<div dir="ltr">Yes, ESRI does seem to have their own way of doing things, so it's not too surprising. <div><br></div><div>What's strange is that an ESRI-generated .prj file for EPSG:3857 looks something like this (no mention of the semi-minor axis):</div>
<div><br></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><div>PROJCS["WGS_1984_Web_Mercator_Auxiliary_Sphere",</div></div><div><div><span class="" style="white-space:pre"> </span>GEOGCS["GCS_WGS_1984",</div>
</div><div><div><span class="" style="white-space:pre"> </span>DATUM["D_WGS_1984",</div></div><div><div><span class="" style="white-space:pre"> </span>SPHEROID["WGS_1984",6378137.0,298.257223563]</div>
</div><div><div><span class="" style="white-space:pre"> </span>],</div></div><div><div><span class="" style="white-space:pre"> </span>PRIMEM["Greenwich",0.0],</div></div><div><div><span class="" style="white-space:pre"> </span>UNIT["Degree",0.0174532925199433]</div>
</div><div><div><span class="" style="white-space:pre"> </span>],</div></div><div><div><span class="" style="white-space:pre"> </span>PROJECTION["Mercator_Auxiliary_Sphere"],</div></div><div><div><span class="" style="white-space:pre"> </span>PARAMETER["False_Easting",0.0],</div>
</div><div><div><span class="" style="white-space:pre"> </span>PARAMETER["False_Northing",0.0],</div></div><div><div><span class="" style="white-space:pre"> </span>PARAMETER["Central_Meridian",0.0],</div>
</div><div><div><span class="" style="white-space:pre"> </span>PARAMETER["Standard_Parallel_1",0.0],</div></div><div><div><span class="" style="white-space:pre"> </span>PARAMETER["Auxiliary_Sphere_Type",0.0],</div>
</div><div><div><span class="" style="white-space:pre"> </span>UNIT["Meter",1.0],</div><div><span style="white-space:pre"> </span>AUTHORITY["EPSG",3857]</div></div><div><div>]</div></div></blockquote><div>
<br></div><div><br></div><div>But in the ArcGIS GUI, the details of the projection are reported as the following, with the modified semi-minor axis (this is what I used to modify the proj4 string in my WKT):</div><div><br>
</div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><div>WGS_1984_Web_Mercator_Auxiliary_Sphere</div></div><div><div>WKID: 3857 Authority: EPSG</div></div><div><div><br></div></div><div><div>Projection: Mercator_Auxiliary_Sphere</div>
</div><div><div>False_Easting: 0.0</div></div><div><div>False_Northing: 0.0</div></div><div><div>Central_Meridian: 0.0</div></div><div><div>Standard_Parallel_1: 0.0</div></div><div><div>Auxiliary_Sphere_Type: 0.0</div></div>
<div><div>Linear Unit: Meter (1.0)</div></div><div><div><br></div></div><div><div>Geographic Coordinate System: GCS_WGS_1984</div></div><div><div>Angular Unit: Degree (0.0174532925199433)</div></div><div><div>Prime Meridian: Greenwich (0.0)</div>
</div><div><div>Datum: D_WGS_1984</div></div><div><div> Spheroid: WGS_1984</div></div><div><div> Semimajor Axis: 6378137.0</div></div><div><div> Semiminor Axis: 6356752.314245179</div></div><div><div> Inverse Flattening: 298.257223563</div>
</div></blockquote><div><div><div><br></div><div><div class="gmail_extra">Jason<br>
<br><br><div class="gmail_quote">On Wed, Jan 22, 2014 at 4:18 PM, Even Rouault <span dir="ltr"><<a href="mailto:even.rouault@mines-paris.org" target="_blank">even.rouault@mines-paris.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Le mercredi 22 janvier 2014 22:09:33, Jason Greenlaw - NOAA Affiliate a écrit :<br>
<div class="im">> Even,<br>
><br>
> Thank you for catching the quote problem. I've fixed my WKT accordingly.<br>
><br>
> Unfortunately altering the SRS to GDAL's default EPSG:3857 definition<br>
> results in the same alignment problem when viewed in ArcGIS Desktop/Server,<br>
> so I altered it back to my custom WKT (using double quotes this time) - now<br>
> it's aligning properly again, but I'm still seeing the same error:<br>
><br>
> ERROR 6: No translation for Mercator_Auxiliary_Sphere to PROJ.4 format<br>
