Just looking for some general advice here.
I’m working with Landsat 5, 7 and 8 imagery doing NDVI trend analysis. Currently, I’m trying to mosaic scenes by year but running into a serious memory barrier. I have a 64-bit Windows machine but unfortunately I’m confined to 8 GB of RAM. When I try to mosaic even two scenes I run into a “Cannot allocate vector of __GB” error. I understand that I can get around this error by changing the ‘chunksize’ and ‘maxmemory’ parameters in rasterOptions() but doing so greatly increases processing time, especially considering that some year’s mosaics will have to be built from 100+ scenes. I am also familiar with gdalUtils::mosaic_rasters which is faster but I am mosaicking based on median value which is not an option with that function (as far as I can tell).
Is anyone aware of a method for mosaicking in parallel or otherwise speeding up the process? Unfortunately getting more RAM is not an option at the moment. Happy to share more information about my workflow if it helps at all.
Thanks in advance,