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phd

Ray / Octree traversal: Parametric Algorithm

I’m implementing my current ray-octree intersection algorithm using an adapted version of the Revelles 2000 paper An efficient parametric algorithm for octree traversal, and after some painstaking debugging, I think I found a bug in the paper’s text. which seems to be acknowledged in this 2005 google groups discussion as …

Ray / Octree traversal

Since the basic work on my voxel raycaster is finished (Crunching voxels with 3D DDA – generalized Bresenham – in a 3D array), it’s time to start looking at hierarchical structures and the methods of switching between several Levels of Detail, which is the direction my PhD will be heading …

Voxel Raycaster: Enter the Stanford zoo

If you’ve looked at some computer graphics literature before, you’ve probably noticed that a lot of models are used over and over again, like the Utah Teapot. Last days, I’ve been working on import functions which allow me to load the Stanford standard benchmark models in and render them, voxelized. …

So what is a voxel, really?

When reading about volume rendering on the internet, I discovered an irritating fact: there is no consistent definition of what a ‘voxel’ is. Most certainly when it comes to various rendering engines, everything that renders something which contains cubes/blocky elements gets the voxel renderer tag hastily slapped on. A good …

It’s alive!

First rough video of my current Voxel Renderer implementation. It’s nothing too exciting, just showing that the Proof Of Concept actually works in real-time. The flyby is on the edge of the voxel field, since inside it’s just … trippy. This is a 512x512x512 field with 8 bytes per datapoint …

The 32/64 bit DLL confusion on Windows 64-bit

Since I’m developing my PhD renderer for multiple target systems (Win32, x64, LInux, …) I started using the excellent freeGlut project for simple OpenGL windowed output. So after finding the Windows binaries compiled (and maintained) by Max Martin Payne, I look at the contents of the zip file. I was …

Voxel Renderer: Spheres and Boundaries

During the last days, I’ve been testing just how much my current renderer implementation can take. My implementation was started from scratch, based on raycasting (eg … interpolating distinct values along a line) in a huge data grid. At the moment it is without any optimization for quick free-space skipping, …

Voxel Renderer: Parallellism is key

I’ve implemented a stable version of the Amanatides and Woo algorithm for fast traversal of voxel grids and added some optimisations and support for non-square voxels. After reading up on OpenMP, I couldn’t stand having a renderer which ran an inherently parallel algorithm on just one CPU. Every ray shot …

Voxelicious

I’m going to run out of voxel-based titles and puns real soon. Until then, have some more flying cubes! The sparseness factor influences render time a lot, since there is no efficient skipping of empty space inside the voxel grid. So denser grids render at interactive framerates (>30 fps), because the …

Voxel Renderer: Sparsity

Once the basic stuff was in place, it was fairly easy (half a day’s work) to implement a renderer which supports sparse voxel fields. Next step is opacity. Generating one image at 600×600 with 64x64x64 voxels in place renders at 15 fps, but that’s without any optimization. For example, there’s …