I have about 1,000 rasters which are around 10km x 10km and partially overlap to cover a whole country.
I would like to convert these into a single national raster, and where raster overlap, add the cell values together.
Currently, I am using ArcGIS's workspace to new raster tool, but I would like to replicate the process in the R language.
I've tried a couple of things but usually end up with only the intersection of the rasters. Many of the solutions on StackExchange advocate cropping to a common area, which is the exact opposite of what I want.
IS there a general solution for aligning two rasters and then making a mosaic which has the combined extent of both rasters?
Can this method be scaled to work for thousands of rasters?
> sessionInfo() R version 3.3.2 (2016-10-31) Platform: x86_64-w64-mingw32/x64 (64-bit) Running under: Windows 7 x64 (build 7601) Service Pack 1 locale:  LC_COLLATE=English_United Kingdom.1252 LC_CTYPE=English_United Kingdom.1252 LC_MONETARY=English_United Kingdom.1252  LC_NUMERIC=C LC_TIME=English_United Kingdom.1252 attached base packages:  stats graphics grDevices utils datasets methods base other attached packages:  rgdal_1.2-5 raster_2.5-8 sp_1.2-4 loaded via a namespace (and not attached):  tools_3.3.2 Rcpp_0.12.9 grid_3.3.2 lattice_0.20-34 > rasterOptions() format : raster datatype : FLT8S overwrite : FALSE progress : none timer : FALSE chunksize : 1e+07 maxmemory : 1e+08 tmpdir : D:/RTemp\RtmpgzISfL/raster/ tmptime : 168 setfileext : TRUE tolerance : 0.5 standardnames : TRUE warn depracat.: TRUE header : none