in all directions in the higher hemisphere of the polygon. | | | The algorithm in pseudo-code for the ambient occlusion calculation is given in this topic in the oZone3D.Net benchmarking forum. | | | The occlusion data are stored at the level of each vertex as a vertex attribute. |
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http://www.ozone3d.net/tutorials/ambient_occlusion.php
(1669 words)
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| | Reflection Occlusion |
| | The environment pass has been multiplied with the reflection occlusion pass, the result is then added to an ambient occlusion pass. | | | This problem can be solved with a combination of environment maps and reflection occlusion. | | | Min/Max defines the minimum and maximum rays that are used to calculate the occlusion. |
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http://www.illuminatelabs.com/tutorials/refoccl/refoccl.html
(640 words)
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| | Mental Ray Ambient / Reflection Occlusion Shader Tutorial |
| | One of the features of the ambient occlusion map is that you can use a bitmap to define what colour should be used for each ray sample. | | | This will generally lead to a slight reduction in overall occlusion proportionate to the distance specified, but it will yield faster render times as each ray does not have to be traced so far. | | | Of course we all know that reflection maps are MUCH faster than raytraced reflections, but their downfall is that they do not reflect near by objects realistically or indeed change their reflection when those objects move. |
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http://www.cg-academy.net/pages/free_tutorials/tut_ambient_occlusion_shader/tut_mentalray_ambientocclusion_shader.htm
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| | Illuminate Labs Occlusion Tutorial |
| | Set the Output to Environment + Occlusion and the Environment Color to [RBG: 74,120,158] on the Occlusion shader. | | | The normal data is stored in the RGB channels and the occlusion values is stored in the alpha channel. | | | The calculation of occlusion values are performed by a Turtle shader called ilrOccSampler. |
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http://www.illuminatelabs.com/tutorials/ambientoccl/ambientoccl.html
(966 words)
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| | : ShadeVis |
| | The most common techniques to compute ambient occlusion is based on shooting rays from each surface element to evaluate the quantity of light that reach it. | | | We used and described this technique for computing the ambient occlusion term in the following paper. | | | We have used this approach (and a slightly modified version of this code) to computing occlusion or visibility information also for estimating the best direction where shooting rays when recovering the detail (normal maps) of a High-res mesh over a Lowres mesh. |
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http://vcg.sourceforge.net/tiki-index.php?page=ShadeVis
(510 words)
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| | [No title] |
| | We use methods similar to Radiosity Form-Factor evaluations to compute the occlusion values and bent-normals. | | | Our project goal was to create a real-time environment renderer using precomputed ambient occlusion values. | | | The occulsion value for a vertex is the normalized sum of all rays that make it out to the environment. |
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http://www.cs.wisc.edu/~ltokheim/ambenv
(511 words)
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| | Untitled Document |
| | The occlusion information is computed by shooting rays at R-the direction of reflection. | | | This problem can still be solved by the ambient occlusion approach. | | | Reflection occlusion can produce some complexity of a full ray-traced render, partly at least, but without the expense of the latter. |
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http://zj.deathfall.com/reflocc.htm
(267 words)
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| | XSI Base Forum - Ambient Occlusion |
| | I was constructing the ambient occlusion shader in the render tree, but I couldn't find the Divide node. | | | I think occlusion pass as a kind of alpha channel that controls ambient light and/or environment reflection in the same way. | | | Your shader is ray traced reflection dipendent and works well with stills but with animation problems may occur; you can bake the occlusion pass as a texture but it's not a precise solution... |
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http://www.xsibase.com/forum/index.php?board=6;action=display;threadid=992
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| | Gamasutra - Features - "Hardware Accelerating Art Production" Printer Friendly |
| | An overview of ambient occlusion follows, leading to a three-step workout, turning an initially sluggish hardware approach into a lean, streamlined solution. | | | So our occlusion term is now a vector, computed in much the same way as with AO, except for the presence of basis functions B | | | I'll also show how these can be extended to handle higher-order occlusion (precomputed radiance transfer) before closing with a round up of other accelerated preprocesses that you might wish to consider. |
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http://www.gamasutra.com/features/20040319/hill_pfv.htm
(5355 words)
