There are a few posts here about render to texture with Arnold being available in the latest update but I am struggling to get an AO map rendered. The scene is a house model, I used auto unwrap for the UV setup I use logarithmic exposure control so it is not view dependent Light is a Arnold skydome.
New In Gelato/Gelato Pro 2.2- Speed and memory improvements – scenes with huge displacement amounts now have can be rendered 5 times faster than before.
- Refined ray-traced reflection - the ability to handle multiple reflection rays with improved anti-aliasing.
- More accurate subsurface scattering techniques – by defining “albedo” and “Meanfreepath” coefficients.
- Enhanced texture converter – which lets you select, replicate and re-order individual color channels when creating textures.
- Mango now supports Maya Hair. - And includes a new shader for “Shave and a Haircut”, as well as, a new velvet shader.
- Windows XP Professional x64 support.
In addition to these changes, the Mango plug-in for Maya makes Gelato 2.2 easier to use and allows multiple versions of Maya to run simultaneously on your workstation. Other modifications include an updated User Interface, data exporting improvements, new pull-down menus and right-click functionality, standard placement of generated files in Mayaproject folders, better Maya batch rendering and other options via a custom Gelato XML file make workflow effortless and a more flexible SDB file system.
Gelato/Gelato Pro Selected Feature ComparisonFeatures | Gelato | Gelato Pro |
GPU acceleration | ||
Highest quality images | ||
Raytracing, incl. global illumination and ambient occlusion | ||
High-order geometry support | ||
Fully programmable shading | ||
Sorbetto interactive relighting | ||
DSO shadeops | ||
Multithreading | ||
Network parallel rendering | ||
Native 64-bit support | ||
Comprehensive support package |
See the full list
Image Quality
Unlimited Resolution: Gelato imposes no limit on the resolution of your final render; images can be as large as you like.
High-Quality Anti-Aliasing: Gelato has sub-pixel anti-aliasing, resulting in smooth surfaces. 'Jaggies' are nowhere to be seen.
True Displacement: Gelato shaders support true displacement, creating accurate representations of rough or uneven surfaces. Displacement occurs at frequencies as high as are visible in the image, not merely at object control vertices.
High-Quality Motion Blur: Gelato can realistically simulate movement through a still frame by blurring moving objects in 3D.
Depth of Field: Gelato can mimic the focus of a camera lens, creating the illusion of depth by blurring objects outside the focal range.
Automatic Adaptive Tessellation: Gelato tessellates the geometry on the fly, and does not require you send pre-tessellated polygons to the renderer. This creates smooth lines and curves without artifacts or aliasing, no matter how closely or from what angle you view the geometry.
Rich Geometry: Gelato supports a wide range of geometric primitives, not just polygons. These include:
- NURBS
- Bicubic/bilinear patches
- Subdivision surfaces
- Curves (hair)
- Wide curves (ribbons, feathers)
- Points (particles)
- Procedural geometry
Shading and Lighting
Sorbetto Interactive Shading and Lighting
With Gelato Pro you get fast relighting. Rapidly recompute changes to lighting.
With Gelato Pro you get fast relighting. Rapidly recompute changes to lighting.
- API-based: All Sorbetto functions exposed in the Gelato API and not dependent on any particular modeling or animation software.
- Relighting on final pixels: Including full antialiasing, motion blur, transparency, displacement, and production shaders. What you manipulate is always identical to the final rendered image.
- Fully adjustable lighting:
- Add/delete lights
- Move/reorient lights
- Change any light shader parameter
- Change light linking (what lights shine on what surfaces)
- Recomputes reflections automatically
- Selective relighting: Recompute lighting for a crop window or specified object for even faster results.
- Recompute dynamic shadows automatically
- Recomputes changes to camera parameters, including depth-of field, filters, and stereo parameters
- Interruptible: Make changes on the fly before the last render is finished.
- Plug-in support: Supported by the plug-in for Maya and soon by the plug-in for 3ds Max.
DSO Shadeops
Programmable Shading and Lighting: Gelato uses its own C-like shading language, to create surface textures and lighting for scenes using the renderer. The Gelato Shading Language (GSL) provides the flexibility required for the most complex scenes.
Layered Shaders: Instead of allowing only a single surface, displacement, volume, or light shader per object, Gelato allows you to assign multiple shaders of each type to an object. You may call several shaders in turn, specifying that one shader’s outputs be connected to the next shader’s inputs. This allows you to compose the operations of component shaders without modifying (or even having access to) the source code of any of the shaders involved, creating complex shaders without coding. For example, you can make any surface glossy by layering a 'gloss' shader atop any other shader, without needing the source code to either.
