Problems Exporting DEM

Mike TrulyMike Truly Global Mapper UserPosts: 42Trusted User
edited March 2010 in Technical Support
I am using a older version of GM 10.02 (and wondering if this problem is perhaps fixed in the latest version) and trying to export a DEM.

The dataset is fine within GM but when I go to export the DEM to some specific bounds and I want to set the sample spacing to some custom sizes with no gridding, I get some sort of corrupt file that won't import into my other app.

For example, if I set the sample spacing to 500ft, square cells, fill gaps, it writes the file but won't import into my app. But If I use the same settings and choose 2x2 gridding, those DEMs will import just fine. The resulting DEMs (whether a single or gridded) are tiny in filesize so this is not the issue.

If I try to change the sample spacing to 1000, gridded... this file is corrupt and won't import. So it seems like certain settings/sizes make it happy and others don't.

Were there any issues like this with this, older version?

Thanks!

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Mike,

    Are you perhaps setting up some setting on the Gridding tab to split your export? If so, could you be specific as to which settings are failing, there could be a clue there. Also if you could post one of the files that your other application thinks is corrupt that would be useful. Can Global Mapper read in the corrupt files?

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    Mike,

    Thanks for the response. Attached is a zipfile with 4 small DEMs that were generated by using the standard 2x2 gridding. Two of the files will import into my app (3dsMax2010_64) and the other two say 'improper file format' when trying to import.

    the A1,B1 file works... the A2,B2 doesn't.

    GM will open the problem DEMs, but the app wont.

    Thanks again.
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    And here's an unsplit file with the same 800x800 cell size which throws the same error when trying to import into my app.

    Thanks!
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    OK, I just fired up my older GM9 and loaded the same workspace and successfully exported an unsplit DEM using the same 800x800 cell size and it imports fine into my app. Haven't tried the split version yet.

    It appears to be something particular to GM10. So I can work around the problem for now.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Mike,

    Can you provide the DEM created by v9 that works in your other software? I can't see any changes that were made between v9 and v11 that would affect DEM export.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    Attached is the DEM from GM9 that works without complaint.

    Thanks!
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Mike,

    Thanks for the file. I did a difference of the two files, but since they cover slightly different areas every line was different except for the first one, so it was hard to spot what has changed. Was the export done with different options in v9 than in v11? Is it possible for you to provide the v11 file to your other software vendor to see why they can't read it?

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    Mike,

    The GM version that I was trying to use to generate the DEM originally was GM 10.02... I haven't upgraded to v11 yet. As far as I know, the GM9 settings were the same as used in GM10 (I will take another look to make sure). Unfortunately, Autodesk is not going to provide any support as the DEM importer is a minor aspect to their software.

    In any event, I have worked around the issue for now.

    Thanks again.
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    This is still driving me bonko.

    Now the problem is exhibiting itself in GM9 as well as GM10. (And it does it in MAX2010_64 as well as the older MAX2008_32... I'm sure the importer software is the same in both versions).

    When you choose to setup a gridded export 2x2 in GM, the result is that you get 4 files... A1, A2, B1, B2 or 1,2,3,4. On each try, 2 of the pieces will import successfully and 2 will not. Something has to be different about 2 of the pieces since the other 2 import fine.

    Doesn't seem to matter if the cell size is small or large resulting in small or large filesizes as it will do it on either.

    Weird.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Mike,

    Unfortunately a lot of software doesn't really comply to the DEM specification but will fail on a subset of DEMs if anything is not setup exactly how that software expects it. This means that a lot of perfectly valid DEM files will not load in some software. Unless you can get support from that software vendor I'm not sure what else I can do. There is probably only a particular set of sizes or some criteria that the other software supports, but you'd have to know what those limitations were.

    Can you try exporting to maybe a 3D DXF Mesh and see if that can load into the software?

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    I understand Mike. But since your product writes 4 files and two of them are readable and two are not and you have the ability to inspect the files for differences, I am just letting you know the status of this issue.

    Autodesk provides no support for their products. The DEM importer was written years ago, is about 1/1000th of the total app of MAX and Autodesk deemed it perfect and of course provides no details about it's inner workings, likes/dislikes, etc. The DEM importer works great... when it works. And it has worked many times in the past. But something is not working now and I can't find the magic settings to make it work reliably now... which is aggravating. There are other DEM importers for MAX but this DEM importer (the Autodesk DEM importer) normally actually brings in the mesh at the proper scale... which is a huge benefit to me since I don't then have to deal with trying to re-scale and get it at the precise right size.

