Comment by cubefox
1 day ago
No? Each pixel on a height map corresponds to a column of voxels of the specified height. You could represent the same height data with a fully general octree and it would look exactly the same.
1 day ago
No? Each pixel on a height map corresponds to a column of voxels of the specified height. You could represent the same height data with a fully general octree and it would look exactly the same.
It's kind of weird to call them "columns of voxels" when the columns can't have gaps and the "voxels" below the topmost are ignored completely. Which is to say, they're just columns...which is (definitionally) just a height map.
In fact, an octree for this approach would be _meaningfully worse_ because finding "the topmost voxel" in each column is O(logn)—or maybe worse?—versus O(1) for a height map. With no benefits, because you never look at any other voxels.
Voxel below topmost were not „ignored completely”. They were absolutely rendered in e.g. steep cliffs.
> It's kind of weird to call them "columns of voxels" when the columns can't have gaps
No, it's not weird. The columns don't have gaps because they are columns represented by a height map, which can't display arbitrary voxel geometry (unlike octrees), but that doesn't mean they can't display voxel geometry at all.
> Which is to say, they're just columns...which is (definitionally) just a height map.
Yes. A height map is representing voxel data without overhangs.
> In fact, an octree for this approach would be _meaningfully worse_
That's irrelevant. The fact remains that rendering the same height data using an octree would look exactly the same. If the latter displays voxel geometry, the former does too.
> A height map is representing voxel data without overhangs.
A height map can represent voxel data if the columns are integer heights, in the same way an integer can "represent" an infinite number of countable things. It's like saying the number 7 is "related" to a group of 7 ducks. The relationship is kind of meaningless.
But more importantly height maps can use also floating point heights in which case there's no reasonable mapping between the two. So your statement isn't generally true.
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Your argument comes down to the meaning of "voxel", then. Voxels have volume, and they are represented with polygon faces. If you think that applies here, I guess more power to you.
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