Dom's Blog

Last august I finally took some time to try an idea I had or a while (years?). Would it be possible to mis-use 3DVIA Virtools Point-Cloud system for rendering foliage objects (grass, flowers, plants etc). Basically, Point-Clouds are used to visualize 3d scans or data. It's a feature that was slowly introduced with 3.0 Service Packs and finalized in 3.5.

It comes with a feature that is called "Point Cloud Selection" which allows to render separately a subset of the cloud. Interestingly you can also render meshes instead of sprites. This, plus being able to use shaders with point clouds gave me the idea that it might be useful for outdoor foliage rendering.

I'll make it short: it doesn't work the way I hoped.

If you try to render a selection with meshes using a shader, the whole system slows down intensively. I think it's a combination that was not considered or intended by the developers. So it's only compatible with the fixed function GPU pipeline. Besides that I am not sure what it takes to calculate the vertex positions inside the shader correctly, so a mesh is rendered at each point position.

In addition to that, the bigger the cloud is, the slower is the selection process itself. Thus you cannot have one point cloud for your entire outdoor scene – you would have to manage multiple clouds via a grid, nullifying somehow the benefits of this out-of-the-box selection-system.

Here is a picture where on the left you see the whole point cloud and on the right you see a circular selection around the character:

Of course, there are other methods to do the same. Justed wanted to see if it goes also like this. 🙂