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i am working on a project which is not commercial and i need some digital elevation data for visualization. in net i have found a link and i have downloaded .asc data from following link..

SRTM Data Link

with arcmap in toolbox, Conversion Tools > To Raster > ASCII to Raster , with floating options i can convert it to what i want. but when i export it as tiff and taking info with gdalinfo i am getting no coordinate system information and three band (RGB)...

in normal dted2 file with gdalinfo i am getting this result with other coordinate info:

GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]

Pixel Size = (0.000277777777778,-0.000277777777778)

Image Structure Metadata:
  INTERLEAVE=BAND

Band 1 Block=3601x1 Type=Int16, ColorInterp=Gray
  NoData Value=-32767
  Unit Type: m

Can you help me how can i convert srtm asc data to dem or dted as below with arcmap or gdal? and is there any batch conversion for this?

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1 Answer 1

up vote 2 down vote accepted

I do it this way:

I download srtm data from : http://srtm.csi.cgiar.org/SELECTION/listImages.asp Also, I just checked, use ftp to download, its a lot faster than http.

Then load it in Global Mapper, re-project in to desired coordinate system and export as 32 bit floating point elevation data. (yes its that simple, 2 min job at max). I tried in ArcMap and did some google search, seems like ArcMap doesnt like DEMs very much.

If you dont have GlobalMapper, go for GRASS. There you have to read a few things to make what you want, but it will work I believe.

Cheers N

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Maybe FTP is preferred for various reasons (e.g., sometimes to "respect" bandwidth limits) but for me it was/is always the slowest path. –  Nikos Alexandris Nov 28 '13 at 2:40

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