Rendering Imrod

I was compelled to try and render the Imrod model that Jon Olick (worked for ID Software at one point) rendered with voxels. Below is a video of Jon's render, and below that is mine. Jon's is better...

800x600 ~60 fps - SVODepth(10) ~ 2 Million visible voxels

1x GTX 680

I have been optimizing all that I can without the ability to even debug my parallel code, as the Nvidia Cuda Development site has been down from a malicious attack for the past week. I have been in dire need of the Nvidia Parallel Nsight 2.2 debugging app.

I plan to implement voxel contours so that the voxels no longer have the cubical shape when viewed up close, but rather have a smoother surface that better represents the high poly source model.

Disclaimer: This model is the intellectual property of Dmitry Parkin - http://www.parkparkin.com/

Optimization Underway

I have been slaving away at this thing for a while now in an effort to optimize the heck out of it. I am making some progress.

640x480 - ~50 fps - SVO Depth(9)

1x GTX 580

OBJ polygon count: 6,615,041

SVO voxel count: 1,484,810 (22% the detail of OBJ)

OBJ file size: ~500 MB

SVO file size: ~88 MB (17% the size of OBJ) 

5% relative size difference over OBJ

My goal is to get the SVO files compressed down much further. Due to the hierarchical nature of sparse voxel octrees, much of the data I am currently saving to the file can actually be rebuilt at load time. I believe I can cut out at least 16 MB of data from the above example.

Octree Depth Visualization and Dynamic LOD

Here is something to help you wrap your head around how a Sparse Voxel Octree (SVO) is organized.

I rendered the model with each empty octant somewhat visible as a transparent shade of gray. As each primary raycast traverses into a deeper subdivision level within the octree, the rendered pixel gets brighter. If the ray intersects a terminal voxel (visible part of model), it returns the color to draw that pixel. I also show what reducing the maximum subdivision level rendered looks like (Inherent LOD).

First Real Voxel Model

This will probably be the first post anyone will see, as I don't think anyone would be impressed by the first two. This one has a little bit more eye candy. Not as boring as looking at meaningless cubes...

600x480 - ~60 fps - SVO Depth (7)

1x GTX 580

I wrote a Wavefront .obj file converter for getting polygonal models into a voxel format. All the converter does right now is it places a single leaf node (visible voxel) in the center of each quad polygon. The .obj file was exported from ZBrush with no UV map or textures; only polypaint was used to color it. ZBrush exports polypaint color information within the .obj file in a rather large mess of hex color codes. I am rendering this particular model with Blinn-Phong style lighting from within the Cuda kernel. 

I will be focusing on optimising what I have right now for the next week or so. I should be able to increase the detail and frame rate quite a bit.

Renderer ported to CUDA

Here is the same setup running in CUDA. I am using a recursive traversal algorithm.

1024x768 - 180 fps - SVO Depth (20)

1x GTX 580

A little more interesting this time.

The smallest Subdivision level shown above is only one millionth the size of the whole octree. A 1km x 1km x 1km scene subdivided 20 times would result in voxels of size 1mm x 1mm x 1mm.

Getting the Directx 11 / Cuda interoperability working was fairly straight forward. I also optimized the traversal algorithm so that it would traverse the voxel hierarchy in order from front to back.

My next goal is to write a converter that will take a high polygon count (~5 million) .obj exported from ZBrush with vertex color information, and compile a sparse voxel octree from this data. From there, I will attempt to load this data into my renderer to see how it performs rendering a single ~5 million voxel model.