id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc 6863,gdalwarp gives incorrect result going from utm to epsg:3857,jessecrocker,warmerdam,"gdalwarp output when going from `+proj=utm +zone=12 +ellps=clrk66 +units=m +no_defs` to epsg:3857 is incorrect, it appears to be off by the offset between nad27 and wgs84. Going from `+proj=utm +zone=12 +ellps=clrk66 +units=m +no_defs` to epsg:4267, then from epsg:4267 to epsg:3857 does give correct results. gdalsrsinfo output for the file i am working with {{{ PROJ.4 : '+proj=utm +zone=12 +ellps=clrk66 +units=m +no_defs ' OGC WKT : PROJCS[""NAD_1927_UTM_Zone_12N"", GEOGCS[""GCS_North_American_1927"", DATUM[""D_North_American_1927"", SPHEROID[""Clarke_1866"",6378206.4,294.9786982138982]], PRIMEM[""Greenwich"",0], UNIT[""degree"",0.0174532925199433]], PROJECTION[""Transverse_Mercator""], PARAMETER[""latitude_of_origin"",0], PARAMETER[""central_meridian"",-111], PARAMETER[""scale_factor"",0.9996], PARAMETER[""false_easting"",500000], PARAMETER[""false_northing"",0], UNIT[""metre"",1, AUTHORITY[""EPSG"",""9001""]]] }}} Command that gives incorrect output: ` gdalwarp -t_srs epsg:3857 source.tiff source-3857.tiff` But this does work correctly: ` gdalwarp -t_srs epsg:4267 source.tiff source-4267.tiff; gdalwarp -t_srs epsg:3857 source-4267.tiff source-3857-from-4267.tiff` I have attached 2 files, one is the `source.tiff` file from my test case, the other is the incorrect result layered over the source file with 50% opacity in qgis to show the shift.",defect,closed,normal,2.1.4,default,2.1.3,normal,fixed,,