Opened 16 years ago
Closed 16 years ago
#2348 closed defect (fixed)
Cannot open a USGS DEM file?
Reported by: | dmalav | Owned by: | warmerdam |
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Priority: | high | Milestone: | 1.5.2 |
Component: | GDAL_Raster | Version: | 1.5.1 |
Severity: | blocker | Keywords: | usgsdem |
Cc: |
Description
Hi,
I could not open this USGS DEM file using GDAL. I checked the file with other dem viewing programs and it looks fine there.
I am using the following code.
GDALAllRegister();
poDataset = (GDALDataset *) GDALOpen( DemFile, GA_ReadOnly ); if( poDataset == NULL ) {
acad_printf("Error opening file %s\n%s\n",DemFile, CPLGetLastErrorMsg()); CPLFreeConfig(); return 0;
}
It comes with an error "not recognised as a supported file format."
File is attached, if you do not see the file please let me know. Any help would be greatly appreciated. Thanks, Dinesh
Attachments (1)
Change History (2)
by , 16 years ago
Attachment: | 39079G6.zip added |
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comment:1 by , 16 years ago
Keywords: | usgsdem added |
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Resolution: | → fixed |
Status: | new → closed |
I have come to the conclusion that the file is non-standard in at least a couple ways.
- At byte 150 it uses code " 4" for the "code defining elevation pattern" field instead of the usual " 1".
- The first B record has a column number of 0 instead of 1.
I reviewed the latest version of the sdts2dem program used to generate the file, and I don't see how it could have produced the indicated elevation pattern value. So that's sort of weird. Perhaps because it was generated with an older version?
In any event, I have modified usgsdemdataset.cpp to ignore these two quirks and then reading seems to work fine. Changes are in trunk (r14380) and 1.5 (r14381).
USGS DEM File