[mapserver-users] working with ESRI coordinate systems in proj.db

[Mark Volz]

Hello,

I apologize please ignore my mention of EPSG 4326.  My end result is a WMS map in Web Mercator 3857.  My underlying data is stored in a shapefile that is in WKID 103749 which is a projection has already been included in proj.db  as ESRI as the authority .  The underlying map application is using javascript.  I know that my map is finding proj.db because it MapServer does not complain when I convert UTM 14 to Web Mercator...  but that does not help because the underlying data is not in UTM 14.

Here is how I have the projections of my map is set up:
MAP
  PROJECTION
    "init=epsg:3857"
  END  #end map projection
  LAYER
    DATA 'ParcelsLyon.shp'
    PROJECTION
      "init=epsg:103749" #Error: proj_create: cannot expand init=espg:103749 type=crs
      "init=crs:103749"  # Error: proj_create: cannot expand init=crs:103749 type=crs
      "init=ESRI:103749" #Error: proj_create: cannot expand init=esri:103749 type=crs
      "init=epsg:26914"  #MapServer does not warn about any errors, but of course nothing draws because my data is in a different projection
    END #layer projection
  END #end layer
END #end map

Example request
http://localhost/cgi-bin/mapserv.exe?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&FORMAT=image%2Fpng&TRANSPARENT=true&LAYERS=parcels%2CCityLimits%2CTownships&MAP=%2Fms4w%2Fapps%2Flyondata%2F.%2Fmaps%2Falllayers%2FAllLayers.map&SRS=EPSG%3A3857&STYLES=&WIDTH=1569&HEIGHT=912&BBOX=-10678090.52943604%2C5544408.3738651555%2C-10668156.653791208%2C5550182.55779638


@Bob
I could project my shapefile into any projection.  However, I will hit a wall with my raster layers which I prefer not to project at this time.

Thanks!


From: artclifford at gmail.com <artclifford at gmail.com>
Sent: Thursday, January 6, 2022 7:19 PM
To: Mark Volz <MarkVolz at co.lyon.mn.us>
Subject: RE: [mapserver-users] working with ESRI coordinate systems in proj.db

It's a little unclear to me what you are attempting.
A mapfile can be defined where the map's projection is EPSG:3857 (web mercator) set in a projection block at the map level, and your layer definition can have a projection block set to whatever projection you are using. That tells the map to render in web Mercator but says what projection your layer is stored in so that map server knows when to reproject stuff. I think you know that, but I'm just covering the "is it plugged in" issues and to suggest making sure the right projections are in the right projection blocks.

Although not quite the problem you are having yet, epsg:4326 is wgs84 lat/lon. Web Mercator is: EPSG:3857.

If I remember correctly the projection can be defined for a mapfile projection block using the proj code definition if not the ESPG/numeric code. If that works, it might mean that MapServer isn't using the proj.db file like you expect. Or if it is using a proj.db file it may be located elsewhere. Whether putting the whole proj definition is viable for your ultimate use it would at least identify the problem.

Then there's a question of access. How are you "accessing" things? Are you using WFS? Or are you using a python/php/other script? Are things stored in a shp file or postgis or other database?

If you are using wfs are you passing the desired projection on the request? Also, are you defining the allowed wms/wfs projections?

I'm not sure how much I personally can be of help, but any further context on your setup and what you are attempting that you are free and willing to provide will help folks here narrow down the possibilities.




From: MapServer-users <mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>> On Behalf Of Mark Volz
Sent: Thursday, January 6, 2022 9:19 AM
To: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
Subject: [mapserver-users] working with ESRI coordinate systems in proj.db

Hello,

Could someone help me with setting up MapServer to use a non ESRI projection that is already stored in proj.db?  The coordinate system is for Lyon County, MN #103749 and is stored with ESRI as the authority.  I know that we can set up MapServer to use Web Mercator by setting the adding "init=epsg:4326" to a projection block.  Unfortunately I cannot access my counties coordinate system by setting the projection with "init=esri:103749".

Thank you for any help!

Sincerely,
Mark Volz, GISP

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