Just making sure the list is covered as well... ---------- Forwarded message ---------- From: Jared Carlson <[email protected]> Date: Mon, Nov 23, 2009 at 4:15 PM Subject: Re: [gdal-dev] Help with USGS SDTS DEM To: Greg Coats <[email protected]>
Hi Greg, Ok, but then where does the min,max calculation give me a different answer? The ComputeRasterMinMax gives me (0,4116) but as I said, doing the "dumb" loop gives me 4338 which is consistent with the conversion... Any ideas?? Thanks a lot for the help though, I appreciate any boost of confidence, even simple unit conversions... - Jared On Mon, Nov 23, 2009 at 4:10 PM, Greg Coats <[email protected]> wrote: > 4338 feet = 1322 meters > Greg > > On Nov 23, 2009, at 3:53 PM, Jared Carlson wrote: > > Hello, > > I'm trying to reconcile some geological data, via a SDTS DEM, and comparing > the elevations from what I'm reading in GDAL to what I'm seeing in ENVI. I > seem to be reading everything in but am having issues with the actual > elevation data which seems to be scaled incorrectly. > > For example, moving through the ENVI image, I see the maximum value for a > Maui DEM is 1322, but the Min/Max from GDALComputeRasterMinMax( .. ) is 0, > 4116, but when I loop through my raster data, using: > > pafScanline = (float*) CPLMalloc( sizeof(float) * nXSize * nYSize ); > /* Read the buffer via the following call RasterIO( > GF_Read/GF_Write, xoffset, yoffset, width, height, void * data, > xBufWidth, yBufHeight, Type, pspace, lspace > ) > */ > poBand->RasterIO( GF_Read, 0, 0, nXSize, nYSize, pafScanline, nXSize, > nYSize, GDT_Float32, 0, 0 ); > > for (int i=0; i<nXSize*nYSize; i++) > { > if ( pafScanline[i] > value ) value = pafScanline[i]; > } > > I see a max value of 4338... > > Does anyone have some experience with this?? I'm a newbie to GDAL so > perhaps I'm doing something wrong. I know the actual data in the rasterBand > is an int, but it says in the doc that RasterIO should still grab the > correct data values, and when looking at the GetDataNoValue that seems to > indicate that I did read in the data correctly but the maximums seem off, > and ENVI has different data values. I checked the Scale and Offset, which > are 1.0, and 0.0 respectively. > > Thanks for any help, > > - Jared > > >
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