Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

I have some survey data exported from Civil 3D in both dtm and dem formats. I thought the I would be able to use the dem more easily, but I think the format is different from a USGS DEM. Is it possible to use this data in either ArcMap or QGIS? I'm using QGIS for raster analysis with the GRASS plugin as I don't have the 3D Analyst extension.

Thanks for any help!


@johanvdw Thanks guys, here it is. Starts with 'Autodesk Export Surface2DEM' then

{1 2 405 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 0.000000000000000D+00 1 1 4 0.585166731876923D+07 0.212104288166666D+07 0.585166731876923D+07 0.212938888166666D+07 }

share|improve this question
1  
Try posting the first lines of the DEM file here, it will give an idea which procedure you can use to load the file. –  johanvdw Jan 17 '13 at 19:13
    
@johanvdw- I'm actually able to open the DEM in ArcMap, and have tried to convert it to a Geotiff to use in QGIS but that hasn't worked. I'm unable to open directly in QGIS. Sorry, I'm not sure how to post the lines, can you advise? –  Erin Jan 17 '13 at 20:03
2  
open the file with a text-editor such as notepad –  johanvdw Jan 17 '13 at 21:00
    
try to open with notepad or wordpad, and copy just a few of the top lines –  Brad Nesom Jan 17 '13 at 21:01
add comment

2 Answers

up vote 1 down vote accepted

In Civil3d (2010+), you can choose GeoTiff as an export option, then load into QGIS (1.8) as a regular old raster, create a hillshade etc.

They make you choose this in the 'Dem file name' option in the export surface dialog so it's not immediately obvious where to change formats.

enter image description here

enter image description here

share|improve this answer
    
@WolfOdrade- This is really useful, thanks. The file was exported by someone else so I'll see if they can send me a geotiff. –  Erin Jan 20 '13 at 7:22
add comment

In Autocad Civil there's no .DTM format, sir, only a .TIN one.

You can easily convert a C3D surface to Dem (readable by Qgis) by means of the _SurfaceExportToDem command.

:)

share|improve this answer
    
The file was exported by someone else for my use so I'm not sure what process they used. It just seemed that the DEM may need conversion or some processing as I was having trouble getting it to load or render. –  Erin Jan 20 '13 at 7:19
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.