The output I get from QGIS 7.0.1 for an ASCII DEM file doesn't seem to be a correct format. It differs from the format I get when I download a DEM file from webGIS ( http://www.webgis.com/terr_us75m.html) .

I have an application that will accept an ASCII DEM file as input. When I input the DEM file created by QGIS it says the format is invalid. When I input the DEM file I downloaded from webGIS is fine.

The start of the QGIS DEM file looks like this:

         gmted_mea075_Contour-02.dem                                                                     -1223458.8333  4712 3.7222

The start of the downloaded DEM file looks like this:

SPANAWAY, WA-24000 LAT:: 47 0 0.0000 N LONG:: -122 22 30.0000 W SCALE:: 24000 (C) www.webmet.com

Has there been a change in the ASCII DEM format?

My input application is from 2003.

I create the DEM file: Raster > Analysis > DEM (Terrain models) For the file type I select: USGS Optional ASCII DEM(*.dem *,DEM)

closed as off-topic by PolyGeo Aug 19 '17 at 19:38

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  • What does the header look like? Open with NotePad++ (or other good text editor)... What does GDALinfo say (gdal.org/gdalinfo.html)? please edit this into your question. I'd say your driver USGS DEM isn't right but there's a few that have .dem extension (eg Golden Surfer DEM, Esri ASCII sometimes..) STDS DEM docs are mcmcweb.er.usgs.gov/sdts and see gis.stackexchange.com/questions/70607/… – Michael Stimson Jul 16 '15 at 0:26
  • I'm not sure how long the header is supposed to be but the first 135 characters are posted above under QGIS DEM. I'm going to investigate the QDAL programs and see what I can find out. -Thanks – Moralez Jul 16 '15 at 18:03
  • The GDAL driver page gdal.org/frmt_usgsdem.html is listing quite a many options. If QGIS is missing those selections in the user interface I believe you must experiment with ogr2ogr and try to find correct switches. Once you have found them you can edit the gdal_translate command in the export window of QGIS and add the right parameters. – user30184 Jul 16 '15 at 19:30
  • GDALinfo c:\your\path\gmted_mea075_Contour-02.dem will give you the driver name on the first line, this will be the same driver needed by QGIS to open the file. If GDALinfo can't find it then resort to the header, it's usually pretty obvious where the header ends and the data begins but you will need to use a good text editor that wont try to load the whole file into memory to open it. – Michael Stimson Jul 16 '15 at 21:50
  • Thanks all for your assistance. There doesn't seem to be a way to do what I want to do. I'm completely new to GIS so my knowledge is greatly limited. QGIS seems to be a nice product but it's conversions abilities with DEMs are lacking, IMO. I'm going to continue trying different options and looking for free software to see if I can accomplish my tasks. Thanks for your help. – Moralez Jul 17 '15 at 20:49

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