[Mapserver-users] [gis newbie] Questions about EXTENT variable

[P Wilkerson]

I have a simple PHP Mapscript that works when I use the EXTENT statement and
tiff file that came with the gmap75 demo.  However, when I attempt to use a
different map (Boston) and change only the EXTENT statement and tiff file,
Mapserver returns a blank page.

Would somebody please explain what is going on and help out by providing a
valid extent statement?

Demo     EXTENT -2200000  -712631 3072800 3840000
Boston   EXTENT  234503.759398496 899884.343580152 238052.631578947
902250.994765712

Does Proj.4 Cartographic Projections Library have anything to do with this?

Also, The TFW world files seemingly have different coordinate systems as
well.

Any help is warmly appreciated!

Peter

----------------------------------
DEMO MAP FILE

MAP
  NAME Demomap
  SIZE 600 400
  IMAGECOLOR 255 245 220
  # FONTSET symbols/fonts/fonts.list
  # SHADESET symbols/shade.sym
  # MARKERSET symbols/marker.sym
  # LINESET symbols/line.sym
    EXTENT -2200000 -712631 3072800 3840000
  UNITS meters
#  SHAPEPATH "E:/ms4w/Apache/htdocs/map01/data/"

WEB
  IMAGEPATH "/ms4w/tmp/ms_tmp/"
  IMAGEURL "/ms_tmp/"
END

LAYER
#  DESCRIPTION "Base Map: DemoMap"
     NAME "boston1868"
STATUS DEFAULT
     TYPE RASTER
     DATA "E:/ms4w/Apache/htdocs/data/bath_mapserver.tif"
END # Layer for base map


END # Mapfile
 ----------------------------

BOSTON MAP FILE

MAP
  NAME boston1868
  SIZE 600 400
  IMAGECOLOR 155 145 220
     EXTENT  234503.759398496 899884.343580152 238052.631578947
902250.994765712
     EXTENT -2200000 -712631 3072800 3840000
  UNITS meters

WEB
  IMAGEPATH "/ms4w/tmp/ms_tmp/"
  IMAGEURL "/ms_tmp/"
END

LAYER
     NAME "boston1868"
     STATUS ON
     TYPE Raster
     DATA "E:/ms4w/Apache/htdocs/data/boston1868.tif"
END # Layer for base map


END # Mapfile