POV-Ray : Newsgroups : povray.binaries.images : Spherical displacement map : Re: Spherical displacement map Server Time: 26 Sep 2020 15:20:54 GMT
  Re: Spherical displacement map  
From: Bald Eagle
Date: 12 Jul 2020 10:55:01
Thomas de Groot <tho### [at] degrootorg> wrote:

> Impressive. Good work. Depending on the ultimate use, one can opt for
> the bump_map or the displacement_map.

Yes - and believe it or not, the max gradient is less than 3, so it actually
renders surprisingly fast.
The real plan is to convert the elevation of what would normally be a
rectangular heighfield into the radius values for the spherical coordinate
system tiles.
At the very least for the corners and centers of the tiles - so that Everest and
Death valley aren't at the same elevation.   ;)
But while I'm at it, why not do splines for edges, wireframe, and
bezier/triangle mesh.

> The displacement_map looks very
> good: down to what level of detail?

Let's see.
4320x2160 / [180x90] = 12x12 degrees lat/long x ~69 miles per degree
is about 828 miles square = 1332 meters per pixel

So, not terribly detailed, but it does look good - I'm only using 0.01 for a
multiplier of the elevation.   So it can be made much more dramatic   ;)
It's quite rough - like a non-smooth heightfield, which is perfect for
extracting the spline data, but for a displacement map used like this, a 3x3
convolution, Gaussian blur, or something like that could possibly make it look a
bit better.

As far as I know, this was the only way to get a "spherical heightfield".
If there are other ways to do this - I'd love to know!

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