Use of different epsg code

[Brent Fraser]

Antonio,

  The values in the EXTENT must be in the units of the
PROJECTION, so I'm suprised that with "UNITS dd" it works at
all.  The units of the MAP should be "UNITS meters".  An
EXTENT of
"-18000000 -9000000 18000000 9000000" meters is an ok place
to start when you want to show the entire globe.

    The GRID objects have sparse documentation.  The MAXARCS
object specifies the maximum number of lines you want shown
on your map (in one direction), so MAXARCS 1 will try to
draw only one line.  From my notes MAXINTERVAL is "The
maximum number of intervals to try to use.  The distance
between the lines, in layer(?) units.  Most commonly changed
parameter."  Since its in the layer's units, using a
MAXINTERVAL 15 with EPSG:54009 would try to draw a line
every 15 meters (waay too many!), but with EPSG:4326 (a
geographic coordinate system with units of degrees), it
would try to draw one every 15 degrees (much more
reasonable).


    Mapserver uses Proj4 for the coordinate systems
operations.  You may want to look on the Proj4 web site
(http://proj.maptools.org/), but I believe it does support
Aitoff.

Brent Fraser
GeoAnalytic Inc.
Calgary, Alberta

----- Original Message ----- 
From: "antonio" <volpicelli at OATO.INAF.IT>
To: <MAPSERVER-USERS at LISTS.UMN.EDU>
Sent: Thursday, April 19, 2007 3:41 PM
Subject: [UMN_MAPSERVER-USERS] Use of different epsg code


> Hi ,
> I am new of mapserver. I am using mapserver for an
astronomic
> application and I would like to use Mollweide projection
( epsg:54009).
> I am able to draw the graticule ( the ellipse  )  using
this layer
> inside mapfile.
> First of all in the top of mapfile I defined these :
> MAP
>    NAME ASTRO
>    STATUS ON
>
>    #EXTENT -180 -90 180  90    EXTENT -18000000 -9000000
18000000 9000000
>      UNITS dd
>    #IMAGECOLOR 0 123 123
>    TRANSPARENT ON
>    SHAPEPATH "G:/GalexData/TestPoint"
>    CONFIG "PROJ_LIB" "E:/ms4w/proj/nad/"
> .    PROJECTION
>            "init=epsg:54009"
>      END
>
> .
> .
> .
>
> The layer definition for the graticule:
>
> LAYER
>   NAME "Grid"
>   METADATA
>     "DESCRIPTION" "Grid"
>   END
>   TYPE LINE
>   STATUS OFF
>   CLASS
>     NAME "Graticule"
>     COLOR 123 123 123
>  END
>  PROJECTION
>      "init=epsg:4326"
>      #"init=epsg:54009"
>  END
>  GRID
>    MAXARCS 1
>    MAXINTERVAL 15
>  END
> END # Layer
>
>
> So this work but I don't really understand why I have to
define the
> EXTENT as -18000000 -9000000 18000000 9000000 and not
as -180 -90 180  90
> and in the layer "Grid" definition I cannot define the
init=epsg:54009
> but init=epsg:4326 . If I use 54009 , mapserver goes in
stall , it gets
> 98% of CPU and don't end never.
> If now I want draw one polygon shape on this map and I use
this layer :
> LAYER
>  NAME "TestPoint"
>  TYPE POLYGON
>  STATUS ON
>
>  DATA TestPoint
>  PROJECTION
>        "init=epsg:4326"
>  END
>
>  LABELITEM 'tilename'
>  DUMP true
>
>  CLASS
>    NAME "TestPoint"
>    STYLE
>      SIZE 2
>      OUTLINECOLOR 123 123 123
>      COLOR 0 0 255
>        END
>    LABEL
>      MINFEATURESIZE 200
>    END
>
>  END
>
>   METADATA
>      GML_INCLUDE_ITEMS
"tilename,survey,ra,dec,nuvexptime,fuvexptime"
>      WMS_SERVER_VERSION "1.1.1"
>      WMS_FORMAT "image/png"
>      WMS_TITLE "Galex AIS Survey"
>      WMS_ABSTRACT "SDSS DR3 imaging level 0"
>      WMS_SRS "EPSG:4326"
>      WMS_NAME "TestPoint"
>     #WMS_FORCE_SEPARATE_REQUEST "0"       END
>     END
>
> and here too , I have to use epsg:4326 and not 54009.
>
> There are someone that could help me about this and If I
want to change
> the projection from Mollweide to Aitoff  , is it possible
and supported
> by mapserver.
> Thanks
> Antonio