Antialiased Texture, Environment, and Shadow Mapping: Gelato can apply its high-quality anti-aliasing to the surface features and shadows of objects, not just to the geometry.
Volumetric Shadows: Provides realistic shadowing for fine and detailed geometry, like hair and fur, and for translucent objects.
Atmospheric Effects: Gelato realistically renders effects such as fog and smoke.
Caustics: Gelato can render caustics, patterns of light focused via reflective or refractive objects onto surfaces.
Subsurface Scattering: Gelato can use subsurface scattering, diffusing light beneath a surface and allowing it to re-emerge, realistically creating the translucent look of materials such as skin.
Average-Z ('Woo') Shadow Maps:
Cube-Faced Shadow Maps: Look up shadows from any direction with a single query.
Vertex Variables: Gelato allows the assignment of arbitrarily named and typed data to geometric vertices and will automatically interpolate the values across the surface and make the interpolated values available to shaders.
Unlimited Lights: Gelato does not impose an arbitrary limit on the number of lights in a scene.
Global Illumination: Gelato can mimic the subtle interactions of natural light sources by computing all the possible light interactions within a scene, tracing the light bouncing between objects and carrying their diffuse color properties with them. These colors are, in turn, transferred onto other neighboring objects. This results in much more accurate tones and shadows.
Ambient Occlusion: Gelato can be used to render an ambient occlusion pass of a scene, calculating the amount of ambient light that reaches any given point on a surface. This data can be used to recreate the contribution of ambient light in a scene.
Efficient Ray-Tracing: Gelato is capable of efficient ray tracing of large scenes, including raytraced shadows, reflections, indirect global illumination, and ambient occlusion visibility queries.
Sparse Spatial Databases: Gelato shaders can create their own such databases to store the results of arbitrary computations, save them to disk, or read existing databases to disk for quick interpolation.
Shader Library: Gelato comes with a library of basic shaders, suitable for the most common surfaces and lights.
PerformanceMulti-threaded: Gelato is multi-threaded on the CPU and, with PCI-Express, on the GPU. Thus it is able to harness all the computing power in a single node, resulting in maximum performance under a single license.
Native 64-Bit Support: Gelato Pro has a version that runs natively on Linux 64-bit systems, enabling you to address more memory space. Gelato Pro support for Windows 64-bit is on the way. (Gelato will run in 32-bit mode on both Linux and Windows 64-bit systems.)
Hardware Acceleration: Gelato is designed from the ground up to use the NVIDIA Quadro FX line of commodity programmable graphics hardware to speed up various internal functions. No special shaders, coding, or configuration is required to use the hardware and it does not affect flexibility or image quality in any way. It does, however, approximately double performance compared to CPU-only renderers. Subsequent releases of Gelato will take greater advantage of the graphics hardware and future graphics hardware will be even faster and more capable. For the past few years, graphics hardware has been doubling in speed every 6-12 months, whereas CPUs have been doubling in speed roughly every 18 months. So renderers based on graphics hardware will not only perform well now, but will rapidly outstrip the performance of CPU-only renderers over time.
Efficient Handling of Complex Scenes: Gelato is designed for the demands of film and efficiently allocates system resources and is stable while rendering the most complex scenes.
Efficient Memory Use: The components of complex scenes can exceed the memory capacity of even the most advanced systems. Gelato makes extremely efficient use of system memory, so that scenes are accurately rendered quickly.
Selective Ray Tracing: While ray tracing can produce extremely realistic lighting and shadow effects, it is computationally very intensive. Gelato uses scanline techniques where the use of ray tracing is not required, resulting in faster renders.
Fully Selective Lighting: Gelato offers maximum flexibility in lighting by allowing lights to apply to only particular objects if desired.
Production Readiness
Comprehensive Support: NVIDIA offers a comprehensive maintenance and support program for Gelato, ensuring that rendering problems will not critically delay your production schedule.
Network Parallel Rendering: Gelato Pro can use many machines on a network or server farm to render a single frame very quickly.
Holdout Matte Objects: Gelato supports holdout mattes, allowing objects to be composited in later in post-production.
No Eyesplits: Gelato’s algorithms never create eyesplits.
