order of labels in kamap

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order of labels in kamap

Sacha Black

hi all,

i searched the archives, but couldn't find mentions of this issue, so i'm just looking for confirmation of what i am seeing with labels when transitioning an old map file to kamap.

in regular mapserver, the behaviour is to draw all layers in order from top to bottom of the mapfile, and then to reverse direction and draw all the labels from bottom to top. this minimizes label/feature collisions, prioritizes point labels over line labels over polygon labels, and seems to balance label placement across the map

in contrast:

kamap draws each set of labels with its corresponding layer, so that labels are placed regardless of collisions with labels on other layers, and labels can be "overlain" and partially hidden by features higher up in the stack... which can lead to some odd/ugly cartographic results.

is there something i am missing here? the above suggests that all labeling in a kamap map file should be done at the bottom of the map file in a new group (so labels are last to draw, and the overlay probelm is fixed) .... is this the intention? would the result of doing this be comparable to straight mapserver output?  i'm a bit worried about hitting an upper limit of allowed layers if a large number need to be repeated as annotation layers....

sacha
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Re: order of labels in kamap

pagameba
Sacha,

if you are rendering all the layers as a single group then you should  
be seeing mapserver's normal behaviour.

if you have separated each layer into its own group so that it is  
separately controllable in the client, then labels will be rendered  
with each layer independently of all other labels.  What ka-Map does  
in this case is turn off all other layers so mapserver doesn't take  
other labels into consideration.

I don't know of a good way around this if you want to have separate  
layer groups and those layer groups have labels.  I'm not sure that  
creating separate annotation layers would solve the problem.

Cheers

Paul

On 2-Nov-06, at 9:50 PM, Sacha Black wrote:

>
> hi all,
>
> i searched the archives, but couldn't find mentions of this issue,  
> so i'm just looking for confirmation of what i am seeing with  
> labels when transitioning an old map file to kamap.
>
> in regular mapserver, the behaviour is to draw all layers in order  
> from top to bottom of the mapfile, and then to reverse direction  
> and draw all the labels from bottom to top. this minimizes label/
> feature collisions, prioritizes point labels over line labels over  
> polygon labels, and seems to balance label placement across the map
>
> in contrast:
>
> kamap draws each set of labels with its corresponding layer, so  
> that labels are placed regardless of collisions with labels on  
> other layers, and labels can be "overlain" and partially hidden by  
> features higher up in the stack... which can lead to some odd/ugly  
> cartographic results.
>
> is there something i am missing here? the above suggests that all  
> labeling in a kamap map file should be done at the bottom of the  
> map file in a new group (so labels are last to draw, and the  
> overlay probelm is fixed) .... is this the intention? would the  
> result of doing this be comparable to straight mapserver output?  
> i'm a bit worried about hitting an upper limit of allowed layers if  
> a large number need to be repeated as annotation layers....
>
> sacha
> _______________________________________________
> ka-Map-users mailing list
> [hidden email]
> http://lists.maptools.org/mailman/listinfo/ka-map-users

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|Paul Spencer                          [hidden email]    |
+-----------------------------------------------------------------+
|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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Re: order of labels in kamap

Sacha Black

thanks paul,

my situation was that I had a group called "transportation" that contained many different road layers plus railroads and ferrylines, and another group called "landmarks" that had layers like schools, parks, tourist attractions, etc.  each group's labels render fine, it was just the collisions between groups that was bugging me.  i'm going to experiment with annotation options, and if that doesn't pan out i'll revert to creating a single base group.

sacha


On 11/2/06, Paul Spencer <[hidden email]> wrote:
Sacha,

if you are rendering all the layers as a single group then you should
be seeing mapserver's normal behaviour.

if you have separated each layer into its own group so that it is
separately controllable in the client, then labels will be rendered
with each layer independently of all other labels.  What ka-Map does
in this case is turn off all other layers so mapserver doesn't take
other labels into consideration.

I don't know of a good way around this if you want to have separate
layer groups and those layer groups have labels.  I'm not sure that
creating separate annotation layers would solve the problem.

Cheers

Paul

On 2-Nov-06, at 9:50 PM, Sacha Black wrote:

>
> hi all,
>
> i searched the archives, but couldn't find mentions of this issue,
> so i'm just looking for confirmation of what i am seeing with
> labels when transitioning an old map file to kamap.
>
> in regular mapserver, the behaviour is to draw all layers in order
> from top to bottom of the mapfile, and then to reverse direction
> and draw all the labels from bottom to top. this minimizes label/
> feature collisions, prioritizes point labels over line labels over
> polygon labels, and seems to balance label placement across the map
>
> in contrast:
>
> kamap draws each set of labels with its corresponding layer, so
> that labels are placed regardless of collisions with labels on
> other layers, and labels can be "overlain" and partially hidden by
> features higher up in the stack... which can lead to some odd/ugly
> cartographic results.
>
> is there something i am missing here? the above suggests that all
> labeling in a kamap map file should be done at the bottom of the
> map file in a new group (so labels are last to draw, and the
> overlay probelm is fixed) .... is this the intention? would the
> result of doing this be comparable to straight mapserver output?
> i'm a bit worried about hitting an upper limit of allowed layers if
> a large number need to be repeated as annotation layers....
>
> sacha
> _______________________________________________
> ka-Map-users mailing list
> [hidden email]
> http://lists.maptools.org/mailman/listinfo/ka-map-users

+-----------------------------------------------------------------+
|Paul Spencer                          [hidden email]    |
+-----------------------------------------------------------------+
|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
+-----------------------------------------------------------------+






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ka-Map-users mailing list
[hidden email]
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