Jukka,
If you look at RFC 81, it is likely that using this placement algorithm
with leader lines would also work well with these kinds of parcels. It
would be interesting to see how they determine the font size. It looks
like it might be based on a function of the horizontal width of the
polygon at the label point. It is not clear to me how they compute the
label point based on these images. I think they use the leader lines if
the horizontal width of the polygon at the label point is less than some
%age of the label length.
I just updated this ticket.
https://github.com/mapserver/mapserver/issues/3948
You guys might want to watch this ticket also and add any additional
comments to this ticket so that they are all captured in one place.
Thanks,
-Steve W
On 9/4/2012 2:59 PM, Rahkonen Jukka wrote:
Hi,
The polygons in the data are cadastrial parcels and user wants that
each parcel could be identified right. GetFeatureInfo is not enough
because he wants also printed maps. Therefore each parcel should have
a label that is readable in some scale. That is not always easy
because the size of parcels varies a lot.
Here is a reference implementation by the National Land Survey of
Finland:
http://www.paikkatietoikkuna.fi/web/fi/kartta?zoomLevel=10&coord=271051.5_6947937&mapLayers=base_35+100+!default!,90+100+,99+100+&showMarker=false&forceCache=true
NLS has decided to use vertical labels with variable font size for
keeping the label text usually inside their polygons. Sometimes there
seems to be also leader lines. The result is rather readable but I
believe that labels have at least partly set by hand. In the NLS
service the labels comes from a readily rasterised layer and they are
shown only on three highest zoom levels.
Here is another place with very long and narrow parcels. The NLS
labeling system does not suit here very well for web browsing because
labels are often in a fixed place outside the map window.
http://www.paikkatietoikkuna.fi/web/fi/kartta?zoomLevel=10&coord=227539.5_6999494&mapLayers=base_35+100+!default!,90+100+,99+100+&showMarker=false&forceCache=true
-Jukka-
Stephen Woodbridge wrote:
Jukka,
Based on your sample image you probably want something like ANGLE
AUTO
on a polygon to try to compute the longest line that you can insert
into the polygon and then label along that. That would do two things,
compute an ideal label point and whatever angle you need to position
the text.
But no this does not exist in mapserver. There are a bunch of
label
enhancement tickets and a lot of work has been done recently in this
area. You could add some of this thread to an appropriate ticket or
open a new one if there isn't already one.
6.2 also have offset labels with leaders. In this case it creates
a
label and draws an arrow to point at the feature. Thomas posted some
examples to the list at some point. See:
http://mapserver.org/development/rfc/ms-rfc-81.html and google:
mapserver offset labels rfc81
I do have a ticket open for labeling a polygon along an interior
or
exterior edge. The idea being that I want to label country borders.
I want the label to FOLLOW the border, but it needs to be offset
either inside or outside the polygon. If this were implemented then
it would work for your case if you could live with the label inside
and along an edge. But it has not been implemented yet.
-Steve W
On 9/4/2012 11:13 AM, Lime, Steve D (DNR) wrote:
It's tough to know what I'm looking at from the picture. What does
the layer definition look like?
At the moment polygon label point computation tries a couple of
approaches get a label point inside the polygon: 1) compute a
center of gravity 2) if that computation doesn't work (e.g. point
is too close to the edge) then a scanline-based process is used to
sample possible positions. The mid-point of the longest y sample is
used.
It's always trade-off with speed and the above seems a happy
medium.
Steve
-----Original Message----- From:
[email protected]
[mailto:[email protected]] On Behalf Of
Rahkonen Jukka Sent: Tuesday, September 04, 2012 9:48 AM To:
'Mapserver-Users ([email protected])' Subject: Re:
[mapserver-users] Still impossible to force labels inside their
polygons?
Hi,
Thank you for the answer. A little screenshot shows an example
with two label points inside one polygon and one polygon without a
label point at all. Perhaps we could have more accurate polygon
label positioning on our wish list.
-Jukka Rahkonen-
Lime, Steve D (DNR) wrote:
Aihe: RE: [mapserver-users] Still impossible to force labels
inside their polygons?
Yes, still impossible. POSITION CC + MINFEATURESIZE AUTO will
get you close. However, MINFEATURESIZE AUTO uses bounding box
checks and doesn't intersect a feature geometry with its label
geometry.
Steve
-----Original Message----- From:
[email protected] [mailto:mapserver-users-
[email protected]] On Behalf Of Rahkonen Jukka Sent:
Tuesday, September 04, 2012 9:17 AM To: 'Mapserver-Users
([email protected])' Subject: [mapserver-users]
Still impossible to force labels inside their polygons?
Hi,
Is the short answer by Stephen Woodbridge "No" in the tread
http://osgeo-
org.1560.n6.nabble.com/force-labels-to-fit-in-polygons-td4549296.html
still valid?
I have been trying to label a polygon dataset with Mapserver 6.2
beta2 and some labels keep on falling outside their polygons.
By the way, the thread contains an advice that does not work for
me: " By the way, PROCESSING "LABEL_NO_CLIP=ON" will fix the
label point at the polygon center. -SteveW "
Is the solution to create a new layer with point-on-surface
function and label then this point layer?
-Jukka Rahkonen- _______________________________________________
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