Low-Cost Sampling: Pixel sampling in Gelato is cheap in terms of system resources, so you can make the spatial and temporal quality of the pixel settings absurdly high with surprisingly low impact on the overall rendering time.
Multiple Cameras: Gelato allows you to place multiple cameras within a scene, just as you would lights or objects. And since Gelato organizes the scene in 'world space,' there is no need to treat the camera as the original origin and carefully placing the rest of world with the inverse transformation.
State Queries and Saved States: A program or plug-in making calls to Gelato may ask for the current value of a graphics attribute. There are also calls in Gelato’s API to save all or part of the current state, name it, and later restore all or part of that saved state. This makes it easy to transfer collections of attributes from one part of your scene hierarchy to another.
Geometry Sets: In Gelato, it is possible to name groups of primitives, allowing you to specify collections of primitives for ray tracing, for use as area lights, or for other uses.
Preview Mode: Permits ultra-fast rendering with low-quality shading for iterative renders used in scene construction and lighting before the final, high-quality render.
User-Priority Rendering: Select the area of the image you want to render first.
Stereo Rendering: (Gelato 2.0 Feature) Render stereo images faster than you could by rendering two images separately.
Interleave Utility: Combine alternate scanlines from two images for 'field rendering.'
Multiple Operating Systems: Gelato runs on Linux (RedHat, SUSE) and Windows XP.
Flexible Licensing: Gelato can make use of floating licenses over a network, permitting many machines to share a pool of licenses, reducing operating expenses. Or alternatively, Gelato can be dedicated to a specific machine.
Royalty-Free API: Gelato’s main Application Program Interface is a modern, C++-based API. To ease training requirements, the API is simple (few calls) and orthogonal (calls are non-overlapping). The API is available at no charge to encourage and foster the development of a wide range of tools for Gelato.
Plug-In I/O Architecture and Multiple Formats: Gelato does not require any specific input or output formats. Instead, it is designed to make use of plug-ins that allow Gelato to read any type of scene file or image input or output. Gelato ships with plug-ins for the most common I/O formats; others are available from third parties; and you can create your own using the API.
Multiple Scene Input Formats: Gelato does not prescribe a specific scene file format, forcing you to convert all data into that format. Instead, Gelato has a simple API for the creation of scene format plug-ins. When a file is input, the plug-in (DSO/DLL) for that format is dynamically loaded and told to read the scene file. Thus, you may store your scene in any format for which there is a plug-in and you may freely mix different files in different formats within a single scene. Available scene file plug-ins include:
- Python Binding: Gelato ships with a scene format plug-in that reads Python scripts that make calls to the Gelato API. This provides a flexible, fully scriptable method for scene input.
- RIB Scene File Reader: A plug-in that allows Gelato to read Renderman scene file formats is available for free.
Autodesk Maya Plug-In: Gelato ships with Mango, a plug-in to Autodesk’s Maya modeling and animation software package that reads scenes and objects created in Maya.
- Maya 8.5 support: Mango runs on the latest version of Maya.
- Sorbetto support: Mango with Gelato Pro supports all Sorbetto features.
- Familiar user interface: Mango uses the Maya GUI, familiar to any Maya user, minimizing training time.
- Loads Automatically: Mango loads whenever Maya is launched. No special startup commands are necessary. Once inside Maya, the user simply has to specify Gelato as the renderer.
- Geometry: Mango supports the a wide variety of geometry types.
- Mango supports Joe Alter’s Shave and A Haircut hair plug-in for Maya
- Surface Shaders:
- Hypershade translation: Mango automatically translates your Hypershade network to a series of Gelato shader layers.
- Gelato shaders: Mango can use any Gelato shader in your library, allowing you to assign it and set its parameters from within the Maya GUI.
- Lights and Shadows:
- Light shaders behave much like surface shaders
- Mango supports all Maya’s default light types
- Depth-mapped shadows
- Raytraced shadows
- Render Selected Objects: You can render selected objects in the scene or the entire Maya scene.
- Python Scripting: Attach Python scripts to Maya nodes using the Maya GUI for execution during rendering.
- Multiple Viewers: You can render to either Gelato’s image viewer or Maya’s render window.
3ds Max Plug-In: Gelato ships with Amaretto, a plug-in to Autodesk 3ds Max that reads scenes and objects created in Max.
- Geometry. Amaretto supports all 3ds Max geometry objects.
