[MapServer-users] Clipped labels in mapcache/mapserver map

Thu Nov 3 07:32:55 PDT 2022

Thanks for taking a look Steve!

I wondered about the angle follow as well, but I’ve been hoping its not that as it’d be a real shame to have to lose those. And I’ve tried with both negative and positive values for map edge buffer, but it didn’t seem to make a difference, and I read somewhere (mapserver dcos I guess 😊) that the absolute value is now used.

I’ll try recreating a single metatile and let you know what happens.

/Tom

Fra: Steve Lime <sdlime at gmail.com>
Sendt: torsdag 3. november 2022 14:57
Til: Thomas Ellett von Brasch <Thomas.Ellett at kartverket.no>
Kopi: mapserver-users at lists.osgeo.org
Emne: Re: [MapServer-users] Clipped labels in mapcache/mapserver map

VARSEL: Avsenderen er fra utenfra organisasjonen. Vær trygg på innholdet før du trykker på linker eller åpner vedlegg. Er du i tvil tar du kontakt med IT Servicedesk.

So I checked a map here and found similar settings:

  *   label-level: PARTIALS FALSE,
  *   map-level metadata: "labelcache_map_edge_buffer" "-20"
  *   mapcache: <metabuffer>20</metabuffer>
I don't use the LABEL_NO_CLIP processing directive. The one obvious difference is the negative value for the map edge buffer - I know negative values were originally how that was specified but I thought we generalized that value some time ago.

I wonder if the "ANGLE follow" might be the cause - perhaps there's an error in the size computation of the rotated text - perhaps at different position values? Just guessing though.

The only way to easily debug/test is going to be examining a metatile that results in a clipped label. You could delete an affected tile and then let mapcache generate a replacement. You should be able to pick up the metatile WMS call from the logs.

--Steve

On Tue, Nov 1, 2022 at 8:25 PM Steve Lime <sdlime at gmail.com<mailto:sdlime at gmail.com>> wrote:
Have you tried a larger edge buffer? I suppose that’s tough to to test given the randomness. I’ll check my settings on a similar setup when I’m in the office tomorrow and let you know. It would be interesting to see the corresponding metatile to see if the label is whole there. I wouldn’t think so but having a reproducible test case would help immensely.

Anyone know how to compute a metatile URL for a given tile x/y/z?

—Steve

On Mon, Oct 31, 2022 at 10:16 AM Thomas Ellett von Brasch <Thomas.Ellett at kartverket.no<mailto:Thomas.Ellett at kartverket.no>> wrote:
Hi all,

I'm really struggling to fix a longstanding issue with clipped labels in a couple of our wmts services.
I've tried following the mapserver/mapcache docs and numerous variations of different attributes, but with no luck.

The main problem bug fixing is that the issue seems to be quite random, just popping up here and there.

Examples can be seen in these urls:

https://norgeskart.no/#!?project=norgeskart&layers=1002&zoom=11&lat=6879652.31&lon=167744.51<https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnorgeskart.no%2F%23!%3Fproject%3Dnorgeskart%26layers%3D1002%26zoom%3D11%26lat%3D6879652.31%26lon%3D167744.51&data=05%7C01%7CThomas.Ellett%40kartverket.no%7C19288d48885f49d9d72008dabda33e76%7C7f74c8a243ce46b2b0e8b6306cba73a3%7C0%7C0%7C638030806214888918%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=VjUNKd2JQcg4vZhxqTyF6tgigk3eNpU7TCb6dxZiGj0%3D&reserved=0>

(the 'Stor rar' and 'S' names in the centre of the map)

https://norgeskart.no/#!?project=norgeskart&layers=1002&zoom=6&lat=6440416.41&lon=127931.07<https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnorgeskart.no%2F%23!%3Fproject%3Dnorgeskart%26layers%3D1002%26zoom%3D6%26lat%3D6440416.41%26lon%3D127931.07&data=05%7C01%7CThomas.Ellett%40kartverket.no%7C19288d48885f49d9d72008dabda33e76%7C7f74c8a243ce46b2b0e8b6306cba73a3%7C0%7C0%7C638030806214888918%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=ryy%2BNs3TUSgYqp5%2B24vyas%2FrUevpBLYwWOjhufPQBS0%3D&reserved=0>

('Kristiansan' , which should be 'Kristiansand')

I have "labelcache_map_edge_buffer" "10" in the mapfile and <metabuffer>10</metabuffer> set in the mapcache file.

In the source WMS, the placenames layers are line layers (with very small line geometries used just to give curved lines) and the layers (we have several name layers for the different zoom levels, but they're all set up in the same way) look like (truncated):

LAYER
NAME "N100Stedsnavn"
PROCESSING "CLOSE_CONNECTION=DEFER"
PROCESSING "LABEL_NO_CLIP=True"
TYPE LINE

    CLASS
      NAME "N100 Stedsnavn"
      EXPRESSION ([fmx_rotation] != 0)
      LABEL
                  PARTIALS FALSE
                ANGLE follow
                ANTIALIAS TRUE
                FONT "verdana"
                SIZE [fontsize]
                COLOR [geodb_color]
                ENCODING "UTF-8"
                  PRIORITY [fontsize]
                FORCE FALSE
                  MINDISTANCE 50
                 OUTLINECOLOR 254 254 254
                 POSITION [horizontalalignment]
                 TYPE TRUETYPE
      END
      TEXT "[textstring]"
    END
END

And the tileset definition in the mapcache config file looks like:

<tileset name="norgeskart_bakgrunn">
        <source>norgeskart_bakgrunn</source>
        <cache>norgeskart_bakgrunn</cache>
        <metadata>
            <title>Topografisk Norgeskart og dybdedata og svalbard minus matrikkel</title>
           <abstract>Cache for Norgeskart</abstract>
        </metadata>
        <grid>googlemaps</grid>
        <grid>utm33n</grid>
        <format>PNG</format>
        <metatile>8 8</metatile>
        <metabuffer>10</metabuffer>
</tileset>

Is it possible the metatiles being used in the original seed job and later seeding jobs are different somehow?

Given that the labelcache_map_edge_buffer is set (along with metabuffer) and we have PARTIALS FALSE in the mapfile, I didn't think that cut labels would be possible?

Any thoughts or ideas would be great ☺

Thanks in advance!

Tom

[cid:image001.jpg at 01D8EF99.3F3CBED0]
Tom Ellett von Brasch
Sjefsingeniør
Geodatatjenester
Direkte: 32 11 84 73
Mobil: 45806402
E-post: thomas.ellett at kartverket.no<mailto:thomas.ellett at kartverket.no>

Tlf. sentralbord: 32 11 80 00
www.kartverket.no<https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.kartverket.no%2F&data=05%7C01%7CThomas.Ellett%40kartverket.no%7C19288d48885f49d9d72008dabda33e76%7C7f74c8a243ce46b2b0e8b6306cba73a3%7C0%7C0%7C638030806214888918%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=8iuRUmgN15scbg%2BBY5OfdcpJX49l%2B6B66rEclAJ03JM%3D&reserved=0>

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