[mapserver-users] Point query from Mapserver raster

[Rahkonen Jukka (MML)]

Hi,

(Had to clip some text from the bottom because of the size limit of this list)

You do not seem to do anything wrong. Your WMS 1.3.0 EPSG:4326 lat-long BBOX=42.94,-122.09,42.95,-122.08& gets converted into long-lat order and for some reason the lower and higher values are equal {-122.082500,42.942500,-122.082500,42.942500}, thus this is no more a box but a point.
GetFeatureInfo with a small bbox and width=2 and height=2 is a trick that is certainly not heavily tested because the corresponding GetMap is pretty odd despite being valid.  Maybe using slightly bigger BBOX makes Mapserver to query the backend raster with a rectangle instead of a point.
BTW X=1 and Y=1 are not valid in WMS 1.3.0, you are supposed to use i= and j= instead. That makes me think that maybe you could have a try with a full and valid WMS 1.1.0 GetFeatureInfo request with SRS= and BBOX in long-lat order and see if it has any effect on the msProjectRect()

-Jukka Rahkonen-

Lähettäjä: MapServer-users <mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>> Puolesta Carl Godkin
Lähetetty: tiistai 2. marraskuuta 2021 17.06
Vastaanottaja: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
Aihe: Re: [mapserver-users] Point query from Mapserver raster

Hi,

Following Jukka's advice on my elevation point query, I am trying to use WMS GetFeatureInfo,

I've mostly got it working but have a few more questions.  (I am using MS4W 4.0.5 which includes MapServer 7.7.0)

I added a LAYER to my WMS map file:

  LAYER
    PROCESSING "RESAMPLE=BILINEAR"
    NAME SRTM_3_arc-second_grid
    METADATA
      "wms_title"           "SRTM - 3 arc-second grid"
      "ows_extent"          "-125 24 -66 50"
      "wms_include_items"   "all"
    END

    TYPE RASTER
    STATUS ON
    TILEINDEX "srtm_3_hgt-index.shp"
    TILEITEM "Location"
    TEMPLATE "../template.html"
    PROJECTION
      "init=epsg:4326"
    END
  END

and an empty template except for the

<!-- MapServer Template -->

line.  Here's my query:

http://localhost:8080/wms?
  SERVICE=WMS&
  VERSION=1.3.0&
  REQUEST=GetFeatureInfo&
  LAYERS=SRTM_3_arc-second_grid&
  CRS=EPSG:4326&
  BBOX=42.94,-122.09,42.95,-122.08&
  WIDTH=2&
  HEIGHT=2&
  X=1&
  Y=1&
  QUERY_LAYERS=SRTM_3_arc-second_grid

This works fine and returns the elevation I am expecting.  However, the MapServer log complains about a "degenerate rect" every time:

[Tue Nov  2 07:58:44 2021].66000 msProjectRect(): Warning: degenerate rect {-122.082500,42.942500,-122.082500,42.942500}

What am I doing wrong here?   As I posted originally, I am really only interested in a point here.

Thank you very much,

carl

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