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Comment by GrandMasterBirt | Hacker News Reader

Hey makes perfect sense, why calculate for any point that is not visible.

I wonder if physics calculations play into this.

This happens with polygonal renders, too - it's called occlusion culling.

The problem is that point clouds can't be easily animated, and forget about applying physics to them, which makes them fairly useless for realtime gaming.

Exactly, notice no collision detection or animations were demonstrated. Also didn't see anything really beyond some shader effects and a single point light.

why is that these point clouds can't be easily animated, are the data structures that allow for the searching too difficult to update once they've been built or is there just too much data to process?

(disclaimer - I'm not an expert) They're probably using some kind of sparse octree for looking up points. That means they split the space with planes into areas with high concentration of points and empty ones (then split the full ones more). These kind of structures are not easily update-able as far as I know - or if you update them in trivial way (move the boundary), they could lose the fast lookup properties. It's a bit like with global illumination - you have to precalculate a lot of values to render the scene in a reasonable time later on.

It would be interesting to see if anyone can create a hybrid of point-cloud scene + polygon animation... should be enough for most shooters. (Outcast apparently had something like that, but that was pre-"nice graphics")

Outcast had voxel grass, Worms 3D used voxels for destructible scenery, and most recently Crysis used voxels to create caves and such in the terrain.

Although I'm pretty sure point sprites and voxels are two different things.

What about for rendering 'virtual reality,' Quicktime3D type environments? Like to give people virtual tours over the web.

Games and graphics look great nowadays, the need to do something just for the tech is not a real driver. Why would someone invest the time in this and static when they can also add interactivity? Until it can do interactivity, real-time, lighting, animation, collision detection/physics, etc better, faster and stronger, it will not take the market for graphics.

Well one thing I was thinking about is this 'laser-scan' technology for modelling real world objects. Perhaps the appeal of a quick, light, easy method of rendering detailed environments (albeit static) will prove very popular. Usually when I see static 3D demos on television (for instance on Grand Designs, a new-build architecture show, or computerized replays in soccer), they meet the bare minimum in aesthetic appeal.

Exactly when he mentioned the pixels of a screen and only rendering for them, he made it sound new with his voice but it is just culling and z-buffering. Point clouds still have to do that.

The reason why we use polys is for eliminating the math of all those points to make physics, shadows, texturing possible. I can see voxels/point clouds will be something in the future and voxels will probably be it, but this is silly to present static low quality work to show off a new technology for graphics.

I wonder if it is not a joking jab at tessellation and voxel directions as DX11 and OpenGL 4 now have tessellation and voxel discussion by Carmack. It will happen but these things are slow moving.

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