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| | resources/practical_ambient_occlusion_1 |
| | The passes were combined in Photoshop by multiplying the ambient occlusion pass with the basic plastic shaded render and adding the specular pass on top to achieve a convincing result typical of a studio shoot. | | | He decided to stay within the computer theme and to produce images which could be part of a campaign and which illustrates the merits of the DVD as a storage medium over both DAT tapes and floppy disks. | | | Since Peter was using a fairly low resolution polygonal model of a keyboard and he wanted to emphasis a particular key he used a shallow depth of field. |
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http://www.techimage.co.uk/resources/practical_ambient_occlusion_1.html
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| | CGTalk - Occlusion and Ambient Occlusion |
| | There are also Ambient Occlusion scripts like RayDiffuse for the Maya Software renderer, but I'm a Mental Ray-aholic so I recommend the Dirtmap shader approach. | | | The 'Ambient' part looks at your scene environment (colour, texture or HDRI image for example) and applies some ambient shading to your object based on what it finds. | | | This is essentially the direction that "most of the light" comes from the environment to reach the surface, and it corrects subtle problems like the surface taking colour from a part of the environment that is blocked to it, |
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http://forums.cgsociety.org/showthread.php?t=171191
(1286 words)
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| | [No title] |
| | You can still use the shader for characters, but the ambient occlusion map won't be quite as realistic Also, the global illumination map is only valid for the one spot in the environment where it was created. | | | We can't really do that in real-time, so the ambient occlusion map only works for rigid objects that don't deform. | | | If you apply the shader to a moving character, you need to create a new cube map for each area of your world and come up with a method for telling the shader which cube map to use based on proximity. |
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http://www.monitorstudios.com/bcloward/HLSLglobalIllum.fx
(677 words)
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| | Ambient Occlusion |
| | The concept of ambient light has been with computer graphics since virtually the beginning, but has largely fallen into disuse. | | | For true accuracy, you can average the rays that don't hit anything, and access the environment map with that instead of the reflection vector. | | | I used Photoshop to combine the three layers. |
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http://www-viz.tamu.edu/students/bmoyer/617/ambocc
(845 words)
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| | elYsiun.com :: View topic - Tutorial: non-raytraced ambient occlusion |
| | We are going to approach the ambient occlusion as a separate rendering pass that will need to be composited later with the other passes (for example using the Sequence Editor), so have in mind that a little additional work will be needed if you want to incorporate the AO in a single pass rendering. | | | One thisng you should also do is add a hemilight, set with no shadows and a slight blue colour to it. | | | While most AO algorithms use raytracing, there is a way to fake AO very successfuly using only conventional shadow-mapping. |
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http://www.elysiun.com/forum/viewtopic.php?t=18247
(1593 words)
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| | in.out.side: the shell - Technology and workflow |
| | In the end, for each distinct object in the scene we have a special "ambient occlusion" texture that we use at rendering time in the lighting calculations. | | | We wrote a tool to do that (screenshot on the right), and the results turned out to be very good - given an example texture, we only need to set several parameters and the tool generates the texture for any model in several seconds. | | | The high-polygon version (56000 triangles) is not used for realtime rendering at all, just for normal map computation. |
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http://www.nesnausk.org/inoutside/Technology.php
(1585 words)
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| | Depth-based Ambient Occlusion |
| | The most time-consuming shadow buffering is viewpoint-independent, which is the most advantage that depth map based ambient occlusion has over a ray-traced solution. | | | The basic idea of depth map based solution is to make a dump of the shape of geometry with a number of depth(shadow) maps shot from different viewpoints(spotLights). | | | Depth map based solution cantains three stages of render, and each of they requires using special shaders and a lot of tricks. |
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http://zj.deathfall.com/depthbasedOcc.htm
(1004 words)
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| | CG Education |
| | Also note, renderers that include a "skylight" but not an "ambient occlusion shader" generally do not include a maximum distance value in their ambient occlusion calculation, which specifies a cutoff value for how far to shoot the ray before declaring it's a non occluded ray. | | | Note: the actual math behind implementing this technique is far more complex, and each renderer does it a slightly different way, but this should give you the basic idea. | | | But since a skylight is supposed to be a simulation of a sky, and not a more general purpose ambient occlusion shader, many do not include this feature. |
