Psmap flooding example
This is a simple ps.map script demonstrating variable text & queries.
It is based on this mailing list post and considers a hypothetical dynamic flood risk warning map generator.
It builds on the Spearfish catchments generated by the r.watershed help page example. All you need to specify is catchments at risk, the script generates the rest.
screenshot of whole catchment warning:
screenshot of low-lying areas warning:
screenshot of Spearfish catchments:
First we need to generate polygons for low lying ares from each catchment created with the r.watershed help page example.
Next we designate the low lying areas. Ideally this would come from a real-time hydrologic model, but as this is an example we just make something up:
# create danger polygons for each catchment # (homebrew example of predictor for at-risk low-lying areas) r.cost -k in=slope out=slope_cost_from_rivers start_rast=rwater.course r.colors slope_cost_from_rivers col=bcyr -e # choose some threshold. this could be based on hydrologic model output. # for now just set for lower half of slope-costs in the map eval `r.univar -g slope_cost_from_rivers` r.mapcalc "flood.zones = if(slope_cost_from_rivers < $mean, \ rwater.basin, null() )" # convert to vector areas r.to.vect -s in=flood.zones out=flood_zones feature=area v.db.dropcol map=flood_zones column=label v.db.renamecol map=flood_zones column=value,catchment
Next we set the dynamic data, either automatically from model output or though interactive selection & highlight of areas (e.g. a script using the HTMLMAP driver, 'd.what.vect -xft', or d.ask)
# Here we say catchment #6 and #12 are at risk. FLOOD_BASINS=6,12 TIMESTAMP=`date`
The rest is a static template. Here we pass the command through the shell but the input file could be written to a file (taking care to process environment variables) and then passed to ps.map's input option.
# convert catchment list to SQL query FLOOD_BASIN_SQL=`echo $FLOOD_BASINS | \ sed -e 's/^/catchment = /' -e 's/,/ OR catchment = /g'` # generate PostScript image ps.map out=flood_warning.ps << EOF raster elevation.dem # example of dashed lines vlines roads style 000011 where label ~ 'highway' width 0.25 label Highways end vlines rwater_course color grey label Water courses end vareas rwater_basins #change to "flood_zones" vector map for lowlying areas instead of # entire catchment where $FLOOD_BASIN_SQL color red fcolor red width 2 pat $GISBASE/etc/paint/patterns/diag_up.eps label Catchements subject to flood risk end vlegend end text 100% -3% Warning issued $TIMESTAMP font Helvetica-BoldOblique fontsize 12 ref right end end EOF
Finally we convert the output PostScript image to PDF and PNG formats.
# convert to PDF ps2pdf flood_warning.ps # convert to PNG pstoimg -antialias -aaliastext -out flood_warning.png -scale 1.3 \ -crop tb flood_warning.ps
The PDF output looks the best.
- EPS hatch pattern renders in gv and PNG with black boxes behind lines??
- These do not appear in PDF + acrobat reader.
- EPS hatch patterns are tiled so fill lines have slightly noticeable breaks.
- We need to add something to allow skipping vectors in ps.map's vlegends
- ideas: labelskip [y|N], test for label="" or "none" or "skip"?