[MapServer-users] Solved: WMS: Not all features show, depending on how I zoom and pan

Sat Oct 29 00:59:41 PDT 2022

Thanks Scott and Seth for the help.

You might not remember, because it was several weeks ago, but I had several GML 
source files in EPSG:2100 (Greek grid), and when MapServer was responding to a 
WMS request requesting the data in EPSG:3857 (or 4326), several features would 
be missing.

I converted the data files to shapefiles to see what would happen, and there was 
no improvement. In fact I think it was slightly worse.

Then I upgraded MapServer to 8.0.0 (from 7.6.2) and the problem disappeared. I 
used 8.0.0 and not 7.6.4 because I didn't want to compile it and I installed it 
from Debian bullseye backports, and backports only has 8.0.0. So I don't know if 
the problem exists in 7.6.4.

Regards,

Antonis

On 02/10/2022 17.53, Scott wrote:
> It would be interesting if you could change your 'irrigation-network.gml' into 
> a different format, say .shp, something like:
>
> ogr2ogr irrigation-network.shp irrigation-network.gml
>
> Then try that as a data source in your layer and see if your results differ. 
> This would might help us distinguish between a driver issue and a mapserver 
> issue.
>
>
>
> On 10/2/22 04:51, Antonis Christofides wrote:
>> Hello Seth,
>>
>> Thanks for replying. I experimented and found out there's no difference if I 
>> use something minimal such as what you suggested. What does make a difference 
>> is the CRS: if I tell QGIS to use EPSG:2100 (Greek grid—the CRS the data 
>> files use), then everything works fine. If I use 4326 or 3857, then the 
>> problem appears. Therefore it appears that the problem is with reprojecting 
>> (as the stackexchange user "nmtoken" had suspected). Leaflet seems to be 
>> requesting 3857.
>>
>> What would be the right course of action here? Should I tell Leaflet to do 
>> the reprojection instead? Should I investigate further why mapserver has 
>> trouble reprojecting (and how would I do that)? Should I reproject my data 
>> files (GML) offline and store them in 3857 instead of 2100? Is there any 
>> common/best practice regarding this?
>>
>> Thanks!
>>
>> Antonis
>>
>>
>>
>> On 28/09/2022 17.47, Seth G wrote:
>>> Hi,
>>>
>>> Is there any change if you update the layer to have a single class with a 
>>> simple line (no EXPRESSION, LABEL, MAXSCALEDENOM)?
>>>
>>> E.g.
>>>
>>>         CLASS
>>>             STYLE
>>>                 COLOR 0 0 255
>>>                 WIDTH 6
>>>             END
>>>
>>> Seth
>>>
>>> -- 
>>> web:https://geographika.net
>>> twitter: @geographika
>>>
>>> On Wed, Sep 28, 2022, at 1:03 PM, Antonis Christofides wrote:
>>>>
>>>> Hello,
>>>>
>>>> I have a problem that has already been discussed in stackexchange 
>>>> (https://gis.stackexchange.com/questions/440902/mapserver-wms-not-all-features-show-depending-on-how-i-zoom-and-pan 
>>>> <https://gis.stackexchange.com/questions/440902/mapserver-wms-not-all-features-show-depending-on-how-i-zoom-and-pan>), 
>>>> but without solution so far.
>>>>
>>>> I'm repeating the full text here, but if there's any problem with the 
>>>> images it might be better to go to stackexchange to read it.
>>>>
>>>> Here is how QGIS shows an irrigation network, received by MapServer via WMS 
>>>> and superimposed on OpenStreetMap:
>>>>
>>>> enter image description here
>>>>
>>>> Here is the same thing, but slightly panned to the right:
>>>>
>>>> enter image description here
>>>>
>>>> Several items are obviously missing. In fact there are items missing in the 
>>>> top picture as well. Different items become visible as I zoom and pan 
>>>> differently.
>>>>
>>>> Since this pretty much tells the whole story, I'm not going into more 
>>>> details. MapServer version is 7.6.2 (prepackaged for Debian). The base URL 
>>>> is 
>>>> https://poros.irmasys.com/cgi-bin/mapserv?map=/opt/aira-poros/aira-poros/mapserver/extralayers.map 
>>>> <https://poros.irmasys.com/cgi-bin/mapserv?map=/opt/aira-poros/aira-poros/mapserver/extralayers.map>. 
>>>> Finally, below I paste the interesting parts of the mapfile.
>>>>
>>>> Thanks!
>>>>
>>>> Antonis
>>>>
>>>>
>>>>
>>>>
>>>> |MAP NAME "aira-poros" STATUS ON SIZE 9040 7731 EXTENT 103986.57 3850796.18 
>>>> 1007945.14 4623933.00 UNITS meters PROJECTION "init=epsg:2100" END CONFIG 
>>>> MS_ERRORFILE "/var/log/mapserver/extralayers.log" # [Omitting some 
>>>> OUTPUTFORMAT sections] WEB IMAGEPATH "/var/cache/mapserver/" IMAGEURL 
>>>> "/mapserver_tmp/" METADATA "wms_title" "Aira Poros" "wms_onlineresource" 
>>>> "https://poros.irmasys.com/cgi-bin/mapserv?map=/opt/aira-poros/aira-poros/mapserver/extralayers.map&" 
>>>> <https://poros.irmasys.com/cgi-bin/mapserv?map=/opt/aira-poros/aira-poros/mapserver/extralayers.map&> 
>>>> "wms_srs" "EPSG:4326 EPSG:2100 EPSG:3857" "wms_enable_request" "*" 
>>>> "wms_feature_info_mime_type" "text/html" "wfs_title" "Aira Poros" 
>>>> "wfs_onlineresource" 
>>>> "https://poros.irmasys.com/cgi-bin/mapserv?map=/opt/aira-poros/aira-poros/mapserver/extralayers.map&" 
>>>> <https://poros.irmasys.com/cgi-bin/mapserv?map=/opt/aira-poros/aira-poros/mapserver/extralayers.map&> 
>>>> "wfs_srs" "EPSG:2100 EPSG:4326 EPSG:3857" "wfs_enable_request" "*" END END 
>>>> LAYER NAME "irrigation-network" TYPE LINE CONNECTIONTYPE OGR CONNECTION 
>>>> "irrigation-network.gml" METADATA "wms_title" "Irrigation network" 
>>>> "wfs_title" "Irrigation network" "gml_include_items" "all" "gml_featureid" 
>>>> "id" END STATUS ON PROJECTION "init=epsg:2100" END CLASSITEM 'category' 
>>>> CLASS EXPRESSION '1' STYLE COLOR 0 0 255 OPACITY 50 WIDTH 6 END LABEL COLOR 
>>>> 0 0 255 ANGLE FOLLOW OFFSET 5 99 MAXSCALEDENOM 10000 TEXT "[irri_code]" END 
>>>> LABEL COLOR 0 0 255 ANGLE FOLLOW OFFSET -8 99 MAXSCALEDENOM 10000 
>>>> EXPRESSION (NOT('[Diameter]' = '')) TEXT "D=[Diameter] mm" END END # 
>>>> [Omitting three more classes] END # [Omitting four more layers] END|
>>>> _______________________________________________
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>>>>
>>>
>>
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