Research on sampling methods for real-time volume rendering.
Teaser video here.
Shadertoy volume rendering demo: Mt3GWs
Shadertoy sampling diagram: ll3GWs
Contacts: Huw Bowles (@hdb1), Daniel Zimmermann (daniel dot zimmermann at studiogobo dot com), Beibei Wang (bebei dot wang at gmail dot com)
Retweet to support this work: https://twitter.com/hdb1/status/769615284672028672
Volume rendering in real-time applications is expensive, and sample counts are typically low. When the camera is inside the volume, the volume samples typically move around with the camera which can cause severe aliasing. This repository provides a new, fast, efficient and simple algorithm for eliminating aliasing for this camera-in-volume case.
This repos started as the source code for the course titled A Novel Sampling Algorithm for Fast and Stable Real-Time Volume Rendering, in the Advances in Real-Time Rendering in Games course at SIGGRAPH 2015 [1]. The full presentation PPT is available for download from the course page here. While this is useful reading, the latest implementation takes a new approach which completely replaces most of the approaches introduced in the talk.
The latest approach, Structured Sampling, works by placing samples on a set of world-space planes, constraining their motion and eliminating noticeable aliasing. Right now we are in the process of working out the details, extending the method to 3D (as opposed to flatland 2D), and writing up an article.
Shadertoy volume rendering demo: Mt3GWs
Shadertoy sampling diagram: ll3GWs
This is implemented as a Unity 5 project (last run on 5.3.5) and should "just work" without requiring any set up steps.
The main scene is CloudsStructured.unity. The cloud render should already work in the editor. Press play and the Animator component on the camera will play our test animation if it is enabled.
There is also a ShaderToy running here: https://www.shadertoy.com/view/Mt3GWs
Article coming soon.
In the meantime there is a diagram shader here: https://www.shadertoy.com/view/ll3GWs
Uncomment the DIAGRAM_OVERLAY define in CloudsStructured.shader to see the diagram overlaid onto the render.
You may run into the following:
- If you see just the standard sky box render in the camera view, re-enable the CloudsStructured script on the camera. if it auto disables itself when you enable it, it is likely because the shader is not building. look in the console log for shader build errors. if you don't see any you may have already cleared them - perhaps try touching the shader file or reopening Unity.
- The current sample slices are all set up for flatland 2D. We're working on extending this to full 3D.
- The adaptive sampling method published here should be compatible with the new approach and will be reinstated.
- Code optimisation: much of the logic and computation in SetupSampling() can hopefully be extracted out to either the CPU (position dependent stuff) or a VS (direction dependent stuff). doc/OptimisationThoughts.txt has some more thoughts.
[1] Bowles H. and Zimmermann D., A Novel Sampling Algorithm for Fast and Stable Real-Time Volume Rendering, Advances in Real-Time Rendering in Games course, SIGGRAPH 2015. Course page.