Creating maps from satellite data

Miner34

Car destroyer and modder
Joined
Mar 23, 2024
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This tutorial will show you how to create a map starting from satellite data.
First of all head your browser to portal.opentopography.org/datasets.
Once there, your screen will look like this:
Screenshot_20240401_122347.png

Zoom in to the area you want to import (if you are having issues finding it, try changing map type).
Once there, click on the "select a region button".
Drag to select the area you want (in this example i selected the Garda lake in Italy).
Screenshot_20240401_122952.png

The site will automatically scroll down to show the datasets you can use for that area.
Choose one with a decent quality and a license that allows this use.
If you are grabbing a piece of USA just use the USGS 10 meters.
In this example i'm going to use Copernicus 30 meters.
Screenshot_20240401_123942.png

Once clicked, it will show you the area you are downloading one more time, this time also telling you how big it is.
Do a screenshot of/write down somewhere all the data related to the coordinates.
EDIT: Not fully needed as the .prj file together with the terrain itself contains this data in text format.
Screenshot_20240401_124656.png

Set the data format to Arc ASCII Grid.
Screenshot_20240401_124305.png

Insert your email (will be needed to notify you once it has finished) and click submit.
You can now close the tab.
Shortly after clicking submit you will receive an email containing the link to the file.
It will look like this:
Code:
OpenTopography.org - A Portal to High-Resolution Topography Data and Tools

Thank you for using the OpenTopography Raster System.

The results of your job (ID: rt1711968518850)


are available at
https://portal.opentopography.org/result?id=rt1711968518850

Metadata about your job are available at
https://portal.opentopography.org/result?id=rt1711968518850&metadata=1

Dataset Citation: European Space Agency, Sinergise (2021).  <i>Copernicus Global Digital Elevation Model</i>.  Distributed by OpenTopography.  https://doi.org/10.5069/G9028PQB. Accessed: 2024-04-01

Use License: © DLR e.V. (2014-2018) and © Airbus Defence and Space GmbH 2022 provided under COPERNICUS by the European Union and ESA; all rights reserved.

If you are a registered user of OpenTopography, you can also access the results of your job via the 'Raster Jobs' link under the myOpenTopo Workbench section of myOpenTopo. Please note that the results will expire after 48 hours.

----- The OpenTopography Team -----
Note that the file will be a tar.gz archive (i think you need 7z under Windows).
Well, for now it's enough, the next time i will show you how to import it in Blender and finally in Rigs of Rods.
 
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Once you extract the archive you will need two files: a .asc (the terrain) and a .prj (metadata about the terrain). Both can be opened with a text editor. You will see that the .asc is just a bunch of coordinates, while the .prj can be readed from an human easily.
This is my .prj:
Code:
GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]
Now, let's import our terrain in blender. You will need Blender, of course (version more recent than 2.83) and the BlenderGIS addon.
Once you start blender, you will have the default scene. Press A and then X to delete every object in the scene.
Click on on the import .asc button and select your file.
Screenshot_20240403_120211.png

It will take some time, especially with high quality/large terrains.
After loading, you will probably end up with... a weird super high object with almost no thickness.
Screenshot_20240403_122715.png

Don't worry, it can be fixed.
Just change the scale in a way that the X and Y axis are 100'000 times the Z axis (the scale, not the dimensions!).
Be careful to make sure you can see the whole thing (don't make it too small or big).
Screenshot_20240403_123452.png

Here we go! Now you have the terrain in Blender!
Well, for now it's enough. Exporting to Rigs of Rods will be for the next time.
 
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