The MapText site (http://www.maptext.com/) shows you a good collection
of map labeling problems (and how they solve them). The product is
commercial and expensive, but I've heard that it's pretty good.
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: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Reid Priedhorsky
Sent: Wednesday, December 27, 2006 11:18 AM
To: [email protected]
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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