This was my thinking when I responsed to Matt below. Based on some of
the new work that Thomas has done I think label leaders are put into the
processed label cache, and that these are avoided also. So based on
Matt's request we could include the road lines also and then the bbox of
the labels would avoid intersecting the lines. Likewise as you have
suggested, the same could be done for polygons. We would just need an
API call that could be used to preload the processed cache with geometry
and a mechanism to trigger loading the data at the layer or class level.
Once an object has been added to the processed label cache, you loose
information about priority so I don't think it is feasible to put
priorities on the features to be avoided because this makes the problem
significantly more complex and probably a multiple pass problem.
-SteveW
On 3/23/2012 2:22 PM, Brent Fraser wrote:
Steve L.,
I was thinking more of a way to avoid certain locations for label
placement. Currently the label cache mechanism "reserves" locations that
already have labels (if I remember correctly), and mapserver iterates
thru the 9 locations to hopefully find one without any existing labels.
My thought was to use that method to create polygons not of label boxes,
but of outlines of feature graphics. and put those in the label cache
(at a much lower priority than the label boxes perhaps?). In a perfect
world, the label would be placed in an "empty" area., or more likely in
an area of a minimal amount of graphics.
Best Regards,
Brent Fraser
On 3/23/2012 10:24 AM, Lime, Steve D (DNR) wrote:
Might the layer masking support described here
http://mapserver.org/development/rfc/ms-rfc-79.html be relevant? One
could create a mask around features you don’t want covered and
reference that in the layers with labels. Problem is you might omit
features to when you really just want to omit labels.
Steve
*From:*mapserver-users-boun...@lists.osgeo.org
<mailto:mapserver-users-boun...@lists.osgeo.org>
[mailto:mapserver-users-boun...@lists.osgeo.org] *On Behalf Of *Matt
McClelland
*Sent:* Thursday, March 22, 2012 10:03 PM
*To:* Brent Fraser
*Cc:* mapserver-users@lists.osgeo.org
<mailto:mapserver-users@lists.osgeo.org>
*Subject:* Re: [mapserver-users] Avoid labels over particular lines
I love this idea
Maybe the ability to give a feature priority level of 'label avoidance'
So features like Contours (that may cover a map) can be given a low
priority,
but features like main roads and points of interest might be given a
high priority so they are always visible.
(I did play with rendering some of these items after the label cache,
but that just meant the labels where now covered by the feature)
This sounds like a lot of work, but I don't know??
Matt :)
On Fri, Mar 23, 2012 at 1:16 PM, Brent Fraser <bfra...@geoanalytic.com
<mailto:bfra...@geoanalytic.com>> wrote:
Steve,
I wonder if it would be possible/economical to extend the label cache
to have some kind of feature density "map"/weighted mask to help in
determining a preferred label location...
Best Regards,
Brent Fraser
On 3/22/2012 6:19 PM, Stephen Woodbridge wrote:
On 3/22/2012 8:09 PM, Matt McClelland wrote:
Hi All
Is there a way in mapserver (6.0) to prevent labels appearing over a map
feature?
I have a highway and I want to prevent labels (town and other names from
other layers) sitting over the highway.
I guess something like Buffer in labels.
No, when you go to process a label it knows nothing about what
features have been rendered. I guess in theory you could add all the
features to the label cache. I guessing that to do this you would need
some keyword at the LAYER level to indicate that these features need
to be added to the label cache, but nothing exists today that would do
this.
You might want to open a ticket for an enhancement and paste the
cotent of your message and my response above into it.
-Steve W
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