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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