[Geowanking] Looking for a decent map labeling algorithm

[Allan Doyle]

You might be able to pull some labeling algorithms out of OpenLabel -  
http://sourceforge.net/projects/openlabel

	Allan

On Jan 2, 2007, at 11:17, Landon Blake wrote:

> Reid,
>
> I don't know if you are going to find exactly what you are looking  
> for.
> I haven't done extensive work with labeling algorithms, but I've
> sketched some ideas on paper, and no one else was responding to your
> post. I thought I would take a stab at it.
>
> This is what I would do if I needed to design a labeling algorithm.
> Start by placing the label in the location that makes the most  
> sense for
> the "typical" geometry in you spatial layer. For example, on a linear
> geometry that represented a road you'll probably want the center point
> for the label to be in the mid point of the linear feature. You'll  
> also
> want the label aligned along the linear geometry.
>
> Once you have the logic to compute the position of the "default" label
> placement for the layer, start to think about what conflicts might  
> occur
> with the default placement and create rules to resolve the conflict.
> (For example, what do you do if the linear segment is shorter than the
> label at the specified text size? You could shrink the label, move the
> label and show a leader to the linear segment, or place some type  
> of key
> or symbol on the linear segment and have a legend with the road  
> name at
> another location on the map.)
>
> I encourage you to take a look at some of the product documentation  
> for
> other labeling tools. See how they have designed their systems and  
> then
> implement some of those same features with your own logic.
>
> I hope that will get you started.
>
> The Sunburned Surveyor
>
> -----Original Message-----
> From: geowanking-bounces at lists.burri.to
> [mailto:geowanking-bounces at lists.burri.to] On Behalf Of Reid  
> Priedhorsky
> Sent: Wednesday, December 27, 2006 11:18 AM
> To: geowanking at lists.burri.to
> Subject: [Geowanking] Looking for a decent map labeling algorithm
>
> Dear geowankers,
>
> I am writing a Flash web mapping algorithm, and we need a map labeling
> algorithm. I was hoping that you folks might be able to point me in  
> the
> right direction.
>
> Here are our top requirements:
>
> 1. Fast.
> 2. Easy to implement and understand. (I would like to minimize the
> amount of effort I spend learning about map labeling.)
>
> Other requirements:
>
> 1. Currently just needs to label the transportation network; later,
> point and area features too.
> 2. Decent results. (Good/great is not necessary - we can make it  
> better
> later.)
> 3. Doesn't need to work at small scales, say less than 1:24k or so (we
> will punt to MapServer for rendering for scales below a certain
> threshold).
> 4. Must be able to expand the map without needing to relabel  
> everything.
>
> (I.e., panning into a new area means just labeling the new stuff.)
>
> Does this make sense? I am a newbie in this area, so please feel  
> free to
>
> ask follow-up questions.
>
> Any ideas about where I should look would be very welcome.
>
> Many thanks,
>
> Reid
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-- 
Allan Doyle
+1.781.433.2695
adoyle at eogeo.org