On Tue, Nov 1, 2011 at 4:53 PM, Chi Kit Lau <[email protected]> wrote: > Dear GRASS users, > > sorry for the beginner's question. How do I work out the maximum > achievable resolution when rasterizing a vector map on a scale > 1:10000? In other words what is the resolution of a map with a scale > 1:10000?
This may be interesting for you "Cartographic limitations [for vector maps]" http://www.searchmesh.net/default.aspx?page=1817 Markus PS: For raster maps, if you are using a scanner (adapted from our GRASS book): Suppose that the scale of the scanned map is 1:10,000. Thus, one centimeter on the map is equivalent to 10,000cm on the ground. Scan resolution, e.g. 300dpi: 300 lines lines 300dpi = ----------- = 118.11 --------- 2.54cm cm Now we can calculate the on-ground distance that corresponds to the length of a raster cell: distance on the ground 10, 000cm cm m ---------------------------- = --------------- = 84.75 ------ = 0.85 ---- scanned lines per cm 118.11lines line line The resulting value of 0.85m is the spatial pixel resolution of the scanned map at the 300dpi scan resolution. If you want the spatial resolution to be an integer, do the inverse calculation and adjust the scanning resolution accordingly. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
