Perhaps this is not the place for these questions and I should be posting this observation to the PROJ4 list . . . in any case input would be appreciated. Sorry in advance if this observation is out of place.
So now that I have reminded myself that measuring distance on maps is a difficult matter, I have a further question regarding the distance measuring tools in mapServer (in particular with the use of the Mercator projection). After a little research, the problem regarding measuring distances when using the standard Mercator projection would be a variable issue based on lattitude. This is fairly obvious if we think about the way the Mercator projection works, and perhaps my best solution is to choose a better projection for my area of interest (California - perhaps a version of UTM would give me better measurments - in fact I am reasonably certain it would). But the big questions for me is - since there are errors within the distance measuring tools, do the same errors exist in the scalebar tools?? After measuring a few scalebars and comparing them to paper maps of California it would seem that the answer is yes. All of the scalebars drawn through mapServer are short (using the Standard Mercator between lattitudes 33 and 38). Even though the answer is that there is an error using distances with the Standard Mercator with my system, I am, to say the least, unclear as to where this problem lies . . . PROJ4 problem?? . . . a compile problem?? . . . a GDAL problem?? some other issue??? I am sure that I can fudge a workaround for this, but at the same time . . . any guidance for an eleant solution would be greatly appreciated . . . for reference the following were my build steps: for Proj4 [EMAIL PROTECTED] proj-4.4.9]# ./configure [EMAIL PROTECTED] proj-4.4.9]# make [EMAIL PROTECTED] proj-4.4.9]# make install [EMAIL PROTECTED] proj-4.4.9]# cp ~/epsg /usr/local/share/proj/epsg for GDAL [EMAIL PROTECTED] gdal-1.2.6]# make clean [EMAIL PROTECTED] gdal-1.2.6]# ./configure --with-ogr --without-python --with-xerces [EMAIL PROTECTED] gdal-1.2.6]# make [EMAIL PROTECTED] gdal-1.2.6]# make install [EMAIL PROTECTED] gdal-1.2.6]# /sbin/ldconfig for mapserver [EMAIL PROTECTED] mapserver4.4.2]# rm -f config.cache [EMAIL PROTECTED] mapserver4.4.2]# ./configure --without-tiff --with-threads --with-proj --with-gdal=/usr/local/bin/gdal-config --with-ogr --with-php=../php-5.0.4 --with-gd=/usr/local --with-freetype=/usr/bin --with-pdf --with-wmsclient --with-wfs --with-wfsclient [EMAIL PROTECTED] mapserver4.4.2]# make clean [EMAIL PROTECTED] mapserver4.4.2]# make [EMAIL PROTECTED] mapserver4.4.2]# cp mapserv /var/www/cgi-bin/mapserv_40 [EMAIL PROTECTED] mapserver4.4.2]# cp mapscript/php3/php_mapscript.so /usr/local/php/extensions/php_mapscript_40.so as noted in the earlier post, I am using mapServer with PHP mapscript on a Fedora/apache system and all my data is MapInfo (through OGR) - other than this problem, mapServer has performed much better than commercial software that I have used in the past. thanks tim Tim Norris ps: this has also been posted to the PROJ4 listserv