- Surface Shaders
- Supports Gelato shader networks
- Gelato GSO base material implementation in 3ds Max
- File parsing and automatic GUI generation of Gelato shaders in 3ds Max
- 3ds Max standard materials implemented as GSO shaders.
- 3ds Max maps implemented as GSO shaders
- Advanced shader preview in the material editor
- Lights and Shadows
- 3ds max direct lights
- 3ds Max default scene lights supported as direct lights.
- Omni lights support.
- 3ds Max spot lights
- Both raytraced shadows and shadow maps supported
- Global illumination support
- Ambient occlusion shader support
- Cameras.
- 3ds Max standard cameras and perspective viewports
- Orthogonal cameras and viewports
- Camera and object multi-segment motion blur with shutter angle support, centered, forward and backward alignment, segments and temporal quality controls
- Depth of field global or camera-specific settings, including explicit, target and custom focus objects support
- Output
- RGBA Output as TIFF, EXR, JPEG files
- Render Passes output to TIFF, EXR, JPEG for Diffuse, Specular, Ambient, Normals and any custom shader variables
Image Viewer: Gelato ships with a tool, called the Image Viewer or iv, for displaying multiple images in any format for which there is an installed plug-in. iv can correct the gamma of the display, zoom, and playback and loop sequences of frames.
Feature | Gelato 2.2 | Gelato Pro 2.2 |
Image Quality | ||
Unlimited Resolution | ||
High-Quality Antialiasing | ||
True Displacement | ||
High-Quality Motion Blur | ||
Depth of Field | ||
Automatic Adaptive Tessellation | ||
Rich Geometry | ||
Shading and Lighting | ||
Sorbetto Interactive Shading and Lighting | ||
DSO Shadeops | ||
Programmable Shading and Lighting | ||
Layered Shaders | ||
Antialiased Texture, Environment, and Shadow Maps | ||
Volumetric Shadows | ||
Dynamic Shadows Support | ||
Recompute Changes to Camera Parameters (DOF, Filters,and Stereo) | ||
Atmospheric Effects | ||
Caustics | ||
Subsurface Scattering | ||
Average-Z (“Woo”) Shadow Maps | ||
Cube-Faced Shadow Maps | ||
Vertex Variables | ||
Unlimited Lights | ||
Global Illumination | ||
Ambient Occlusion | ||
Fog Lights: Volumetric Support of Spotlights | ||
Efficient Raytracing | ||
Sparse Spatial Databases | ||
Shader Library | ||
Variable-length Shader Array Parameters | ||
Mesh Per-Face Attributes | ||
Performance | ||
Multithreaded | ||
Native 64-Bit Support | ||
Hardware Acceleration | ||
Efficient Handling of Complex Scenes | ||
Efficient Memory Use | ||
Selective Raytracing | ||
Fully Selective Lighting | ||
Production Readiness | ||
Comprehensive Support | ||
Network Parallel Rendering | ||
Holdout Matte Objects | ||
No Eyesplits | ||
Low-Cost Sampling | ||
Multiple Cameras | ||
Saved Queries and States | ||
Geometry Sets | ||
Preview Mode | ||
User-Priority Rendering | ||
Stereo Rendering: off-axis and Parellal | ||
Interleave Utility | ||
Multiple Operating Systems | ||
Flexible Licensing | N/A | |
Royalty-Free API | ||
Plug-In I/O Architecture and Multiple Formats | ||
Multiple Scene File Formats | ||
Python Binding | ||
RIB Scene File Reader | 3rd Party | 3rd Party |
Autodesk Maya Plug-In | ||
Autodesk 3ds Max Plug-In | ||
Shave and a Haircut Plug-in for Maya support | ||
Image Viewer |
The ambient occlusion map (middle image) for this scene darkens only the innermost angles of corners.
In computer graphics, ambient occlusion is a shading and rendering technique used to calculate how exposed each point in a scene is to ambient lighting. For example, the interior of a tube is typically more occluded (and hence darker) than the exposed outer surfaces, and the deeper you go inside the tube, the more occluded (and darker) the lighting becomes. Ambient occlusion can be seen as an accessibility value that is calculated for each surface point.[1] In scenes with open sky this is done by estimating the amount of visible sky for each point, while in indoor environments only objects within a certain radius are taken into account and the walls are assumed to be the origin of the ambient light. The result is a diffuse, non-directional shading effect that casts no clear shadows but that darkens enclosed and sheltered areas and can affect the rendered image's overall tone. It is often used as a post-processing effect.
