Labeling Question

[Stephen Woodbridge]

magnus gmail wrote:
> Hi,
>  
> First question:
> Does mapserver *"label collision mediation" *work per layer or is it 
> done accross all the layers in the map?

It is done across all labels the are put in the label cache. This 
basically means Yes across all layers in the map. The priority is based 
on last into the cache is first out.

The idea being that as you draw layers from the top of the mapfile to 
the bottom of the mapfile you are imaging the most important stuff last 
on the upper most visual layer of the map. These last layers being most 
important get their labels rendered first. As more and more labels get 
draw there is less and less free space for labels from the lower (less 
important layers so they tend to get bumped off the map.

You a little control over this if you are willing to split rendering and 
annotation of a layer into two layers at the cost of scanning that data 
twice. Then you can place the annotation layer higher in the layer stack 
to get higher priority.

-Steve W.