    I am currently trying to import a DXF from GM10 but it is taking forever and the MAX DXF importer presents confusing menus upon import which I don't care about. The DEM importer presents nothing and imports a mesh in short order... that's why I use it. All I want is the mesh... preferrably at the right size.

    The DXF importer is still trying to import and is acting hung. Will try some more formats to import.

    Thanks! (I'm not trying to be sarcastic... I mean it!).
  • Frank2Frank2 Super Moderator Posts: 105
    edited March 2010
    You may want to bring up the issue on their forum.
    http://area.autodesk.com/forum/autodesk-3ds-max/
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    OK, for this project... I may have found something that will work.

    To summarize... it seems that when I export the full terrain (no gridding), MAX will read the file in. Let's say I export the terrain in 3 cell sizes... 300x300, 150x150 and 75x75. MAX will successfully read in the 300x300 and 150x150 cell sizes. The 75x75 cell size will be read in but the resulting mesh is not complete therefore useless. (Since my goal is to build a multi-rez terrain by blending the three resolutions together into one mesh... this is useless to me).

    When I try to export gridded at 2x2 (or 3x3... so I assume other multiples too) I get multiple files and MAX will successfully read half the files and the other half it won't. Also if I watch the progress bar in GM as it makes the DEMs, I can see a speed difference as they are being made. Some of the gridded files show the progress bar at a steady rate throughout. Others of the gridded files show the progress bar zip through half the export and then slow down for the other half... or zip through the whole thing. This makes me think that something imay be fishy in the way they are written. But looking at the resulting filesizes... they all look legit and are of a similar size.

    Anyway, what worked this time is to write out full terrains (no gridding) at resolutions of 100x100, 200x200 and 400x400.

    The original dataset in GM is a merge of a 1 arcsec and a 1/3 arcsec. Not sure what this all means but I can proceed with my project for the moment.

    Thanks!
  • disneytoydisneytoy Global Mapper User Posts: 1
    edited March 2010
    I could use some advice on a similar matter. I have a DEM (25MB, .tif, 3601x3601, 16 bit, SILC TIFF) of North Korea I need to import into 3DS max 2010,to do an animation for a documentary on the 60th anniversary of the War. It appears to be 55 miles by 55 miles.

    other than cropping it down to the "battle Field area" What is the workflow to use to, crop, export (best format), and import into 3ds max?

    From Mike's posts, I see I need a specific DEM importer for Max. But are other output formats desirable?

    Thanks

    Max Webber

    More details: The File is: ASTER Global Digital Elevation Model - GDEM, 1 Archsec.
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    Max,

    The built-in DEM importer is the best (for my needs, anyway) when it works. It will bring in the terrain at the right scale but be WAY off in space... you will have to move it to 0,0,0 to work with it.

    Just go to File>Import>DEM (or Land XML or something... can't remember the verbage) and import. When the menu that pops up shows a number of surfaces... it will give you a mesh. If it shows 0 surfaces, it will give you nothing. Sometimes, the menu will show a number of surfaces and it will give you a mesh... but it will be totally incomplete and unusable.

    When it works... it works great. Just have to play with the GM export settings until you get something that works.

    When it does come into MAX, select the mesh, set the properties to display as box (for speed) and then select all the edges of the mesh and set them to 'visible', then turn off display as box. This can take a while if the mesh is huge. Then you will be able to properly see the mesh in all views. The mesh is way off in space but the pivot is located at 0,0,0. Move the pivot to the mesh then move the whole thing back to 0,0,0.

    Good luck!
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Mike,

    The speed differences that you are seeing is likely caused by a slowdown when you hit an area of no data if you have the option checked to fill gaps in the data. With that checked you are doing a lot more work in no data areas as the surrounding area is checked for valid data that can be used to fill the gap. If you uncheck that option you should see consistent speed throughout.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Mike TrulyMike Truly Global Mapper User Posts: 42Trusted User
    edited March 2010
    Thanks for the explanation Mike. I do have that option checked... so that's probably it.

    When you say 'no data'... when I'm looking at the terrain as presented in GM10, it looks complete to me (there are no holes visible anywhere). Would I be seeing holes in the terrain in GM if there was no data in certain areas? Or is GM visually filling them in?

    Thanks again.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    Mike,

    GM won't fill in gaps during display, so if you aren't seeing any gaps there likely aren't any. However, if your export bounds go beyond the actual data area, then the samples outside of any data layers will still be checked to potentially filling gaps, but nothing will be found to fill a gap, slowing things down a bit.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
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