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http://neilblevins.com/cg_education/ambient_occlusion/ambient_occlusion.htm
(692 words)
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| | :: Tutorial :: |
| | The idea behind this workflow, is to come up with way of having rendered image that combines both Ambient Occlusion and color diffusion without having to use external composting package. | | | The correct way of doing it in composting package would be using a “multiplier node” | | | The result render would be something ike this. |
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http://www.pixelcg.com/tutorials/AO.html
(165 words)
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| | Cinema 4D R9.5 XL Competitive Upgrade - Authorized Reseller - Safe Harbor 800-544-6599 |
| | With the newly integrated Ambient Occlusion, Advanced Render now uses the environment to simulate shadow casting. | | | The shadows are calculated based on environment shadows and can be done either for individual objects or for the entire scene. | | | The normal mapping technology (used in particular by game developers) even lets Normal maps be created from objects with applied SubPolyDisplacement. |
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http://www.sharbor.com/products/MXNN0300012.html
(5308 words)
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| | Jedi Council Forums - Ambient Occlusion Tutorial for 3ds max. |
| | I just wanted to say that I´d like to try out the program because the AO technique is so much easier than in other programs I´ve used so far (Blender and EI). | | | But I´m sure this can be applied to other programs as well. | | | FYI, MAX isn't the only program that can do this. |
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http://boards.theforce.net/message.asp?topic=16785820
(406 words)
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| | 3DELIGHT User's Manual: 6.4 Global Illumination |
| | Ambient occlusion (also known as "geometric exposure") is trivially computed using the | | | to compute occlusion can be much more costly than using | | | shadeop to determine the un-occluded direction (see occlusion shadeop). |
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http://www.3delight.com/ZDoc/3delight_39.html
(1341 words)
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| | Everflow Tutorials: Max 7: Ambient Occlusion |
| | The closer the occlusion, the stronger the representation. | | | Similar to the level of a Gaussian Blur filter in Photoshop. | | | This occlusion is also known as the 'dirtpass' or 'dirtmap'. |
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http://everflow.com/support/tutorials/AO/Everflow_AmbientOcclusion1.html
(543 words)
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| | Untitled Document |
| | This multiplies the diffuse by the ambient environment. | | | Using the ‘Dirtmap’ shader I unchecked Probe geometry and checked the Use Environment setting. | | | A pass containing only the texture/diffuse colour mapped on our object. |
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http://www.tahlniran.com/tutorials/shake/ambOcc/ambOcc_tute.htm
(1468 words)
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| | "TRIX R 4 KIDS" Vol. 2 |
| | As directions are probed for occlusion, the current environment is also sampled and weighted based on how occluded that particular direction is. In this mode the output of the function is the gathered weighted environment colors multiplied by the bright color, and as a convenience the dark color (if non-black) is simply added to this. | | | The average unoccluded world space normal direction is calculated and returned encoded as a color where red is x, green is y and blue is z. | | | The setup is fairly simple, a copter model is the only geometry we have in the scene, there is also an IBL node for environment reflection and environment sampling. |
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http://www.jupiter-jazz.com/wordpress/wp-content/data/tr4kv2/html/chapter2-SSS.html
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| | 3dm3.com - FREE 3DS MAX MODELS FREE 3DS MAX TUTORIALS MODELING CAR BLUEPRINTS 3D GALLERY 3D GIRLS CG MOVIES DOWNLOADS |
| | The Ambient Occlusion method is basically rendering out an occlusion pass(which is a grayscale or a tinted image based on environment map) and then overlaying this image over a flat lit diffuse pass(achieved by ambient lighting, I'll describe it later) to represent the shadowing caused by the environment. | | | In the Siggraph 2002 presentation “Production-Ready Global Illumination”, ILM Technical Director Hayden Landis tells about this alternate method they developed for simulating GI effectively with speed. | | | With the introduction and integration of mental ray, 3dsmax has gained a strength in its rendering department, particulary the photo-realistic section. |
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http://www.3dm3.com/tutorials/occlusion
(416 words)
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| | NVIDIA Forums -> Gelato and ambient occlusion performance |
