polygon size and tilemaps

[Stephen Lime]

> Question 1

>http://gis.geosurv.gov.nf.ca/mrights/mapdisplay/mapdisplaylab.html  (it only
>works any sense on IE5.0)

>I have set up mapserver on NT4.0 (DM Solutions compile) using tilemaps to
>index 1:250 000 map layers. I do not have all layers for all 1:250 000 map
>sheets and I did not want to have index maps for all 12 layers so I created
>one index tilemap and used the fields in the .dbf file to list the location
>of the map layers. When a map layer was not present I left the .dbf field
>empty but mapserver gives me an error that
>msOpenSHPFile(): Unable to Access file. ()
>Is there any way around this error? I guess I can fool mapserver but putting
>in a empty shapefile.

There is a compile time option called "IGNORE_MISSING_DATA" that can
be enabled before compiling. Other than that empty shapefiles are the only option.

>Question 2

>Several layers on my map are polygons of water bodies and forest area and
>some of these polygons are quite large with many holes in them. i.e. ocean
>with thousands of islands, One map sheet has 5000 lakes which are holes in
>the land polygon. Mapserver seems a little erratic when it comes to filling
>these polygons with color. It works some times and not others, I am assuming
>it depends on the current clip window. Is there a limit to a polygon size,
>points, pieces?

I've not run into limitations, but then again I may not have the most complex examples.
If you could share the sheet in question I could try using it here where memory is not
an issue. In general each shape is considered independantly so memory usage is
pretty low even with huge polygons. There are no hard limits to polygon parameters.

>Zoom in to the center of the land area on the above URL.

Can't get it to work under MSIE 5.5 so...

>Larry Nolan
>St. John's, Newfoundland, Canada

>voice (709) 729-2168
>email lrn at zeppo.geosurv.gov.nf.ca 

Steve

Stephen Lime
Internet Applications Analyst

Minnesota DNR
500 Lafayette Road
St. Paul, MN 55155
651-297-2937