I'm having issues when projecting habitat suitability rasters (WGS84) to a projected coordinate system (Africa Albers Equal Area Conic). The reason I reproject the rasters is so that I can calculate the area of suitable habitat which is intended to be used for conservation-related purposes.
Considering that I have about 900 individual rasters that need to be reprojected for area calculation purposes I decided to automate the process in R. However, I realised that there is a difference in 'cell size' values for the same rasters between R and ArcMap 10.7.
For example, when I use 'Raster A' (cell size: X: 0.00833333376786619; Y:0.00833333376786619) and project it to Africa Albers Equal Area Conic the cell sizes are different between R and ArcMap and therefore also the area of suitable habitat...
After reprojecting in ArcMap the cell size of the rasters are X: 879.789038737608
But in R the 'cell size' is different: X: 853 Y: 902
The resampling method used was bilinear when reprojecting the raster.
This turned out to be a massive headache to me because I do not know which area calculated is the correct one as both R and ArcMap provide area estimates vastly different from one another. Area calculated from R = 18000km2 and in ArcMap 14000km2.