Raster Image and Shapefile Alignment

[Barend Köbben]

That's a whole different game... 
 
You'd basically point to known or recognisable locations in your image (the 'slave') and point to the equivalent point in a geometrically correct  'master', eg. the vector you have, or a scanned map or a set of GPS point, etc.
 
For a theoretical overview, see eg. http://www.cnr.berkeley.edu/~gong/textbook/chapter4/html/sect44.htm
 
In practice, you'd use some basic GIS or Remote Sensing  software that can do that...
 
-- 
Barend Köbben 
International Institute for Geo-information Sciences and  Earth Observation (ITC) 
PO Box 6, 7500AA Enschede (The Netherlands) 
ph: +31-(0)534874253; mobile: +31-(0)622344955

________________________________

From: Bradley Mclain [mailto:bradleym06 at hotmail.com]
Sent: Sun 04/02/2007 22:46
To: Barend Köbben; MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Raster Image and Shapefile Alignment



How would you suggest I go about re-doing the georeferencing?

Brad





>From: Barend Köbben <kobben at itc.nl>
>To: Bradley Mclain <bradleym06 at HOTMAIL.COM>
>Subject: Re: [UMN_MAPSERVER-USERS] Raster Image and Shapefile Alignment
>Date: Fri, 02 Feb 2007 09:19:33 +0100
>
>HI,
>
>The shapefile is in an Australian projection, and your raster has been
>georeferenced to *something*, but there's no telling to what projection
>they
>georef'd it, because there's no projection info in the raster file.
>
>In other words: someone told the raster "you fit in this place in the
>world,
>between XY 1 and XY 2", but they didn't specify in what projection system
>those XY's are. You would suppose to the same projection the vector is in,
>and in that case, the fit will be OK as long as the projection of the shape
>remains the same as it was when the raster was georef'd to it. But if one
>changes that projection, or maybe only the Datum, as tends to happen
>unexpectedly when you transfer files from one GIS to another, things will
>misalign...
>
>To make matters worse, it can also just be a case of sloppy
>georeferencing...
>
>Without knowing the rasterprojection, there's no solution, except re-doing
>the georeferencing...
>
>On 02-02-2007 07:16, "Bradley Mclain" <bradleym06 at HOTMAIL.COM> wrote:
>
> > Umm I know very little about geodata so i'll simply attach the readouts
>from
> > ogrinfo and gdalinfo so you can see for yourself cause i have no idea.
>:)
> >
> > If it helps any they are only out slightly. (as shown in attached
> > screenshot)
> >
> > Bradley Mclain
> >
> >
> >
> >
> >> From: "Gregor Mosheh" <gregor at hostgis.com>
> >> Reply-To: support at hostgis.com
> >> To: "Brad_Mclain" <bradleym06 at HOTMAIL.COM>
> >> CC: mapserver-users at lists.umn.edu
> >> Subject: Re: [UMN_MAPSERVER-USERS] Raster Image and Shapefile Alignment
> >> Date: Thu, 1 Feb 2007 23:02:05 -0700 (MST)
> >>
> >>> Ok here is the sitution I have a raster image and shapefile data but
>the
> >>> two do not line up correctly.
> >>
> >> Are you positive that they're both in the same projection? Or, do you
>know
> >> the projection for each one? I've had so many annoyances in the past
>where
> >> something was in "CA State Plane II" and then had to figure out which
>of
> >> the five CA State Plane II projections it really was. :)
> >>
> >> If you know the projection for each, be sure to specify it in your
>mapfile
> >> using a PROJECTION block in your LAYER block. You can probably get more
> >> help on that once we know a bit more about the matter.
> >>
> >> Best of luck, Brad.
> >>
> >> -G
> >>
> >
> > _________________________________________________________________
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