The MERIT DEM is a global scale terrain DEM at 3 arcsecond resolution with coverage from 60 degrees South to 90 degrees North. So, it excludes Antarctica but includes the Northern Latitudes, which is a considerable improvement over similar DEM’s derived from Shuttle Radar Topography Mission (SRTM) data. It was developed by Dai Yamazaki at the University of Tokyo.
When you convert a raster to MRR format, and then convert the MRR back to a raster in the original format, the size of the raster almost always changes. Why is this and what is going on behind the scenes? In this article I explain some of the concepts around raster size in an MRR format raster, exploring concepts like Grid Size, Cell Range, Valid Cell Range and Extant Tile Boundary. I also explore the issues around the file size of an MRR format raster, and what properties affect file size.