[Qgis-user] trying to convert geotiff UTM toWGS84

[Nicolas Cadieux]

Hi,
If you are using gdal translate with -a_srs "EPSG:4326", you are simply overwriting the CRS in the file. That is likely messing thing up as the file is not actually reprojected.  
Nicolas

> Le 18 juin 2018 à 03:40, Donald Harter <harterc2 at att.net> a écrit :
> 
> I started out trying to merge some geotiff topo maps of a state.  I kept
> getting results that were all black.  It seems that style was palletee
> unique values and that merge could not handle that.  So I converted them
> to multiband color using gdal_translate.  Some of the merged topos were
> not lining up next to each other as they should.  It seems that they
> were on the edge of a UTM region, each one in a different one.  So I
> decided to convert them to WGS84 latitude and longitude.  I can
> partially do that but when I display the files the coordinates seem to
> be in utm instead of latitude and longitude.
> Here is info on one such file:
> 
> Original
> out2
> Name
> out2
> Source
> /tmp/out2.tif
> Provider
> gdal
> CRS
> EPSG:4326 - WGS 84 - Geographic
> Extent
> 212740.2107839999953285,3630863.9934609998017550 :
> 413984.4187070000916719,3772545.1990390000864863
> Unit
> degrees
> Width
> 7923
> Height
> 5578
> Data type
> Byte - Eight bit unsigned integer
> GDAL Driver Description
> GTiff
> GDAL Driver Metadata
> GeoTIFF
> Dataset Description
> /tmp/out2.tif
> Compression
> 
> Band 1
> STATISTICS_MAXIMUM=255
> STATISTICS_MEAN=238.21578824081
> STATISTICS_MINIMUM=131
> STATISTICS_STDDEV=37.09178797644
> More information
> AREA_OR_POINT=Area
> TIFFTAG_DATETIME=1996:10:29 16:21:10
> TIFFTAG_IMAGEDESCRIPTION=USGS GeoTIFF DRG 1:250000 Quad of Tularosa.
> Product:487866
> TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
> TIFFTAG_SOFTWARE=USGS CD Archiver program tif2usgsdrg v.1.0
> TIFFTAG_XRESOLUTION=250
> TIFFTAG_YRESOLUTION=250
> Dimensions
> X: 7923 Y: 5578 Bands: 1
> Origin
> 212740,3.77255e+6
> Pixel Size
> 25.4,-25.4
> Its coordinates are EPSG:4326, but they display as UTM and not latitude
> and longitude.  It is as if the pixel data coordinates were not
> converted but everthing else one.  I have tried gdaltransform and
> gdal_translate.
> So how do I do this? Maybe I am forgetting a parameter.
> Here is what I ran on the command line after the gui did not work:
> 
> gdal_translate -a_nodata 0.0 -ot Byte -a_srs "EPSG:4326" -expand rgba
> -of GTiff /srv/data/nm_topo/scale_250k/c33106a1.tif /tmp/out2.tif
> 
> gdalwarp  -ot Byte -s_srs "EPSG:4267" -t_srs "EPSG:4326"  -of GTiff
> /srv/data/nm_topo/scale_250k/c33106a1.tif /tmp/out2.tif
> 
> I am using the latest version of qgis.  If I try to use -expand in the
> processing gui for translate it says that it is an invalid parameter.
> It works on the command line though.
> 
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