Clipping of symbols at the boundary of maps

Stephen Woodbridge woodbri at SWOODBRIDGE.COM
Tue May 3 10:39:36 EDT 2005


jochen wrote:
> Hello list,
> how can I control that symbols and labels are drawn,
> even if the definition point is not inside the map extent.
>

You probably need to generate the map at a larger extent, then clip the
map back to the pixels you want. This will require a little math and
some trial and error to figure out how much more and how to clip it.

Mapserver is very efficient at excluding objects that are outside the
bounding box of the image you are trying to render. When you zoom in to
street level 99.99% of the map objects are out side the image in a US
map and you would not want mapserver to look through all those object to
see if half dozen more might impact the image.

Also for lines the cross the image frame, they are clipped so the label
point will move about because of the clipping.

What are you trying to do? Generate image tiles the align with one
another like google maps?

-Steve W.



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