Update 2:
I just upadated the links for the Japanese Alos site (plus an added link for the free registration).
Cheers, D

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Hi there,

Yes, there is a new Houdini category. 🙂
As I learn Houdini I’ll try my best to give a few useful tip for beginners (I’m not an advanced user in Houdini so if you have any advice – related to the that specific topic – feel free to share that information).

Cheers, D

Create Terrains form Elevation maps in Houdini

Where to download elevation maps:

• The best place to download elevation data is the Japanese Alos site. 
  Registration link (free): Registration link
  You can register for free at the download section.
  The actual download page.
• Select a large area, than a smaller one. You can download a 5 by 5 area at one click or each tile separately as a GeoTiff file (the DSM named files are the elevations the MSK named are water mask).
  Size: 3600 px by 3600 px.
  Real world resolution: each pixel is 30 m by 30 m (approximately at the equator). You may want to correct the proportions caused by the actual projection type based on the Tissot’s indicatrix.
•  

In Houdini:

This is a very simple thing to do in Houdini. As always there is a lot of way to to this, but this is the most simple one (an precise as well).

1. Create a HeightField object (go inside)
   Change the Division mode to By Axis, this way you can control the resolution better.
   Grid Samples: 3600
   Size: 3600 and 3600
2. Add a HeightFiled File node.  Select the downloaded tif file.
   Change the Layer Name to height (to get elevations not a mask).
   Size, Size: 3600
3. Add a HeightField Remap node. Because how the data stored you have to remap the height values this way (you’ll get correct elevations but you have to divide it by 30 because earlier we did’t scaled up the size of the terrain in XZ):
   Input Min: -1
   Input Max: 1
   Output Min: -32768/30
   Output Max: 32768/30

That’s it 🙂

Of course the correct number is 32768. Sorry. 🙂

A few things:

• If you want a smaller peace of the terrain you just have to change the Size parameters at the HeightField node (for example 1000 by 1000) and change the center X and Z.  You may want to lower the resolution accordingly.
• After the you created a base you can modify it with the usual Height Filed nodes.
• You can upscale the whole terrain to get 1:1 sizes with the HeightField Transform node (Uniform Scale: 30).
• You may have to correct a few data error with an image editor software (simple way). Errors are usually at the non interesting part of the image outside the actual terrain (oceans).

Update!

There is a simple way to remove the incorrect data (too bright pixels) in Houdini:

• Select the heightfield_file node
• RMB -> Allow Editing of Contents
• Open it
• Go inside the cop2net node at the top and open it
• Put a limit node between the File node and the switch node
  • Set the lower limit to: -0.5 (so you will keep the data under the see level)
  • Set the upper limit to: 0.5 (so you clamp the data at half of the maximum possible value, it’s more than enough)
  • Clamped Values: Replace with Black (usually the too bright values were originally at the see level)

That’s it.

Cheers, D