| | If this is an input file you would be willing to share with us, please send it our way and we can use it specifically as an optimization target. | | | I'm using a RIB file for input, with the Ribelato input translator. | | | I've been doing a set of ambient occlusion quality/rendertime tests with Gelato over the past couple of days; you can see the settings and the results at http://www.cinital.com/content/category/5/68/44/. |
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http://forums.nvidia.com/index.php?showtopic=1061
(482 words)
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| | Ambient Occlusion Fields |
| | We present a novel real-time technique for computing inter-object ambient occlusion. | | | This volumetric information is then used at run-time in a fragment program for quickly determining the shadow cast on the receiving objects. | | | For each occluding object, we precompute a field in the surrounding space that encodes an approximation of the occlusion caused by the object. |
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http://www.tml.tkk.fi/~janne/aofields
(96 words)
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| | Devon Strawn : Ambient Occlusion Shading |
| | An example with roll-overs to illustrate ambient occlusion & directional lighting. | | | Render Contact Shadows: useful for "placing" an object in its environment. | | | Reflection Occlusion: using occlusion map to attenuate environment map - fixes visual artifact of self-occluded areas affected by environment map. |
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http://www.secretrobot.com/Apps/AmbientOcclusionShading.html
(769 words)
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| | Amazon.com: efrontier Poser 6: Software |
| | The new Ambient Occlusion shader node makes figures and objects appear as though they are in a natural lighting environment. | | | You can render out your 3D scene display with the OpenGL Preview renderer, and easily switch between SreeD Software and OpenGL Hardware for scene previews--which means you can maximize your system’s resources and spend your time creating rather than waiting. | | | Ambient Occlusion makes figures seem as though they are in the natural lighting environment of the real world. |
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http://www.amazon.com/exec/obidos/ASIN/B00083SCCM/categorywebco-20?dev-t=D2A7ZI28T8B3P9&camp=2025&link_code=xm2
(3941 words)
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| | GameDev.Net Discussion Forums - User Profile |
| | Use your video card GPU to compute ambient occlusion really fast. | | | Regrettably, but we're unable to reproduce this error. | | | I tried syncronizing the system's clock with time.org, but that didn't work. |
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http://www.gamedev.net/community/forums/profile.asp?mode=display&id=69967
(352 words)
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| | Meeting Summaries |
| | In that case, the mib_amb_occlusion shader could be attached directly to the SG/material, instead of the usual location as an ambient input to a normal illumination shader. | | | The one thing we did notice is that lightmaps do not distribute well if you deselect rendering on the master machine. | | | On March 29, at Digital Dimension, we focused on Final Gathering and Ambient Occlusion in mental ray 3.4. |
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http://www.lamrug.org/summaries.html
(1232 words)
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| | ambientocclusion |
| | So anything that is 100% exposed to the environment, will render 100%. | | | This also is neccessary for the ambient occlusion to work... | | | Also, make sure that the skylight multiplier to 1.0. |
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http://www.geocities.com/night_sky_vfx/ambientocclusion.html
(296 words)
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| | lightEngine3d |
| | Ambient lighting is calculated using an environment map, allowing for quick, | | | occlusion lighting into non-raytracing renderers or real-time systems. | | | : Ambient occlusion data may be rendered or baked out as image maps |
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http://www.lightengine3d.com/downloads/plugins/rayDiffuse/rd_desc.html
(282 words)
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| | RENDERMAN - AMBIENT OCCLUSION |
| | The value hilited in red is the value that controls occlusion quality. | | | Ambient occlusion has more in common with techniques used by illustrators than photo-realists. | | | In the code for their first sample occlusion surface shader they refer to a function called shadingnormal(). |
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http://www.fundza.com/rman_shaders/ray/ambient_occlusion/occlude1.html
(1015 words)
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| | Untitled Document |
| | While this method produces fairly realistic results, I wanted to see what kind of interesting affects could be created by adjusting the ambient occlusion parameters and logic statements. | | | Possibly, a lighting model for non-photorealistic rendering (NPR) could be created. | | | Using ambient occlusion is an easy way to approximate global illumination without the cost of radiosity calculations. |
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http://studentpages.scad.edu/~mparro21/globalIllumination.html
(183 words)
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| | GDC 2005 Presentations |