> is known.<br>
<br>
</div>Yes, this is an issue. Nobody agrees on how to represent WebMercator in WKT.<br>
There's a ticket pending in Trac about that.<br>
<br>
While looking at the .prj, I see a difference in the EXTENSION["PROJ4" node<br>
w.r.t what GDAL does.<br>
<br>
The .prj has :<br>
<div class="im">"+proj=merc +a=6378137 +b=6356752.314245179 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0<br>
+y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"<br>
<br>
</div>Whereas gdalsrsinfo EPSG:3857 shows :<br>
"+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0<br>
<div class="im">+k=1.0 +units=m +nadgrids=@null +wktext +no_defs"<br>
<br>
</div>So the ESRI stuff uses a non-spheric ellipsoid, which I believe is wrong...<br>
<br>
You can probably get the same result as ESRI by using the "+proj=merc<br>
<div class="im">+a=6378137 +b=6356752.314245179 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0<br>
</div>+k=1.0 +units=m +nadgrids=@null +wktext +no_defs" as -a_srs value.<br>
<div class="im"><br>
<br>
><br>
> It still produces valid output with 1.10.0, but with 1.10.1 it still exits<br>
> prematurely with status 1 and produces an all-zero image.<br>
><br>
> It seems that something was changed between 1.10.0 and 1.10.1 that made<br>
> this a fatal error.<br>
<br>
</div>I don't see anything obvious in the log that explain the behavioural change,<br>
but erroring out make sense when there's an error... So 1.10.1 behaviour seems<br>
OK.<br>
<div class=""><div class="h5"><br>
><br>
> Thanks,<br>
> Jason<br>
><br>
><br>
> On Wed, Jan 22, 2014 at 3:07 PM, Even Rouault<br>
><br>
> <<a href="mailto:even.rouault@mines-paris.org">even.rouault@mines-paris.org</a>>wrote:<br>
> > Le mercredi 22 janvier 2014 20:27:19, Jason Greenlaw - NOAA Affiliate a<br>
> ><br>
> > écrit :<br>
> > > When attempting to use a polygon shapefile (in custom web mercator<br>
> > > projection) with the gdalwarp cutline operation, operating on a GeoTIFF<br>
> > > (with same projection), the following error is output in both versions<br>
> > ><br>
> > > 1.10.0 and 1.10.1:<br>
> > > ERROR 6: No translation for 'Mercator_Auxiliary_Sphere' to PROJ.4<br>
> > ><br>
> > > format is known.<br>
> ><br>
> > The issue is that esri-3857.prf contains single quote characters instead<br>
> > of double quotes, and oceans_glakes_50m_3857.prj contain single quotes<br>
> > inside double quotes. Both are not valid AFAIK<br>
> ><br>
> > You should be able to overcome this with :<br>
> ><br>
> > ogr2ogr -a_srs EPSG:3857 oceans_glakes_50m_3857.shp<br>
> > oceans_glakes_50m_3857_fixed.shp<br>
> ><br>
> > and<br>
> ><br>
> > gdalwarp -s_srs EPSG:4326 -t_srs EPSG:3857 -r bilinear -srcnodata<br>
> ><br>
> > 9999.0 -dstnodata 9999.0 -tr 4000 9000 -overwrite -co COMPRESS=LZW -co<br>
> ><br>
> > TILED=yes sst.flt sst_projected.tif<br>
> ><br>
> > > With GDAL 1.10.0, the operation still completes successfully with a<br>
> > > zero exit status, but with GDAL 1.10.1 the operation fails with a<br>
> > > nonzero exit status, and the resulting GeoTIFF has zeros for all<br>
> > > pixels.<br>
> > ><br>
> > > Here is the command I'm using:<br>
> > > gdalwarp -co COMPRESS=LZW -cutline oceans_glakes_50m_3857.shp<br>
> > ><br>
> > > -srcnodata 9999.0 -dstnodata 9999.0 -overwrite sst_global.tif<br>
> > > sst_global_cut.tif<br>
> > ><br>
> > ><br>
> > > The input shapefile was produced by reprojecting with ogr2ogr from<br>
> > > EPSG:4326 to my custom projection (WKT is included below), which is<br>
> ><br>
> > stored<br>
> ><br>
> > > in a *.prf file. The source GeoTIFF is single-band with Float32 pixel<br>
> > > type.<br>
> ><br>
> > > The custom WKT can be found here:<br>
> > <a href="http://jgreenlaw.org/gdal/esri-3857.prf" target="_blank">http://jgreenlaw.org/gdal/esri-3857.prf</a><br>
> ><br>
> > > The cutline shapefile can be downloaded at:<br>
