I need to know for example, heights of bridges/fly-overs from the land surface (just to know there is an elevated structure). How and where from can I get this data (preferably for EU)? Any open source databases/ any 3d maps with this data?
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Just to confirm, you're looking for more than just topological elevation data, correct? You could figure out elevated structures from topological data, but you're look for a source that's already done this, correct?– user3856Jan 15, 2016 at 16:27
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Yes, I was looking or elevation data of human constructions(more specifically road and bridge elevation data). No, from what I gather, topological data only gives me land elevation. Using google maps, I can visually determine an elevated platform/road but can not see any change in the elevation height on that platform and a point just next to the platform on the land surface. Please correct if I am mistaken.– user750066Jan 16, 2016 at 17:20
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When I used a .BIL file to map Albuquerque's elevation, the raised highways (I25 and I40) were clearly visible, so I think topological data (at least the kind I've found) does include structural height, since it considers the top surface of a structure as "land". Of course, you need fairly high resolution to see the smaller structures.– user3856Jan 16, 2016 at 17:48
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Hello Barry, Can you help me with the source for the .BIL files ? Do yu use some professional maps? Else if the bin resolution is 30m*30m, I cant understand how would elevation data for that bin help differentiate between an elevated road and the land surface...– user750066Jan 17, 2016 at 19:02
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for England there is Lidar (DTM/DSM) up to 50cm resolution more info environment.data.gov.uk/ds/docs/… but you can extract height information out with some GIS software processes bases on it's refective properties (concrete can be detected).– MapperzFeb 6, 2016 at 19:55
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1 Answer
There appears to be a US government program to map structural heights, suggesting that such a thing isn't already available. Quoting http://nationalmap.gov/3DEP/
The 3D Elevation Program (3DEP) initiative is being developed to respond to growing needs for high-quality topographic data and for a wide range of other three-dimensional representations of the Nation's natural and constructed features.
You can find existing elevation data at:
http://viewer.nationalmap.gov/basic/?basemap=b1&category=ned,nedsrc&title=3DEP%20View
or by clicking on the "Get Elevation Data" link at http://nationalmap.gov/elevation.html
The maps here are 1/9 arcsecond per pixel, which is right about 10 feet per pixel in latitude.
http://nationalmap.gov/3DEP/3dep_prodavailability.html notes that you can get 1m (about 3 feet) resolution digital elevation maps; however, it appears that this data isn't available online and that you must make a special request for it.
Of course, you're looking more for EU data. The US government does have some of this too: https://lta.cr.usgs.gov/elevation.html and http://hydrosheds.cr.usgs.gov/data.php but it seems even the best such data is 3 arcseconds, or about 90 feet per pixel, which might be enough to miss structures.
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Hello Barry, thanks for the message, I downloaded map files from store.usgs.gov which turn out to be pdf files. These are not really helpful as I still can not access the elevation measurements of constructions(elevated roads, etc). Am I missing something? Or does it being me to what you quoted: 3D topographic elevation is under development...? Jan 19, 2016 at 16:48
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Sorry, I meant that is was under development, so such a thing probably doesn't exist yet (since there's no need to develop something that already exists). The data you want to download is from the other sources I mentioned, but store.usgs.gov should have BIL files. Let me know what files you want to download and/or what process you used to get the files. You have to click on the "download" link, not on the name of the map itself.– user3856Jan 19, 2016 at 16:55
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For checking what sort of information is available and whether I could really use it, I tried downloading data from store.usgs.gov by going to "Map Locator & Downloader" and then randomly zooming on to a city, placing a marker, clicking on the marker and choosing one of the latest data sources and then downloading the selection from the cart. (eg.: Stuarts Draft US Topo 7.5X7.5 GRID 2013 30.57MB). All it downloads is a zip file with a pdf in it. Any any chance is it that the data(BIL files) you are talking about is not available from other countries or is restricted? Jan 21, 2016 at 9:58
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My apologies. I've now corrected the links. As a note, USGS is doing maintenance that was supposed to end 5m ago, but may still be in progress, based on the popups I'm getting.– user3856Jan 21, 2016 at 20:06