Use an xEdit script to export the raw height data for a worldspace's cells. Then, use the JavaScript-based tool in Firefox to read that data and generate a heightmap image that you can save.
Permissions and credits
Credits and distribution permission
Other user's assetsAll the assets in this file belong to the author, or are from free-to-use modder's resources
Upload permissionYou can upload this file to other sites but you must credit me as the creator of the file
Modification permissionYou are allowed to modify my files and release bug fixes or improve on the features so long as you credit me as the original creator
Conversion permissionYou can convert this file to work with other games as long as you credit me as the creator of the file
Asset use permissionYou are allowed to use the assets in this file without permission as long as you credit me
Asset use permission in mods/files that are being soldYou are not allowed to use assets from this file in any mods/files that are being sold, for money, on Steam Workshop or other platforms
Asset use permission in mods/files that earn donation pointsYou must get permission to earn Donation Points for your mods if they use my assets
Author notes
This author has not provided any additional notes regarding file permissions
File credits
This author has not credited anyone else in this file
Donation Points system
Please log in to find out whether this mod is receiving Donation Points
Changelogs
Version 1.11
File loading: We no longer dump the FileReader to the console, so viewing debug output in browsers with better consoles shouldn't lag/hang anymore.
Version 1.1
Fixed the readout for your current scroll location.
Added a display indicating the brightness-to-world-units conversion factor.
Switched the file loading mechanism to prefer HTML5 FileReader over XMLHttpRequest.
Added a "use strict" directive.
The prior two changes mean that this tool should now also work in Chrome and IE.
CSS fixes to certain flexed elements; the topbar should now have the correct height (Chrome), as should the "Go" button (Chrome, Edge).
Cobb Worldspace-To-Heightmap Converter
I built this tool for my own use, so it's significantly less polished than my more public-minded works, but I figure people may still get some use out of it. This upload consists of:
A TES5Edit script that can export all heightmap data for selected cells.
A web page (though it should run locally on your hard drive) that can load that dataset, process it, and generate a heightmap image (that you can right-click and save).
Caveats
This is one of my personal tools and as such, it is provided as-is. I may fix bugs or provide support on request, but in general I'm going to be a lot less keen on fixing this thing than I would be for my public works.
These tools were created specifically for Skyrim Classic, and are not guaranteed to work on Fallout 4 or Skyrim Special.
The web page tool was developed for Firefox and has only been tested in that browser. I can't guarantee stable or accurate behavior on other browsers.
There are two kinds of heightmap data for cells -- Vertex Height, embedded in Landscape data, and Max Height Data -- and the latter has not been fully decoded. When VHGT data is not available for a cell, MHDT is used as a fallback, which can affect the final results for the entire heightmap as brightness is normalized across the entire heightmap.