On 02/10/15 01:06, David Given wrote:
[...]
> I enclose three more pictures; this is the same scene, taken from about
> 25km up, in twilight, dawn and daylight, respectively. They took a
> drastically different amount of time to render; the daylight one was 235
> seconds, while the dusk one was 1320.

Hey, guess what --- meshes are so much faster than isosurfaces! Who
knew? (Apparently everyone except me.)

Enclosed is an updated version of the dawn picture; all the settings are
the same, except instead of using isosurfaces for the terrain and ocean,
it's now using meshes. Total render time is 195 seconds (115 for the
parse, which includes the mesh generation, and 80 for the render).

The isosurface version took 715 seconds.

And this version has the procedural deformation on the terrain turned
on, so it's actually doing more work.

The meshes are about 5 million polygons each. The polygons are scaled so
there are ~800 horizontally across the picture, regardless how far away
they are. These are generated by my DLL stuff and the mesh handed
directly to Povray (which immediately takes a copy of it, and then takes
another copy, but never mind). Interestingly the slowest part of the
process is Povray thinking about the mesh after I've passed it the data.
Is it generating a bounding box octree? If so, it's working, because the
rendering is amazingly fast...

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