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Where is it possible to find Earth surface geometry data? (self.askscience)
submitted 2d ago by Budanccio
I'm interested if there are available sources of geometrical info for the surface of the Earth. Something like point clouds or stl files.
CrustalTrudger 401 points 2d ago
I'm going to guess by "geometrical info for the surface of the Earth" you mean topography? By far the most standard way this data is available is as digital elevation models (DEMs) which are gridded rasters where each "pixel" in the raster stores the bare earth elevation representative of the footprint of that pixel. DEMs are distinct from digital surface models (DSMs), where DSMs are typically also rasters storing single elevation values representative of that pixel, but where that elevation includes buildings, trees, etc. There are also digital terrain models (DTMs), but this is *usually* just another way of referring to a bare earth DEM. A variety of global and regional DEMs exist with a wide array of resolutions (i.e., pixel footprint size). A pretty commonly used global one is SRTM (shuttle radar topography mission) that is released with either a nominal 90 m or 30 m grid size, but there are a variety of others (ALOS, Copernicus, etc.). There are some global DSMs as well (e.g., the Copernicus data is releases as either a DSM or a bare earth DEM where "non-ground" data has been removed/patched). Whether a DEM or DSM, these are usually provided in one of a few different file formats, typically GeoTIFFs. GeoTIFFs can be converted to stl files in a variety of programs.
In terms of actual point clouds, it's uncommon to release global data this way. There are specific areas for which lidar surveys have been done where point cloud data is available, but it's still more common to access the gridded DEM or DSM produced from those point clouds.
There are lots of different data clearinghouses for these datasets. A convenient one that has both global and regional gridded and point cloud datasets is OpenTopography.
In terms of actual point clouds, it's uncommon to release global data this way. There are specific areas for which lidar surveys have been done where point cloud data is available, but it's still more common to access the gridded DEM or DSM produced from those point clouds.
There are lots of different data clearinghouses for these datasets. A convenient one that has both global and regional gridded and point cloud datasets is OpenTopography.
Budanccio [OP] 119 points 2d ago
Thank you, I appreciate the detailed response, it's exactly what I was looking for.
bigbadbutters 29 points 1d ago
Google Earth has this available. I use the information there to 3d print topographical maps of states, counties, parks, etc.
DanYHKim 13 points 1d ago
Putting in my 2 cents. Back when I used Google SketchUp, you could place a model into a location on Google Earth, allowing you to account for topography when modeling a building. It was a fun feature to play with.
pmp22 12 points 1d ago
How can you get the data out of google earth?
bigbadbutters 16 points 1d ago
I draw a polygon around the area I want, then save/download it, run that through a conversion tool, then put that into a slicer
FuneralTater 3 points 1d ago
If you're looking in the US, the USGS provides a 1m DEM in the national map.
FoxxMD 1 points 21h ago
> stl files
This site provides a super easy way to generate an STL for any rectangular area on the earth. For the USA it gets to 10 meters of resolution.
https://touchterrain-beta.geol.iastate.edu/main
I've used it for a few projects to 3d print high resolution models of metropolitan areas.
This site provides a super easy way to generate an STL for any rectangular area on the earth. For the USA it gets to 10 meters of resolution.
https://touchterrain-beta.geol.iastate.edu/main
I've used it for a few projects to 3d print high resolution models of metropolitan areas.
hertzzogg 16 points 2d ago
Also, check your local and regional government and environmental services websites.
For instance, here in Texas, TNRIS houses huge data sets.
For instance, here in Texas, TNRIS houses huge data sets.
formerlyanonymous_ 11 points 1d ago
And NOAA typically has not just TNRIS, but most of the publicly available datasets in the USA, including underwater bathymetry.
Several countries are much more closed in terms of access, or at least require payment, which is why you see SRTM used so much globally.
Several countries are much more closed in terms of access, or at least require payment, which is why you see SRTM used so much globally.
fatcatfan 6 points 1d ago
DTM, at least in my experience, usually refers to a triangulated surface model, or the raw information - points and breaklines - to construct such a model. Triangulated models can have irregular point spacing rather than on a grid, allowing for reduction of point density in relatively uniform or non-critical terrain, or increasing point density where needed.
CrustalTrudger 10 points 1d ago
This is why I said *usually*. DTM basically means DEM in most places, but in the US it refers to something different (i.e., what you're describing), see page 48 of the USGS Lidar Base Specification document, specifically:
>digital terrain model (DTM) See two different definitions below:
>• In some countries, DTMs are synonymous with DEMs, representing the bare-earth ter-
rain with uniformly spaced z-values, as in a raster.
>• As used in the United States, a “DTM” is a vector dataset composed of 3D breaklines
and irregularly spaced 3D mass points, typically created through stereo photogram-
metry, that characterize the shape of the bare-earth terrain. Breaklines more precisely
delineate linear features whose shape and location would otherwise be lost. A DTM
is not a surface model and its component elements are discrete and not continuous; a
TIN or DEM surface must be derived from the DTM. Surfaces derived from DTMs can
represent distinctive terrain features much better than those generated solely from grid-
ded elevation measurements. A lidar dataset combined with ancillary breaklines is also
considered a DTM
>digital terrain model (DTM) See two different definitions below:
>• In some countries, DTMs are synonymous with DEMs, representing the bare-earth ter-
rain with uniformly spaced z-values, as in a raster.
>• As used in the United States, a “DTM” is a vector dataset composed of 3D breaklines
and irregularly spaced 3D mass points, typically created through stereo photogram-
metry, that characterize the shape of the bare-earth terrain. Breaklines more precisely
delineate linear features whose shape and location would otherwise be lost. A DTM
is not a surface model and its component elements are discrete and not continuous; a
TIN or DEM surface must be derived from the DTM. Surfaces derived from DTMs can
represent distinctive terrain features much better than those generated solely from grid-
ded elevation measurements. A lidar dataset combined with ancillary breaklines is also
considered a DTM
c_birbs 1 points 1d ago
You can access point clouds, prob is the software to exploit it. Think there is a free version of QT, but it’s only for viewing the data, no exploitation tools.
CrustalTrudger 1 points 1d ago
There are reasonable solutions out there. CloudCompare allows some processing along with visualization. The free portions of LAStools also has decent functionality for doing some base level processing of point clouds.
ShakaUVM 8 points 1d ago
NOAA used to have easy to access height map data at like a 1km resolution for any grid you can select on the planet. It was just an ASCII file so super easy to work with.
Now they only export in GIS formats, dunno why.
Now they only export in GIS formats, dunno why.
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