very well! I did it by hand till now (well I do not have so many raster in GRASS and ... how often do one need to change the color table?)
could you post this script on GRASS-Addons site? (http://grass.gdf-hannover.de/twiki/bin/view/GRASS/GrassAddOns) Jáchym On Sun, Oct 16, 2005 at 12:35:14PM +0200, Andrea Antonello wrote: > Some time ago I was dealing with mapserver getting maps from a GRASS > location. > The maps are all floating point maps and as you (whoever interested) probably > followed in a few mails, the result of most of my maps simply resulted in a > single color layer (in my case it was yellow). > Frank Warmerdam helped me to solve what was solvable and workaround what was > "workaroundable". > The following is an extract and resume of the mails exchange. > Any reply and correction is appreciated. > > Alright, the problem was not only one, but a bunch concurring: > 1) GRASS novalues are not supported and give problems > > Running gdalinfo -mm on the map, we find that part of the problem is that > nodata values are being treated as "nan" (not a number). GDAL and mapserver > do not know how to excluse "nan" nodata values from the min/max calculation > so the autoscaling gets all screwed up. > > Here we can see it in the gdalinfo output: > <SNIPPET> > Band 1 Block=385x1 Type=Float64, ColorInterp=Palette > Min=0.000 Max=229172.410 Computed Min/Max=nan,nan > NoData Value=nan > <SNIPPET> > > Therefore the min and max have to ge defined and supplied to the map file > with > the following: > PROCESSING SCALE=min max > > 2) There is a problem with the creation of color ramps in the case of a big > number of not homogeneous distributed values: > > <SNIPPET> > Color Table (RGB with 100001 entries) > 0: 0,0,0,0 > 1: 255,255,0,255 > 2: 255,255,0,255 > 3: 255,255,0,255 > ... > <SNIPPET> > > This is why I had a yellow map. The first 256 values of the color table were > used by MapServer for the after-scaling values. Effectively the first 256 > entries of the color table are all shades of yellow. > > 3) MapServer does not support the GRASS color rules metadata > > <SNIPPET> > Metadata: > COLOR_TABLE_RULES_COUNT=5 > COLOR_TABLE_RULE_RGB_0=1.000000e+00 4.583448e+04 255 255 0 0 255 0 > COLOR_TABLE_RULE_RGB_1=4.583448e+04 9.166896e+04 0 255 0 0 255 255 > COLOR_TABLE_RULE_RGB_2=9.166896e+04 1.375034e+05 0 255 255 0 0 255 > COLOR_TABLE_RULE_RGB_3=1.375034e+05 1.833379e+05 0 0 255 255 0 255 > COLOR_TABLE_RULE_RGB_4=1.833379e+05 2.291724e+05 255 0 255 255 0 0 > <SNIPPET/> > > The metadata contains the coloring rules that should be applied. However, > mapserver does not currently know how to use this sort of color rule > metadata. For now the only solution is to recreate classes that are value > similar. One problem though is that MapServer classes don't allow applying a > range of color to a range of values like GRASS (or QGIS). Applying own > CLASSes in the LAYER makes mapserver ignore the color table. > > The CLASSes option has two main drawbacks: > > a) The CLASS does not allow color ranges. There is no big solution (only > workarounds), if not to wait on the new range based class coloring that Bill > Binko has been working on. An implementation of that is available in 4.6.x > but it is under revision. > > b) If we decide to create a set of CLASS rules to get the map drawn "as if" > it > was interpolated, you will need to create a lot of rules, which gives big big > performance problems in drawing the map. This can however be solved with a > PROCESSING command. Here the explanation: > The problem is that the class lookup is done once for each "bucket" in the > lookup table and that by default there are 65536 buckets. It helps a lot to > add the following line in the LAYER definition: > > PROCESSING "SCALE_BUCKETS=200" > > This basically alters the