= GRID Object Use in a Mapfile =

And here's the new GRID keyword documentation:

The layer definition
{{{
LAYER

  NAME "SAMPLE GRID"
  PROJECTION 
	  "proj=latlong"
	  "ellps=WGS84"
	  "datum=WGS84"
  END
  TYPE LINE
  STATUS DEFAULT
  CLASS
	COLOR 0 255 128
	  LABEL
		TYPE BITMAP
		SIZE MEDIUM
		COLOR 255 128 89
	  END
  END

  GRID
  END

END
}}}
Will generate a graticule with default arc spacing, arc color RGB 0 255 128 and labeled in decimal degrees with color RGB 255 128 89. Labels will appear at all four of the image edges.

Each arc in the resulting grid is composed of 256 line segments. To render grid arcs with a different number of segments, use the MINSUBDIVIDE and MAXSUBDIVIDE keywords. Setting MINSUBDIVIDE == MAXSUBDIVIDE will always yield exactly the number of segments specified.

To set the format of the grid labels, specify a printf style format string after the LABELFORMAT keyword. The default string is "%5.2f". To get DMS labeling, enter "DDMMSS" as the LABELFORMAT string used by the GRID, and for DM labeling, specify "DDMM".

== The GRID feature ==
{{{
 GRID
	  MINSUBDIVIDE 64
	  MAXSUBDIVIDE 64
	  LABELFORMAT "DDMMSS" 	
 END
}}}
Yields a grid with 64 segments in every arc labeled with degrees, minutes and seconds.

Other keywords behave similarly:

MININTERVAL and MAXINTERVAL allow a range to be set for grid spacing. The interval is specified in the coordinate system of the grid. Since PROJECTION is supported, if your mapserver has PROJ4, the grid may be in any coordinate system supported by PROJ4, and will be projected into the coordinate system of the generated image.

MINARCS and MAXARCS are hints to the code that generates grid intervals regarding when to stop subdividing the range of an axis. The subdivider will try to honor the range specified, or the min/max id only one keyword is present.

Please let me know if there are bugs, questions or comments.

Regards,

John Novak Novacell Technologies www.novacell.com