Unlike local methods such as Phong shading, ambient occlusion is a global method, meaning that the illumination at each point is a function of other geometry in the scene. However, it is a very crude approximation to full global illumination. The appearance achieved by ambient occlusion alone is similar to the way an object might appear on an overcast day.
The first method that allowed simulating ambient occlusion in real time was developed by the research and development department of Crytek (CryEngine 2).[2] With the release of hardware capable of real time ray tracing by Nvidia in 2018, ray traced ambient occlusion (RTAO) became possible in games and other real time applications.[3] This feature was added to the Unreal Engine with version 4.22.[4]
- 1Implementation
Implementation[edit]
3D animation of ambient occlusion enabled on the animation to the right.
In the absence of hardware-assisted ray traced ambient occlusion, real-time applications such as computer games can use screen space ambient occlusion (SSAO) or horizon-based ambient occlusion (HBAO) as a faster approximation of true ambient occlusion, using pixel depth rather than scene geometry to form an ambient occlusion map.
Ambient occlusion is related to accessibility shading, which determines appearance based on how easy it is for a surface to be touched by various elements (e.g., dirt, light, etc.). It has been popularized in production animation due to its relative simplicity and efficiency.
The ambient occlusion shading model offers a better perception of the 3D shape of the displayed objects. This was shown in a paper where the authors report the results of perceptual experiments showing that depth discrimination under diffuse uniform sky lighting is superior to that predicted by a direct lighting model.[5]
The occlusion at a point on a surface with normal can be computed by integrating the visibility function over the hemisphere with respect to projected solid angle:
where is the visibility function at , defined to be zero if is occluded in the direction and one otherwise, and is the infinitesimal solid angle step of the integration variable . A variety of techniques are used to approximate this integral in practice: perhaps the most straightforward way is to use the Monte Carlo method by casting rays from the point and testing for intersection with other scene geometry (i.e., ray casting). Another approach (more suited to hardware acceleration) is to render the view from by rasterizing black geometry against a white background and taking the (cosine-weighted) average of rasterized fragments. 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.
In addition to the ambient occlusion value, a 'bent normal' vector is often generated, which points in the average direction of unoccluded samples. The bent normal can be used to look up incident radiance from an environment map to approximate image-based lighting. However, there are some situations in which the direction of the bent normal is a misrepresentation of the dominant direction of illumination, e.g.,
In this example the bent normal Nb has an unfortunate direction, since it is pointing at an occluded surface.
In this example, light may reach the point p only from the left or right sides, but the bent normal points to the average of those two sources, which is, unfortunately, directly toward the obstruction.
Variants[edit]
- SSAO
- Screen space ambient occlusion
- SSDO
- Screen space directional occlusion
- RTAO
- Ray Traced Ambient Occlusion
- HDAO
- High Definition Ambient Occlusion
- HBAO+
- Horizon Based Ambient Occlusion+
- AAO
- Alchemy Ambient Occlusion
- ABAO
- Angle Based Ambient Occlusion
- PBAO
- Pre Baked Ambient Occlusion
- VXAO
- Voxel Accelerated Ambient Occlusion
- GTAO
- Ground Truth based Ambient Occlusion[6]
Recognition[edit]
In 2010, Hayden Landis, Ken McGaugh and Hilmar Koch were awarded a Scientific and Technical Academy Award for their work on ambient occlusion rendering.[7]
See also[edit]
References[edit]
- ^Miller, Gavin (1994). 'Efficient algorithms for local and global accessibility shading'. Proceedings of the 21st annual conference on Computer graphics and interactive techniques. pp. 319–326.
- ^'AMBIENT OCCLUSION: AN EXTENSIVE GUIDE ON ITS ALGORITHMS AND USE IN VR'. ARVIlab. Retrieved 2018-11-26.
- ^Ray Traced Ambient Occlusion. Nvidia.
- ^'Unreal Engine Adds Support for DX12 Raytracing'. ExtremeTech.
- ^Langer, M.S.; H. H. Buelthoff (2000). 'Depth discrimination from shading under diffuse lighting'. Perception. 29 (6): 649–660. CiteSeerX10.1.1.69.6103. doi:10.1068/p3060. PMID11040949.
- ^'Practical Realtime Strategies for Accurate Indirect Occlusion'(PDF).
- ^Oscar 2010: Scientific and Technical Awards, Alt Film Guide, Jan 7, 2010
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