Workflows for Textures from Image Depth Maps

[RAMilewski]

This discussion is about currently available workflows for producing depth maps from image file prior to generating texture data arrays. Please join the discussion and advise of any tools you have discovered for producing depth maps from image files.

[RAMilewski]

This is an example of a .png image and the depth map that results from processing the image through Sculptok.com.
While a workflow completely on the local machine would be preferable, to date I've not found any with comparable results.
See Textures from Graphic Images for an example of this depth map used on a textured_tile().

[RAMilewski]

On-Line Depth Map Generators

SculptOK - Subscription model but you can purhase non-expiring credits. This produces the best results of things I tried thus far.

Depth-R - Free depth map generation with a daily limit. Mentions downloadable apps for Windows and MacOS, but they appear to be tied to monthly subscriptons.

Vondy - Make what appear to be ok on-screen depth maps, but seems to require a monthly subscription to enable downloads.

[dan-p3rry]

Hi, did you make the globe in the Skin documentation? I'm really struggling to duplicate it, starting with exactly what data to download from earthdata. From the link in the documentation, I'm unable to download (I have an earthdata account). From search.earthdata.nasa.gov, I cannot find any single file that contains SRTM data for the planet. Do I need to download almost 2 million files to make my own geotiff file? It would be great if you could provide more info on the flow. Thanks!

[RAMilewski]

That was done by Alex (@amatulich). The data file is worldmap_360x180.scad in the examples folder.
SRTM data isn't what you want. It only covers about 80% of earths surface. It's better for more detailed relief maps of smaller areas.

If you look at the comments in geotiff2scad.py you'll find sources for additional full-planet data. Not only for earth but for the moon and other planets.

[amatulic]

@dan-p3rry - You need a .tif format called "geoTIFF". Then geotiff2scad.py can scale the data and convert it. In the case of the earth data, the script by default accentuates coastlines by raising the minimum land elevation by 3% of the total elevation range, and reducing sea level by the same amount. If you don't do that, then low-elevation features like the Florida penninsula disappear when scaled to pixel brightnesses with the comparitively narrow range of 0-255. The elevation is also scaled by the cube root of the actual elevation, which is standard for relief maps. This accentuates the variability in low-elevation features while somewhat flattening the high elevation features.

[dan-p3rry]

@amatulic @RAMilewski
Thanks for the excellent explanation of how to process the geoTIFF to accentuate coastlines, etc.

I downloaded worldmap_360x180.scad, but I don't know what to do with it. From context in the documentation, it seems I should apply it using textured_tile() but there are no examples using spheres, so maybe not.

OpenPlanetaryMap is probably not worth listing as a reference, mostly everything is placeholders, very little real data. And I would love to know exactly what data you downloaded for the earth elevation geoTIFF. I've spent hours on search.earthdata.nasa.gov and not finding (or not recognizing) the correct data.

Thanks again...

[RAMilewski]

include<BOSL2/std.scad>
include<BOSL2/examples/worldmap_360x180.scad>
$vpr = [70,0,-360*$t];
color("blue") spheroid(20.007, $fn = 256);
rotate_sweep(arc(r = 20, n = 129, start = -90, angle = 180), 360, 
    texture = worldmap, tex_depth = 0.5, tex_reps = [1,1]); 

I'm working on a texturing from images tutorial, but it will be a bit yet.

[amatulic]

@dan-p3rry - I got the geoTIFF data from here: https://www.ncei.noaa.gov/products/etopo-global-relief-model - I downloaded the 60 arcsecond ice sheet data. Then I used geotiff2scad.py to convert it to a png file (that script converts geoTIFF to 3 different formats including .scad). You can use img2scad.html to convert the png file to a lower resolution and perform some image processing if needed.

[dan-p3rry]

Thanks! That website is a great resource. I got really nice results with the 30 arcsecond data and higher resolution from geotiff2scad.py. I'm diving deeper, will let you know how it goes.