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 On Mon, Nov 1, 2021 at 12:58 AM Rahkonen Jukka (MML) < jukka.rahko...@maanmittauslaitos.fi> wrote: > Hi, > > > > The WMS GetFeatureInfo should work and the answer in gis.stackexhange > seems to contain all the details that you need for making it to work. > > With WCS what you did is probably the best you can do with Mapserver. With > some other servers you may get a single pixel output by using WCS slicing > (subset=Long(-100)&subset=Lat(22)) or trimming with lowerlimit=upperlimit > (subset=Long(-100,-100)&subset=Lat(22,22)) but Mapserver does not support > either. See https://osgeo-org.atlassian.net/browse/GEOS-9553. > > > > I could not find a link to an answer by Stefan Meissl about why Mapserver > does not support slicing but it was about dimensions. A raster image can be > considered to be two dimensional even when it has only one pixel, but by > the WCS standard each trim is removing one dimension. Slicing DEM with two > axes must return a zero dimensional result and raster formats do not > support that. I still think that subsets with lower=upper limits should > works and return a single pixel output but that does not work with either > Mapserver or Geoserver. See also > https://www.mail-archive.com/search?l=mapserver-users%40lists.osgeo.org&q=subject:%22%5C%5Bmapserver%5C-users%5C%5D+WCS+GetCoverage+request+one++by+one+pixel%22&o=newest&f=1 > > > > > > -Jukka Rahkonen- > > > > > > *Lähettäjä:* MapServer-users <mapserver-users-boun...@lists.osgeo.org> > *Puolesta > *Carl Godkin > *Lähetetty:* lauantai 30. lokakuuta 2021 2.10 > *Vastaanottaja:* mapserver-users@lists.osgeo.org > *Aihe:* [mapserver-users] Point query from Mapserver raster > > > > Hi, > > Now that I have my WMS and WCS servers working well (thanks, list!!), I > have one more thing I would like to figure out how to do. > > > > I want to do point queries on [Lat,Lon] points for their elevation from > the terrain layer I have. > > > > I have done some searching and come across various ideas such as Raster > Query (https://mapserver.org/input/raster.html#raster-query) and a query > template ( > https://gis.stackexchange.com/questions/167239/mapserver-raster-picking-elevation-data) > but haven't found enough information for either to implement it. > > > > I came up with a solution that works fine, but might be considered as > going "All Around the Barn" What works is to add an ASCII output format > to my map file that serves terrain like this: > > > > OUTPUTFORMAT > > NAME XYZ > > DRIVER "GDAL/XYZ" > > MIMETYPE "text/plain" > > IMAGEMODE FLOAT32 > > EXTENSION "txt" > > END > > > > and then use GetCoverage on a small rectangle whose lower-left corner > > is the point whose elevation I want: > > > > > http://localhost:8080/wcs?SERVICE=WCS&VERSION=2.0.1&REQUEST=GetCoverage&coverageid=SRTM_3_arc-second_grid&format=XYZ&subset=Lat(42.948,42.958)&subset=Lon(-122.086,-122.076) > > > > and then take the first line of the returned output file. > > > > What would Mapserver best practice be for a problem like this? > > > > Thanks very much, > > > > carl > > > > > > > > > > > > > > > > >
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