[Mapserver-users] Projection Help

[Frank Warmerdam]

Paul VanDyke wrote:
> Most of my raster images are working great and I am very thankful to
> those who helped me.  However, I am having problems with a few of my
> rasters and I'm scratching my head...
> 
> I am adding them as a layer to my ArcMap project, doing the
> georeferencing, then exporting them out.  I've gotten a few to work, but
> others haven't.  The last one I did showed up on my MapServer map about
> 100 miles south of where it should have been.  I've tried playing with
> the projection in my .map file and I've tried defining the spacial
> information in ArcCatalog.  I realize that I don't have the
> knowledge/background/training to do the job that I'm doing, and so I am
> asking for help from this community.  If you can provide me with any
> links/websites with further information, I'd be very appreciative.  If
> you can tell me why my raster displays 100 miles south (roughly) of
> where it's supposed to, I'd be indebted.
> 
> The map in question is Map 9 at http://209.165.152.73 and you'll have to
> zoom out to the south to see what I'm talking about.

Paul,

This isn't much for us to go on.

Where did you get the data?  Did it come with any coordinate system
information or other metadata that might be helpful?  Can you go back
to the source to get such information?  Does it display properly in ArcMap?
What projection definition are you using now?  Why?  Do you have other
layers that are working properly?  What coordinate system are you using
for them?

A 100 mile error could be the result of a number of things.  Perhaps you
are using the wrong state plane zone, or are missing false easting/northings.
What it is not is a datum/ellipsoid error since those errors would be tiny
by comparison.

Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent