So I have this raster dataset OS Terrain 50 which is 153MB, zipped, on disk.
I import a subset of these ASC into Manifold, importing about 50 of these 10km x 10km tiles, each around 191KB on disk. I then merge these tiles into a single image.
I end up with an image size of 140,000 x 160,000 (this is the rectangle of my AOI but I don't need all the data within that rectangle, 386,103 records, and my Manifold project balloons from about 3GB to 36.5 GB.
Am I missing something here? This seems disproportionate. Am I doing something wrong? I don't see how a small subset of a zipped 153MB dataset can balloon by 30GB. Appreciate that I might have crated some artifacts during the merge, and that potentially storage costs in the sparse matrix are not nill, but this is way beyond what I was expecting.
Is there a more efficient way to undertake what I am trying to do here - get a single, irregularly shaped large, tiled image by combining smaller images?
Using Manifold 184.108.40.206