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ArmA 3 Heightmap Real World Data
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ArmA 3 Terrain Heightmap Using Real World Data
There is big difference between fictionally made terrain heightmaps and real world data, fictional may look cool but real world is the new hot thing for arma3 terrain community.
Please note that real world heightmap data in cities often have lot of bumps and odd elevations which make no sense. Most likely you need to clean and smooth out these wild elevations in cities or other populated spaces.
Someone said that this is because satellite grabs the data, but if the beam (?) hits a city building, the elevation VALUE might be 10-30m higher than actual earth surface because beam returns from buildings roof instead of ground. If someone has scientific facts about this please share.
Best online heightmap data?
At the time of writing this page the best heightmap source is Shuttle Radar Topography Mission (SRTM GL1) Global 30m found from OpenTopography site or from global mapper online sources.
ARC Seconds
1 Arc second is 30 meters
9 Arc second is 90 meters
See also arma terrain DEM resolution.
OpenTopography
This is very good site to download elevation data, it has nice coverage and nice user interface. Remember global mapper online sources includes this same data.
Go to OpenTopography web site, click Global Data tab.
Next you need to choose what data to download. You can see the options below, however we continue here once you have selected one or the other.
Click satellite data → and which ever data you chose to use. Now you should see world map with red boxes marking the areas for available data.
Use mouse wheel (middle button) to zoom in / out of the globe map, LMB and drag to move the map.
Once you have zoomed enough in to a smallish area, click “select a region” button in left side of the globe map screen. Mouse cursor changes to a cross now and you can drag a box to select region. Below you can see the data selection coordinates.
OpenTopography site limits digital elevation map downloads to 450,000 square kilometers (which is huge in arma3 terms).
In coordinates box, if you choose to do so, you can tick “manually enter selection coordinates” box and then manually type in lat/lon coordinates. This is the only sure way to grab perfect square power of two data selection.
Once you are satisfied with your selection, scroll down to data output formats. Choose “Arc ASCII Grid” from the drop down.
On visualization untick “Generate hillshade images from DEMs” box.
Finally on job description box “Enter your e-mail address” just type in whatever asdf@aol.com some fake email address, unless you specifically want them to email you of course. At some point if you try to get huge amount of data that there is long waiting period while site is processing it, perhaps its good way to add your own email here so you get notification when the download is ready. But for normal small size data selections, there is no need for real email.
When fake email is in, click submit.
Once processing is done you get “Raster Job Report” page which has your download. On “Download compressed raster results:” click the “rasters_srtm.tar.gz” (or rasters_alos.tar.gz if you chose ALOS) downloadable file to… you know, download.
This download is always the same file name so please be careful and unpack this file into a directory
Use WinRAR / 7Zip RMB “extract to rasters_srtm/” and then rename the directory to some descriptive name which you easily recognize because the terrain Asc ASCII Grid file inside is also named just “output_srtm.asc” every time you download new data. This way you never overwrite your existing terrain data downloads.
SRTM
Shuttle Radar Topography Mission (SRTM GL1) Global 30m
ALOS World 3D - 30m has a lot of missing data spots. Shuttle Radar Topography Mission (SRTM GL1) Global 30m seems to have better coverage and the data / heightmap quality is much better than alos world 3d - 30m, it is highly recommended you download SRTM instead.
ALOS World 3D - 30m
ALOS World 3D - 30m
Click satellite data → “ALOS World 3D - 30m” to choose this data format. This data is lower quality than SRTM and it actually has some empty spots in it. We would not recommend using ALOS World 3D - 30m data.
Global Mapper ASTER GDEM
You can do Real World Data Global Mapper as it downloads automatically ASTER GDEM data for you if you use the connect to online data button.
US National Elevation Dataset
United States National Elevation Dataset is heightmap with 10 meter resolution which is very good. Unfortunately as the name suggests, its only for America, so unless you are doing american terrain this has no use to you.
https://www.usgs.gov/core-science-systems/national-geospatial-program/national-map
No idea how to download this manually, it can be done using global mapper → online sources → U.S. Data → united states elevation data (NED) (10m resolution).
USGS EarthExplorer
https://earthexplorer.usgs.gov/
Requires login? 
Zoom into area of your liking, use search criteria → coordinates → use map, button to select everything you see in the screen (you should zoom close to your arma3 sizeable area, leave some room to breathe though).
Click data sets button.
Click digital elevation → SRTM → SRTM 1-arc second global.
Click results button.