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I've produced a set of topographic derivatives using both SAGA and ArcGIS. They are all in the same CRS.

When I load them into R, however, the proj4 strings are different:

>arcRaster
class      : RasterLayer 
dimensions : 16002, 21200, 339242400  (nrow, ncol, ncell)
resolution : 10, 10  (x, y)
extent     : 480200, 692200, 4896280, 5056300  (xmin, xmax, ymin, ymax)
crs        : +proj=utm +zone=11 +datum=NAD83 +units=m +no_defs +ellps=GRS80 +towgs84=0,0,0 
> sagaRaster
class      : RasterLayer 
dimensions : 16002, 21200, 339242400  (nrow, ncol, ncell)
resolution : 10, 10  (x, y)
extent     : 480200, 692200, 4896280, 5056300  (xmin, xmax, ymin, ymax)
crs        : +proj=utm +zone=11 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs 

Note the raster produced in saga is missing +datum=NAD83. They align properly and they stack without problems. Why is the datum information missing?

  • try to reproject data. – Muhammad Imran Siddique Mar 11 at 23:50
  • It doesn't need to be reprojected - I know they are in the same projection, it's just that there is an inconsistentcy in the proj4 string – Nick Mar 12 at 14:37
  • For example if I open both layers in ArcMap it recognizes the projections to be the same "NAD_1983_UTM_Zone_11N". It is only when loaded into R that the projections appear different. Furthermore, if i simply do crs(sagaRaster) <- crs(arcRaster) or vis versa they still align perfectly and stack. I would expect that if they were in fact different projections, simply redefining the CRS like this would cause some offset. – Nick Mar 12 at 15:35
  • check the matadata comparison gdalinfo filename – Muhammad Imran Siddique Mar 13 at 7:49
  • The datum information is there when i look with gdal info (also appear as identical coordinate system in arcmap) – Nick Mar 13 at 22:23

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