Never mind! I just checked the histogram and the data is getting scaled,
I forgot that I was also scaling it in my mapfile so the results where
getting masked.
-Steve
On 1/23/2020 8:20 PM, Stephen Woodbridge wrote:
Hi all,
I'm having trouble getting my VRT file to scale the source data into
my ColorTable.
I've been looking at this https://gdal.org/drivers/raster/vrt.html
The source GeoTiff has:
Band 1 Block=4500x1 Type=Float32, ColorInterp=Gray
Minimum=1.082, Maximum=46.322, Mean=34.181, StdDev=2.049
NoData Value=-30000
Overviews: 2250x2126, 1125x1063, 563x532, 282x266, 141x133, 71x67
Metadata:
STATISTICS_MAXIMUM=46.321998596191
STATISTICS_MEAN=34.181107349018
STATISTICS_MINIMUM=1.0819988250732
STATISTICS_STDDEV=2.0492649377546
My goal is to scale the source 0-50 into 10-240 in the ColorTable.
The VRT looks like:
<VRTDataset rasterXSize="4500" rasterYSize="4251">
<GeoTransform> -180.0 ,0.08 , 0 , 90.0 , 0 , -0.04 </GeoTransform>
<Metadata>
</Metadata>
<VRTRasterBand dataType="Byte" band="1">
<ColorInterp>Palette</ColorInterp>
<ColorTable>
<Entry c1="0" c2="0" c3="0" c4="255"/>
<Entry c1="0" c2="0" c3="255" c4="255"/>
...
<Entry c1="255" c2="255" c3="255" c4="255"/>
</ColorTable>
<ComplexSource>
<SourceFilename
relativeToVRT="1">HYCOM_tomorrow_salinity_0.tif</SourceFilename>
<SourceBand>1</SourceBand>
<ScaleOffset>0</ScaleOffset>
<ScaleRatio>1</ScaleRatio>
<NODATA>0</NODATA>
<SrcRect xOff="0" yOff="0" xSize="4500" ySize="4251"/>
<DstRect xOff="0" yOff="0" xSize="4500" ySize="4251"/>
</ComplexSource>
</VRTRasterBand>
</VRTDataset>
50 - 0 = 50
240 - 10 = 230
230 / 50 = 4.6 = ScaleRatio
10 = ScaleRatio
I've tried a lot of other value trying to play with the scaling.
I also tried using:
<Exponent>0</Exponent>
<SrcMin>0</SrcMin>
<SrcMax>50</SrcMax>
<DstMin>10</DstMin>
<DstMax>240</DstMax> but that doesn't appear to work either. Using:
GDAL 2.2.3, released 2017/11/20 on Unbuntu 18.04 My conclusion is that
I'm not understanding the meaning of these fields or these are meant
for something other than my goal. Any help would be appreciated.
Thanks, -Steve
_______________________________________________
gdal-dev mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
