Global DEM resolution test

[bigben]

Running a quick test on the resolution of my global DEM and the resources required.
Basic TGD with 3 surface shaders ("water", green and "snow"), displacement multiplier 1.7, Detail 1, AA 4

[attach=1]
0.005°/px 16.3Gb RAM to render, 7m 15s

[attach=2]
0.02°/px Altitudes generally lowered from resampling. 6.7Gb RAM to render, 6m 30s

For reference: SRTM resolution is 0.00086°/px

[bobbystahr]

uh,,,,,WOW...for lack of anything else to say which has meaning.

[Mahnmut]

Impressive!

[Oshyan]

Hehe, I love that the higher resolution did not take significantly more render time, just more memory. Nice also to see that at this height the 0.02° data actually does pretty well, aside from the height differences. Is there any way to compensate for that with different resampling algorithms, or rescaling heights after downsampling?

- Oshyan

[bigben]

It's a little tricky as plains would still be at the right altitude, it's just the sharp peaks that get smoothed out.  Probably easiest just to alter the values for the altitude restrictions or use the displacement multiplier to stretch things back out a bit. It's very nice that render times don't increase much with bigger files.

[Dune]

Hi Ben,

A question; do you know if any underwater DEM's are available? I get the impression they only cover land down to the water line.

[bigben]

My global DEM includes bathymetry    The main data sources I've used are:

GEBCO http://www.gebco.net/
GMTED-2010 http://topotools.cr.usgs.gov/gmted_viewer/
SRTM4 http://srtm.csi.cgiar.org/

I've stacked them in that order, so the highest resolution data is used where available, with SRTM being about 6X the resolution of my biggest DEM. To make a flat ocean with a single planet requires some masking of the DEM. 

[Dune]

That's good to know, thanks Ben. I don't know yet, but Dorian will in due time; we might need some bathymetry data for the Red Sea.

[bigben]

 Will send you a file you can use before (underneath) the SRTM DEMs. Will PM in the morning when it's transferred.

[Dune]

Thank you, Ben.

[bobbystahr]

I just love this forum...the most helpful place I've hung out since early Imagine3D daze...y'all are really good people with excellent taste in terrain making programs.....