Frank,
Thanks for you help. I finally started reading the fine print (NAD27/83, HARN, x_0s and to_meters) and got the system running using 32046 for the vectors and 2924 for the rasters. The system works great. I never new there were so many different coordinate systems for one state.
Paul A. Malabad
Director of Information Technology
City of Harrisonburg
(540) 432-7706
------ Original Message ------
From: Frank Warmerdam <[EMAIL PROTECTED]>
Date: Saturday, July 8th, 2006 5:13 PM EDT
To: Paul A Malabad <[EMAIL PROTECTED]>
Subject: Re: [UMN_MAPSERVER-USERS] raster vs shp files extents don't match
Paul A Malabad wrote:
> I have found out that the DIgital orthos are Virginia State Plane
> Coordinate system. Through the metadata on the dvd, I found that
> although the discs read VASPCS North, The metadata actually refers to
> the VASPCS south. I metadata also refers to the units in US survey
> foot. whereas the epsg file refers to metre. I have tried using the
> information from the meta to create a separate projection, but it is not
> working correctly. Can you see anything wrong in my translation.
> PROJECTION
> "init=epsg:102746"
> END
Paul,
The ESRI coordinate system number 102746 is in US feet,
but I believe that the vector coordinates are in meter
based on the scale of the values. So I'm not sure that 102746
is right for the vectors. I think EPSG:32146 (VA SPCS North / meter)
or EPSG:32147 (VA SPCS South / meter) would be more appropriate.
EPSG 32146 can be described with the following proj.4 string:
+proj=lcc +lat_1=39.2 +lat_2=38.03333333333333 +lat_0=37.66666666666666
+lon_0=-78.5 +x_0=3500000 +y_0=2000000 +ellps=GRS80 +datum=NAD83
+units=m +no_defs
> PROJECTION
> "proj=latlong"
> "ellps=GRS80"
> "datum=NAD83"
> "lat_0=36.333333334"
> "lat_1=36.766666667"
> "lat_2=37.966666667"
> "lon_0=-78.5"
> "units=ft"
> END
Note that this definition is ignoring the false easting and northing
which are very important. In my fairly recent file VA SCPS South (ftUS)
is EPSG:2284 and maps to the PROJ.4 string:
+proj=lcc +lat_1=37.96666666666667 +lat_2=36.76666666666667
+lat_0=36.33333333333334 +lon_0=-78.5
+x_0=3500000 +y_0=1000000.0
+ellps=GRS80 +datum=NAD83 +to_meter=0.3048006096012192 +no_defs
Note the important +x_0 and +y_0 values.
So I *think* you want to use EPSG:32146 for the vector layer, and
EPSG:2284 for the raster layer. Then you can set your map level
projection to whichever you wish.
Best regards,
--
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I set the clouds in motion - turn up | Frank Warmerdam, [EMAIL PROTECTED]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | President OSGF, http://osgeo.org
