[mapserver-users] many raster projections

Andy Colson andy at squeakycode.net
Tue Feb 9 07:14:03 PST 2010


On 2/8/2010 1:31 PM, Fawcett, David (MPCA) wrote:
> Andy,
>
> Assuming that MapServer can find the data, the main reason that you
> wouldn't see any data for the layer is that it doesn't fall within
> the output extent bbox.  (To rule out any data issues, you could
> create a second map file with no projection info and only your 07
> layer.  Run gdalinfo against the 07 data and use the bbox info to set
> your map file extent)
>
> What do you see if you run the gdalinfo utility against the data (or
> one of your tiles) from raster07?
the gdalinfo is impressively long, here is the parts that I think are 
important:

Size is 48980, 49445
Coordinate System is:
PROJCS["NAD83 / UTM zone 15N",
     GEOGCS["NAD83",
         DATUM["North_American_Datum_1983",
             SPHEROID["GRS 1980",6378137,298.2572221010002,
                 AUTHORITY["EPSG","7019"]],
             AUTHORITY["EPSG","6269"]],
         PRIMEM["Greenwich",0],
         UNIT["degree",0.0174532925199433],
         AUTHORITY["EPSG","4269"]],
     PROJECTION["Transverse_Mercator"],
     PARAMETER["latitude_of_origin",0],
     PARAMETER["central_meridian",-93],
     PARAMETER["scale_factor",0.9996],
     PARAMETER["false_easting",500000],
     PARAMETER["false_northing",0],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]],
     AUTHORITY["EPSG","26915"]]
Origin = (429904.000000000000000,4428374.000000000000000)

Image Structure Metadata:
   INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left  (  429904.000, 4428374.000) ( 93d49'16.36"W, 40d 0'9.53"N)
Lower Left  (  429904.000, 4378929.000) ( 93d48'57.36"W, 39d33'25.87"N)
Upper Right (  478884.000, 4428374.000) ( 93d14'50.62"W, 40d 0'19.05"N)
Lower Right (  478884.000, 4378929.000) ( 93d14'44.90"W, 39d33'35.25"N)
Center      (  454394.000, 4403651.500) ( 93d31'57.31"W, 39d46'53.71"N)


my mapfile has: MAP EXTENT 1285920 1377857 1426390 1506589

so, yeah, the origin is not within the bbox.  On an image that works, it 
has:

Origin = (1329809.953999999910593,1463071.948000000091270)

which looks to be within the bbox.  So how do I get the arial moved? 
Why didnt putting the projection in the raster layer (or running 
gdal_translate or gdal_warp) move it into the right bbox?


> Does the spatial reference system
> match what you thought that it was?

Huh?  Does "spatial reference system" == "projection" == "Coordinate 
System"?  I dont know...


>
> It looks like the definition for your output projection does match
> epsg:2816.  http://spatialreference.org/ref/epsg/2816/
>
> If you look at the extent that you are setting in your map file (in
> coordinates of epsg:2816), you aren't covering the southern part of
> the zone.  Did you base your extent on the entire area that you need
> to cover?
I got the bounds from a shapefile, its the largest one and covers 
everything I want to display.  See the ogrinfo below.


>
> Also, you have UNITS set to feet, but your output projection has
> '+units=m'. I would set units to METERS.


Well crap.


  ogrinfo -so countyBoundary.shp countyBoundary
INFO: Open of `countyBoundary.shp'
       using driver `ESRI Shapefile' successful.

Layer name: countyBoundary
Geometry: Polygon
Feature Count: 1
Extent: (1285920.182293, 1377857.531376) - (1426390.260458, 1506589.406771)
Layer SRS WKT:
PROJCS["NAD_1983_StatePlane_Missouri_Central_FIPS_2402_Feet",
     GEOGCS["GCS_North_American_1983",
         DATUM["North_American_Datum_1983",
             SPHEROID["GRS_1980",6378137.0,298.257222101]],
         PRIMEM["Greenwich",0.0],
         UNIT["Degree",0.0174532925199433]],
     PROJECTION["Transverse_Mercator"],
     PARAMETER["False_Easting",1640416.666666667],
     PARAMETER["False_Northing",0.0],
     PARAMETER["Central_Meridian",-92.5],
     PARAMETER["Scale_Factor",0.9999333333333333],
     PARAMETER["Latitude_Of_Origin",35.83333333333334],
     UNIT["Foot_US",0.3048006096012192]]
NAME: String (50.0)
SHAPE_Leng: Real (19.11)
SHAPE_Area: Real (19.11)


That means its in feet, right?  Both my mapfile and OpenLayers are using:
+proj=tmerc +lat_0=35.83333333333334 +lon_0=-92.5 +k=0.999933333 
+x_0=500000 +y_0=0 +ellps=GRS80 +units=m +no_defs

Does that mean mapserver is reprojecting to meters... thats probably why 
OpenLayers can show it, right?  The output of mapserver is meters and 
OpenLayers is expecting meters.  So that's not really bad, right?  But 
if I reproject the shapefiles it'll save me some cpu time, yes?

Would this affect the arials?


Thank you very much with the help on this.

-Andy



More information about the MapServer-users mailing list