Also, look at the coverage area, DEMs will often (but not always) have a nice "round" coverage area such as 30 arcsecond, 3 arcsecond, or 1 arcsecond. The pixel values are often converted to a physical unit such as feet or meters so you can compare the values to height values in Google Earth or a similar tool. These heuristics tend to hold for pieces of larger terrain maps such as SRTM, GTOPO30, ASTER, etc. Small area terrain maps from stereo imagery, airborne SAR, LIDAR, etc. are less likely to hold to the coverage area rule but are probably still in physical units.
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Even Rouault Sent: Wednesday, May 02, 2012 3:25 AM To: weixj Cc: [email protected] Subject: Re: [gdal-dev] how to judge a file is a DEM file or not? Selon weixj <[email protected]>: > How to judge a file is a DEM file or not? There's no straightforward answer. Some formats (DTED, SRTM, ...) are specifically aimed for DEM. But DEM can also be conveyed through more generic purpose formats such as GeoTIFF. In that case, looking at the data type of the raster bands might give a clue. DEM use generally Int16 or Float32 data types (at least, not Byte which has not a sufficient range to express elevations). Eventually, looking at the associated metadata might be necessary to know the semantics of the data. Best regards, Even _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev This message and any enclosures are intended only for the addressee. Please notify the sender by email if you are not the intended recipient. If you are not the intended recipient, you may not use, copy, disclose, or distribute this message or its contents or enclosures to any other person and any such actions may be unlawful. Ball reserves the right to monitor and review all messages and enclosures sent to or from this email address. _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