resolution of the lookup table but substantially > accelerates things. > > > > After some testing on what would be the best to do for now, I'm now letting > the following bash script snippet for automated creation of the raster part > mapfile. It contains the solutions and workarounds reported in this document: > > # the path to the grass cellheader file > absolutepath=$mapsetpath/cellhd/$i > > echo "LAYER" > rastertmpfile > echo " NAME $i" >> rastertmpfile > echo " TYPE RASTER" >> rastertmpfile > echo " STATUS ON" >> rastertmpfile > echo " DATA \"$absolutepath\"" >> rastertmpfile > > # extract the min and max > minmax=`gdalinfo -mm $absolutepath | grep Min | awk -F "=" '{print $2, > $3}' | awk '{print $1, $3}'` > # extract the gdal computed min and max > gdalrange=`gdalinfo -mm $absolutepath | grep "Computed Min" |awk -F > "Computed Min/Max=" '{print $2}' | awk -F "," '{print $1}'` > > > # if gdal has problems with colortables and novalues, it is not able to > compute the range, > # therefore we have to supply it and create a set of ad hoc colorrules > if [ "$gdalrange" == "nan" ] > then > # minmax has the format "123 234", so just extract them > min=`echo $minmax | awk '{print $1}' | awk -F "." '{print $1}'` > max=`echo $minmax | awk '{print $2}' | awk -F "." '{print $1}'` > > # define a default colortable, rainbow of grass, but with "bin + 1" > number of rules, > # to get more colors and give the sensation to be interpolated > bins=19 > delta=$((($max-$min)/$bins)) > > if [ $delta -ne 0 ] > then > colors[1]="255 255 0" > > colors[2]="195 255 0" > colors[3]="130 255 0" > colors[4]="65 255 0" > > colors[5]="0 255 0" > > colors[6]="0 255 65" > colors[7]="0 255 130" > colors[8]="0 255 195" > > colors[9]="0 255 255" > > colors[10]="0 195 255" > colors[11]="0 130 255" > colors[12]="0 65 255" > > colors[13]="0 0 255" > > colors[14]="65 0 255" > colors[15]="130 0 255" > colors[16]="195 0 255" > > colors[17]="255 0 255" > colors[18]="255 0 195" > colors[19]="255 0 130" > colors[20]="255 0 65" > > > # add the processing commands > echo " PROCESSING \"SCALE=$min $max\"" >> rastertmpfile > echo " PROCESSING \"SCALE_BUCKETS=100\"" >> rastertmpfile > > > # create the CLASSes, labeling them with the pixel value > first=$min > second=$(($min+$delta)) > for j in `seq 1 $bins` > do > echo " CLASS " >> rastertmpfile > echo " NAME \"$first\"" >> rastertmpfile > echo " EXPRESSION ([pixel] >= $first and[pixel] < > $second)" >> rastertmpfile > echo " COLOR ${colors[$j]}" >> rastertmpfile > echo " END" >> rastertmpfile > first=$(($first+$delta)) > second=$(($second+$delta)) > done > > # add a last CLASSes, due to bash maths limitations > echo " CLASS " >> rastertmpfile > echo " NAME \"$max\"" >> rastertmpfile > echo " EXPRESSION ([pixel] >= $first and[pixel] < $max)" >> > rastertmpfile > echo " COLOR ${colors[20]}" >> rastertmpfile > echo " END" >> rastertmpfile > fi > fi > > > > Hope this helps someone, the script is not very stylistic, but at least it > does the job for me. :) > > Ciao, > Andrea > > > > > -- > ____________________________________________________________________________ > HydroloGIS - Environmental Open Source Solutions > www.hydrologis.com > > Andrea Antonello > Environmental Engineer > mobile: +393288497722 > > "Let it be as much a great honour to take as to give learning, > if you want to be called wise." > Skuggsja' - The King's mirror - 1240 Reykjavik > ____________________________________________________________________________ -- Jachym Cepicky e-mail: [EMAIL PROTECTED] URL: http://les-ejk.cz GPG: http://les-ejk.cz/gnupg_public_key/ ----------------------------------------- OFFICE: Department of Geoinformation Technologies LDF MZLU v Brně Zemědělská 3 613 00 Brno e-mail: [EMAIL PROTECTED] URL: http://mapserver.mendelu.cz Tel.: +420 545 134 514
