Different origin problem while merging rasters

Question

I have two dem files downloaded via the getData function in the raster package. Here you can see the code:

I tried to make the example reproducible so there you have it.

library(raster)
dem_n1<-getData("SRTM",lon=26,lat=43)
dem_n2<-getData("SRTM",lon=31,lat=43)
demALL<-merge(dem_n1,dem_n2)

While attempting to perform the merge, the following error appears:

Error in compareRaster(x, extent = FALSE, rowcol = FALSE, orig = TRUE,  : 
  different origin

Answer 1

This works as expected for me:

> demALL
class       : RasterLayer 
dimensions  : 6000, 12000, 7.2e+07  (nrow, ncol, ncell)
resolution  : 0.0008333333, 0.0008333333  (x, y)
extent      : 25, 35, 40, 45  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0 
data source : c:\Temp\R_raster_rhijmans\r_tmp_2015-10-22_102651_340_06019.grd 
names       : layer 
values      : -37, 2573  (min, max)

However, there is a small difference in the origin due to floating-point imprecision

 origin(dem_n1)
 #[1] 0 0
 origin(dem_n2)
 #[1] -3.552714e-15  0.000000e+00

but that should not matter

So I wonder if you are using the current versions of R and raster? If you are, you could probably get around this by setting

 rasterOptions(tolerance = 0.1)

(That is actually the default value) or perhaps

.Machine$double.eps <- 0.000000001

or something like that

Answer 2

I faced a similar issue with other raster files even when using the most recent version of R and the raster package. The above did not work for me. Instead, by trying

mergedraster <- raster::merge(raster1, raster2, tolerance = 0.1)

worked fine.