| | How to compute ambient occlusion efficiently using the GPU, and how to apply it to indirect lighting computations. | | | A collection of useful techniques, including particle systems, cloth simulation, antialising, ambient occlusion, and more. | | | Case studies of interesting ways to use the GPU's power to achieve a variety of high-quality effects. |
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http://developer.nvidia.com/object/gdc_2005_presentations.html
(389 words)
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| | SketchUp User Forum |
| | I noted that the program uses "ambient occlusion" to create realistic shadows. | | | "Ambient Occlusion is the technique developed at, and used within, some of the best known studios in the world. | | | Perhaps there is something in the technique that could be adapted to SketchUp without a performance hit. |
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http://www.sketchup.com/forum/read.php?f=4&i=1515&t=1515
(759 words)
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| | Ambient Occlusion Plugin for Cinema 4D |
| | It is my debut at writing a plugin for Cinema 4D, so it may be buggy, inefficient or contain stupid beginner's mistakes. | | | This is a plugin for Maxon Cinema 4D that implements the ambient occlusion algorithm. | | | Standart usage for ambient occlusion is as shader for envrionment lighting, usually at a level between 5% and 25%. |
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http://www.keindesign.de/stefan/cinema/ao.html
(277 words)
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| | Circlesoft R&D :: Hardware-Based Ambient Occlusion |
| | I present a new hardware-based method that utilizes occlusion queries to determine the percentage of the environment that is visible at each face. | | | Ambient Occlusion is a technique that approximates how a mesh occludes itself from incoming ambient light. | | | However, Matt Pharr and Simon Green of Nvidia have published a method that uses hardware-based shadow maps to generate the accessibility values. |
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http://www.circlesoft.org/pages.php?pg=ao
(222 words)
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| | Multipass Rendering - Part 2 |
| | It may add ambient light where it is wanted, but it will also add it where it is NOT wanted, making the image lack contrast. | | | For more in depth information about Ambient Occlusion, you can try these websites: | | | You may even group all objects in the scene to a single parent axis, making it even simpler to manage all objects in a scene. |
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http://www.elink.net.au/~lahl/tutorials/Multipass/Multipass-2.htm
(1379 words)
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| | Forza Motorsport - PGR3: Bizarre Creations Studio Update 02 |
| | Essentially this gives us a minimum and a maximum light level (minimum being the ambient, maximum being the ambient plus the diffuse). | | | So, as a summary, the game works out the lighting on the car (on a per-pixel basis) based on the surrounding environment. | | | This ambient occlusion value can be calculated in our lighting tool and stored per-vertex on the models. |
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http://www.forzacentral.com/forum/showthread.php?t=4308
(1074 words)
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| | cgkit tutorial: Baking texture maps |
| | In the above example, we were using a simple shader that just outputs the ambient occlusion contribution. | | | Such maps can then be used to rerender the scene much more quickly or the map can be used for interactive rendering in games or VR applications. | | | Often, this ambient part is just set to some constant color which makes the result appear rather flat. |
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http://cgkit.sourceforge.net/tutorials/baking/baking.html
(1950 words)
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| | Jon Reisch Home |
| | The Knight image above features ambient occlusion, environment map lighting, raytrace reflection, raytrace soft shadows, and depth of field. | | | This is an example of the visual richness ambient occlusion can help add! | | | No distribution, copying, or file sharing of this plug-in is permitted without expressed consent from the author. |
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http://www-viz.tamu.edu/students/jreisch/jrOcc_gallery.htm
(132 words)
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| | Everflow Tutorials: Max 7: Ambient Occlusion |
| | Above: an example of the Ambient Occlusion/Displacement with and without the 'weight' map. | | | Absolute black results in no Occlusion rendered on those polygons. | | | Apply our material to the object in question. |
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http://everflow.com/support/tutorials/AO/Everflow_AmbientOcclusion3.html
(285 words)
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| | Ambient Occlusion - NewTek Discussions |
| | I noticed that its also in the latest version of Pixels 3D. | | | Occlusion is a way of capturing 'shadow zones' that are greyscale images of your scene that can be used to control ambient or diffuse channels etc. You can get quite photo-real results using it without having to use radiosity. | | | I've just been playing with a free Ambient Occlusion shader for Electric Image and i'ts pretty cool. |
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http://www.newtek.com/forums/showthread.php?t=777
(247 words)
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