> > > <a href="http://jgreenlaw.org/gdal/oceans_glakes_50m_3857.tar.gz" target="_blank">http://jgreenlaw.org/gdal/oceans_glakes_50m_3857.tar.gz</a> (900kb)<br>
> > ><br>
> > > The source GeoTIFF can be generated from this FLT/HDR raster:<br>
> > > <a href="http://jgreenlaw.org/gdal/sst_flt.tar.gz" target="_blank">http://jgreenlaw.org/gdal/sst_flt.tar.gz</a> (11mb) by running these<br>
> ><br>
> > commands:<br>
> > > gdalwarp -s_srs EPSG:4326 -t_srs esri-3857.prf -r bilinear<br>
> > > -srcnodata<br>
> > ><br>
> > > 9999.0 -dstnodata 9999.0 -tr 4000 9000 -overwrite -co COMPRESS=LZW -co<br>
> > > TILED=yes sst.flt sst_projected.tif<br>
> > ><br>
> > > gdalwarp -co COMPRESS=LZW -te -20037507.0671618 -19971868.8804086<br>
> > ><br>
> > > 20037507.0671618 19971868.8804086 -srcnodata 9999.0 -dstnodata 9999.0<br>
> > > -tr 4000 9000 sst_projected.tif sst_global.tif<br>
> > ><br>
> > > Does anyone know if this behavior is to be expected when the above<br>
> > > error<br>
> ><br>
> > is<br>
> ><br>
> > > output? Is there a better method for reprojecting to Web Mercator that<br>
> > > will align properly in ArcGIS?<br>
> > ><br>
> > > Thanks<br>
> > > -Jason<br>
> > ><br>
> > ><br>
> > > Background:<br>
> > > The reason for using custom WKT for reprojecting to Web Mercator is<br>
> ><br>
> > because<br>
> ><br>
> > > I have experienced alignment problems displaying GDAL-produced GeoTIFFs<br>
> ><br>
> > in<br>
> ><br>
> > > ArcGIS when reprojecting using "EPSG:3857" as the target SRS (this<br>
> > > seems<br>
> ><br>
> > to<br>
> ><br>
> > > be related to <a href="http://trac.osgeo.org/gdal/ticket/3962" target="_blank">http://trac.osgeo.org/gdal/ticket/3962</a>).<br>
> > ><br>
> > > I generated the WKT below by copying the 102113 definition in<br>
> > > $GDAL_DATA/esri_extra.wkt and merging information from an ESRI Web<br>
> ><br>
> > Mercator<br>
> ><br>
> > > *.prj file. Using this custom WKT as the target SRS with gdalwarp<br>
> ><br>
> > normally<br>
> ><br>
> > > results in rasters that align properly with ArcGIS Web Mercator data<br>
> > > (without on-the-fly datum transformation).<br>
> ><br>
> > -------------------------------------------------------------------------<br>
> > --<br>
> ><br>
> > > ------------------- Custom WKT for reprojecting to ESRI Web Mercator<br>
> ><br>
> > using<br>
> ><br>
> > > GDAL (<br>
> ><br>
> > > <a href="http://jgreenlaw.org/gdal/esri-3857.prf" target="_blank">http://jgreenlaw.org/gdal/esri-3857.prf</a>):<br>
> > -------------------------------------------------------------------------<br>
> > --<br>
> ><br>
> > > -------------------<br>
> > ><br>
> > > PROJCS['WGS_1984_Web_Mercator_Auxiliary_Sphere',<br>
> > ><br>
> > > GEOGCS['GCS_WGS_1984',<br>
> > ><br>
> > > DATUM['D_WGS_1984',<br>
> > ><br>
> > > SPHEROID['WGS_1984',6378137.0,298.257223563]<br>
> > ><br>
> > > ],<br>
> > > PRIMEM['Greenwich',0.0],<br>
> > > UNIT['Degree',0.0174532925199433]<br>
> > ><br>
> > > ],<br>
> > > PROJECTION['Mercator_Auxiliary_Sphere'],<br>
> > > PARAMETER['False_Easting',0.0],<br>
> > > PARAMETER['False_Northing',0.0],<br>
> > > PARAMETER['Central_Meridian',0.0],<br>
> > > PARAMETER['latitude_of_origin',0.0],<br>
> > > PARAMETER['Standard_Parallel_1',0.0],<br>
> > > PARAMETER['Auxiliary_Sphere_Type',0.0],<br>
> > > UNIT['Meter',1.0],<br>
> > > EXTENSION["PROJ4",<br>
> > ><br>
> > > "+proj=merc +a=6378137 +b=6356752.314245179 +lat_ts=0.0<br>
> ><br>
> > +lon_0=0.0<br>
> ><br>
> > > +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"<br>
> > ><br>
> > > ],<br>
> > > AUTHORITY["EPSG","3857"]<br>
> > ><br>
> > > ]<br>
> ><br>
> > --<br>
> > Geospatial professional services<br>
> > <a href="http://even.rouault.free.fr/services.html" target="_blank">http://even.rouault.free.fr/services.html</a><br>
<br>
--<br>
Geospatial professional services<br>
<a href="http://even.rouault.free.fr/services.html" target="_blank">http://even.rouault.free.fr/services.html</a><br>
</div></div></blockquote></div><br></div></div></div></div></div>