On Tue, Oct 19, 2021 at 5:37 PM Rahkonen Jukka (MML) < jukka.rahko...@maanmittauslaitos.fi> wrote:
> Hi, > > > > Here is more accurate documentation but only in the text > https://www.mapserver.org/ogc/wcs_server.html > > > > “The convention is that once (wcs|ows)_extent and one of (wcs|ows)_size > and (wcs|ows)_resolution is set in the layer metadata, all the coverage > specific metadata will be retrieved from there. Otherwise the source image > is queried via GDAL, if possible.” > > > > It seems that only wcs_extent is documented in the list of metadata > elements but this is what they do: > > - wcs_extent defines the bounding box or your coverage -> that will go > into DescribeCoverage > - wcs_size is the size of the coverage as pixels -> pixel size can be > computed by extent and size > - wcs_resolution tells the pixel size explicitly -> size of the > coverage in pixels can be computed > > Thanks a lot, Jukka. That all makes some sense as far as it goes, but I'm still not clear on a few details. I have this range of data: 24N to 50N and 125W to 66W which is 26 degrees by 59 degrees. Since the SRTM data has 3 arc-second spacing, that's 1200 pixels per degree plus one for the extra edge so I have tried a number of things without success. 1. Is wcs_size the size FULL range of the tiles that I have? And what is the order? 2. Again, what is the order for wcs_resolution? Are the units degrees since the coordinate system of the original data is EPSG:4326? I've tried all of these, one at a time, and get various errors. (1 / 1200 = 0.00083333...) #"wcs_resolution" "0.00083333 0.00083333" #"wcs_size" "70801 31201" "wcs_size" "31201 70801" In case it's helpful, here's my LAYER definition (with probably extra things I've tried based on my searching and trial & error): LAYER NAME SRTM_3_arc-second_grid METADATA "wcs_label" "SRTM - 3 arc-second grid" ### required "wcs_rangeset_name" "Range 1" ### required to support DescribeCoverage request "wcs_rangeset_label" "Lower 48" ### required to support DescribeCoverage request "ows_extent" "-125 24 -66 50" #"wcs_resolution" "0.00083333 0.00083333" # 1/1200 for 3" spacing? #"wcs_size" "70801 31201" # Not sure of order "wcs_size" "31201 70801" "wcs_bandcount" "1" "wcs_native_format" "SRTMHGT" # What should this be? I can't find examples... "wcs_srs" "EPSG:4326" END TYPE RASTER ### required STATUS ON TILEINDEX "../srtm_3_hgt/srtm_3_hgt-index.shp" # Path is relative to SHAPEPATH TILEITEM "Location" PROJECTION "init=epsg:4326" END END I feel like I must be close. Thanks a lot for any further pointers, carl
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