[Mapserver-users] EXTENT and PROJECTION

[Tyler Mitchell]

Ed's note just reminded me of another point, which I'm not sure you 
answered or not.  Have you got MapServer working with the demo or any 
other data already?

> 
> From: Ethan Alpert [mailto:ealpert@digitalglobe.com] 
> Sent: Monday, April 26, 2004 1:27 PM
> To: mapserver-users@lists.gis.umn.edu
> Subject: [Mapserver-users] EXTENT and PROJECTION

> 
> 
> Hello!
> 
> 
> I spent yesterday scouring the archives of this email list trying to
> find some info that would help me get a handle on displaying 
> geotiff's from my mapserver. I found plenty of posts that ask the 
> same questions but no responses.  :/
> 
> I promise to write up a summary if someone can point me in the 
rightdirection.
> 
> I've learned that if you bork the projection and extents in your 
> mapfile you end up with a nice blank image and no error message. I'm
> somewhat at a loss as to how to go about debugging. So my question 
> is given the following info about a geotiff how do you experts go 
> about setting up PROJECTION and EXTENT?
> 
> Here's the output of listgeo on my image:
> 
> Geotiff_Information:
>    Version: 1
>    Key_Revision: 1.0
>    Tagged_Information:
>       ModelTiepointTag (2,3):
>          0                0                0
>          -5760628         4488331          0
>       ModelPixelScaleTag (1,3):
>          1001.042         1001.042         0
>       End_Of_Tags.
>    Keyed_Information:
>       GTModelTypeGeoKey (Short,1): ModelTypeProjected
>       GTRasterTypeGeoKey (Short,1): RasterPixelIsArea
>       GTCitationGeoKey (Ascii,31): "TIFF 6.0, GeoTIFF Revision 1.0"
>       GeographicTypeGeoKey (Short,1): GCS_WGS_84
>       GeogCitationGeoKey (Ascii,157): "Actual datum is nonstandard, 
> based on sphere with radius 6370997 meters.  Coded in GeoTIFF as 
> WGS84 datum.  The difference is not significant at this scale."
>       ProjectedCSTypeGeoKey (Short,1): User-Defined
>       PCSCitationGeoKey (Ascii,117): "Lambert Azimuthal Equal Area 
> projection with arbitrary plane grid; projection center 100.0 
> degrees W, 45.0 degrees N"
>       ProjCoordTransGeoKey (Short,1): CT_LambertAzimEqualArea
>       ProjLinearUnitsGeoKey (Short,1): Linear_Meter
>       ProjCenterLongGeoKey (Double,1): -100
>       ProjCenterLatGeoKey (Double,1): 45
>       End_Of_Keys.
>    End_Of_Geotiff.
> 
> Projection Method: CT_LambertAzimEqualArea
>    ProjCenterLatGeoKey: 45.000000 ( 45d 0' 0.00"N)
>    ProjCenterLongGeoKey: -100.000000 (100d 0' 0.00"W)
>    ProjFalseEastingGeoKey: 0.000000 m
>    ProjFalseNorthingGeoKey: 0.000000 m
> GCS: 4326/WGS 84
> Datum: 6326/World Geodetic System 1984
> Ellipsoid: 7030/WGS 84 (6378137.00,6356752.31)
> Prime Meridian: 8901/Greenwich (0.000000/  0d 0' 0.00"E)
> Projection Linear Units: 9001/metre (1.000000m)
> 
> PROJ.4 Definition: +proj=laea +lat_0=45.000000000 +lon_0=-100.
> 000000000 +x_0=0.000 +y_0=0.000 +ellps=WGS84 +units=m
> 
> Corner Coordinates:
> Upper Left    (-5760628.000,4488331.000)  (157d29'26.96"E, 40d47' 
8.71"N)
> Lower Left    (-5760628.000,-2784239.130)  (151d38'58.71"W, 
4d43'23.63"N)
> Upper Right   (4279823.260,4488331.000)  (  4d 0'39.82"W, 53d59' 8.05"N)
> Lower Right   (4279823.260,-2784239.130)  ( 61d 9'17.99"W, 11d18' 
6.31"N)
> Center        (-740402.370, 852045.935)  (110d51' 5.84"W, 52d12'27.42"N)
> 
> Here's the borked map file I wrote:
> 
> MAP
>   IMAGETYPE PNG
>   SIZE 600 600
>   SHAPEPATH "data"
>   EXTENT -5760628.000 -2784239.130 4279823.260 4488331.000
> 
>   PROJECTION
>       "proj=laea"
>       "lat_0=45.000000000"
>       "lon_0=-100.000000000"
>       "x_0=0.000"
>       "y_0=0.000"
>       "ellps=WGS84"
>       "units=m"
>   END
> 
> 
> 
>   WEB
>     LOG "/var/www/ms.log"
>   END
> 
>   LAYER
>     NAME land
>     DATA landcvi0201.tif
>     STATUS DEFAULT
>     TYPE RASTER
> 
>   END
> END 
> 
> I've tried all kinds of permutations. I'm assuming the extents 
> should be something other than the extents provided by listgeo but I
> haven't any idea what they should be and would like to know what 
> others do when the get a new image to come up with appropriate extents.
> 
> Thanks!
> 
> -ethan
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