Changes between Version 3 and Version 4 of Processing/NextMapDEMs

Timestamp:

Nov 29, 2007, 11:12:43 AM (17 years ago)

Author:

benj

Comment:

Added procedure for patching in sea-level area for sea areas with no OS data

Processing/NextMapDEMs

@@ -47 +47 @@
 r.out.ascii input=tl17and27 output=/tmp/tl17and27.dem null=0
 }}}
+
+---------
+To add a zero-level area to a map (ie sea level):
+
+In GRASS: 
+{{{
+# Restrict active region to area you're interested in - must use eastings/northings, lat/long seems to have problems determining valid values
+g.region n=601000 e=451000 s=579000 w=389000
+
+# Check region is restricted correctly
+g.region -gb
+
+# Create vector map of active region, output param is name of output map
+v.in.region output=v_sealevel
+
+# Convert vector map to raster map
+v.to.rast input=v_sealevel output=r_sealevel use=val value=0.0
+
+# Create raster maps for areas with OS data as first line only in section above
+r.in.gdal -e input=/data/aegean1/nextmap_dems/neodc/by_tile/by_product/dsm/ny/ny98/ny98dsm/w001001.adf output=ny98
+r.in.gdal -e input=/data/aegean1/nextmap_dems/neodc/by_tile/by_product/dsm/ny/ny99/ny99dsm/w001001.adf output=ny99
+...
+
+# Patch raster maps together as section above
+# NOTE SEA LEVEL MAP MUST BE LAST IN LIST, since Grass starts with a blank map and adds patched raster maps in order
+r.patch input=ny98,ny99,...,r_sealevel output=map_with_added_sea_level
+
+# Create DEM from raster map as section above
+r.out.ascii input=map_with_added_sea_level output=/tmp/map_with_added_sea_level.dem null=0
+}}}