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Rasterization also requires "acceleration structures," kept in memory. I could be wrong here, but I think the point John was trying to make was that there was

by cmccabe 14y ago

Rasterization also requires "acceleration structures," kept in memory. I could be wrong here, but I think the point John was trying to make was that there was again a constant factor handicapping ray-tracing. But constant factors are, well, constant, and in 2050 we may well have ray-tracing done in hardware delivering scenes that are indistinguishable from reality. I wrote a ray tracer once, but it was primitive. So I'm not completely talking out of my butt, just mostly.

gsg 14y ago
Rasterisation doesn't require any real acceleration structures. There are various caches, but nothing comparable to a kd-tree or BVH.
dualogy 14y ago
> Rasterization also requires "acceleration structures," kept in memory Yeah but surely not for the geometry itself. In rasterization, we may use simple low-overhead acc. structures to efficiently traverse a relevant sub-set of the whole (but coarsely described) scene for some fancy culling, collision detection (OK that's not really rendering) ... but geometry (vertices, polygons, vertex attributes) does not need to be traversed like that and thus does not have to be stored as individual triangles in an octree or bounding-volume hierarchy or what not. Quite a difference in overheads here. In GPU terms, with rasterization you have geometry neatly stored in vertex buffers and an awesome Z-aware traversal method with vertex shaders. In a simplistic current-gen fragment-shader-based raytracer, each pixel traces a ray traversing through your acceleration structure which may be stored in a volume texture (ouch, so many texel fetches...) since vertex buffers are not sensibly accessible in a frag shader. > scenes that are indistinguishable from reality This would also require a high dynamic range output device. Looking directly into perfectly raytraced sunlight still won't glare and blind me like the real world does, but indeed, by 2050...
- yk 14y ago
  > This would also require a high dynamic range output device. Looking directly into perfectly raytraced sunlight still won't glare and blind me like the real world does, but indeed, by 2050... You could try to look directly into a beamer instead of onto the screen, if glare is all you want. ( And by 2050 I would suspect that the scene is directly copied into the frontal lobe, bypassing the visual cortex.)

by cmccabe 14y ago

gsg 14y ago

Rasterisation doesn't require any real acceleration structures. There are various caches, but nothing comparable to a kd-tree or BVH.

dualogy 14y ago

> Rasterization also requires "acceleration structures," kept in memory Yeah but surely not for the geometry itself. In rasterization, we may use simple low-overhead acc. structures to efficiently traverse a relevant sub-set of the whole (but coarsely described) scene for some fancy culling, collision detection (OK that's not really rendering) ... but geometry (vertices, polygons, vertex attributes) does not need to be traversed like that and thus does not have to be stored as individual triangles in an octree or bounding-volume hierarchy or what not. Quite a difference in overheads here. In GPU terms, with rasterization you have geometry neatly stored in vertex buffers and an awesome Z-aware traversal method with vertex shaders. In a simplistic current-gen fragment-shader-based raytracer, each pixel traces a ray traversing through your acceleration structure which may be stored in a volume texture (ouch, so many texel fetches...) since vertex buffers are not sensibly accessible in a frag shader. > scenes that are indistinguishable from reality This would also require a high dynamic range output device. Looking directly into perfectly raytraced sunlight still won't glare and blind me like the real world does, but indeed, by 2050...

yk 14y ago
> This would also require a high dynamic range output device. Looking directly into perfectly raytraced sunlight still won't glare and blind me like the real world does, but indeed, by 2050... You could try to look directly into a beamer instead of onto the screen, if glare is all you want. ( And by 2050 I would suspect that the scene is directly copied into the frontal lobe, bypassing the visual cortex.)