The entire workflow:

• Part 1: Download elevation data as an image, preparations (editing)
• Part 2: Generate a terrain from texture (WorldMachine)
• Part 3: Modify the terrain in WorldMachine
• Part 4: Generate the additional textures from the modified terrain in Substance Painter/Substance Designer
• Part 5: Create the scene in Maya/Arnold

Part 1:

Download elevation data as an image, preparations (editing)

• You can download data as images (16 bit/channel GeoTIFF file) here:
  https://gdex.cr.usgs.gov/gdex/
• You have to register via the log in button (NASA Earthdata)
• Select the area you like (Define Rectangular Area) -> click the download button
• Select the format and usage
  • Aster Global DEM v2
  • GeoTIFF (if you choose GeoTIFF – 1×1 Tiles you’ll get multiple square images and each tile is 3601×3601 px)
  • you can download it as a compressed zip file as well
  • Choose the Reasearch Area
  • Click Submit
    
• You’ll get a preview and some really important data
  • write down all the data. It’s important!
    I usually just create a print screen 🙂
    
    

    
• About the texture:
  • You can open the image in almost any image editing software
    (I recommend Affinity Photo. In Photoshop you don’t get accurate grayscale values. Really strange.)
  • Each greyscale value equals 1 m elevation (above the see level)
  • 1 pixel = approximately 30 m (at the equator!)
• Usually the texture came with an unnecessary one pixel wide (or one pixel high) pixel-column (or row) at the edge of the image
  • Crop the image to resolve that issue

Two simple way to use it

• You can use that image directly in Maya after some exposure correction
  (You cannot use the file node’s exposure attribute inside Maya 😦 )
  • In the image editing software:
    Add an exposure adjustment layer and set the value to get a nice looking texture
  • Use the histogram to avoid cilpping
  • Use the Save As… (in Affinity: Export…) command to preserve the original image

Version 1: Texture Deformer

• Create a polyplane with high subdivision values
• Set the size (don’t forget: 1 unit is 1 cm)
• Add a Texture Deformer to it
• Connect the texture
• Set to Raw (file node)
• Turn off Wrap U and Wrap V (place2dTexture node)
• Set the Strength value (textureDeformer node) – it depends on the actual size of the polyplane and on the texture itself
• You may have to adjust the Offset value
• Usually you have to edit the UVs a bit. In the UV Editor execute a Layout command with Tile Padding = 1 px

Version 2: Dispalcement

• Connect the texture to the shader’s SG (shadingEngine) node via a displacement shader
• Activate the displacement preview in Viewport 2.0
  ALT+3
• In the mesh node you have to set the Subdivision level. (Arnold section -> Subdivision ->Iterations). Set the type. Don’t forget, you already have some subdiv level (the default is 2) with the Alt+3 preview.
  Displacement preview + Arnold’s subdiv level = total subdiv level
• Set the displacement Scale as you like it
• You may have to adjust the Bounds Padding attribute
• The displacement preview is accurate only if you use true 16 or 32 bit/channel grayscale images as displacement texture

To be continued…

Cheers, D

p. s.

Here is the Tissot’s indicatrix for texture scale corrections: