[mapserver-users] help with converting tiff to a shp file

[Gerald Buckmaster]

Greetings,

It sounds like a job for the GeoTIFF Specification.  You can use geotifcp
with the -g argument to install metadata, then use listgeo -tfw to write the
worldfile.

GeoTIFF Metadata is nothing more than a text file that looks something like
this:

Geotiff_Information:
   Version: 1
   Key_Revision: 1.0
   Tagged_Information:
      ModelTiepointTag (2,3):
         0                0                0
         -110.410032      33.2834107       0
      ModelPixelScaleTag (1,3):
         0.000364376663   0.000323906075   0
      End_Of_Tags.
   Keyed_Information:
      GTModelTypeGeoKey (Short,1): ModelTypeGeographic
      GTRasterTypeGeoKey (Short,1): RasterPixelIsPoint
      GTCitationGeoKey (Ascii,11): "CLARKE1866"
      GeogCitationGeoKey (Ascii,11): "GEOGRAPHIC"
      End_Of_Keys.
   End_Of_Geotiff.

I believe you would most likely set the ModelTiepointTag to (8,3)
to handle your pixel/geocoord/elevation triplets.  I've never seen
anyone use anything but 0 for the vertical.  The example given
in the link below negates the use of ModelPixelScaleTag, which
basically means clients (software) are not allowed to infer that there
is a simple linear relationship between the raster data and the
 geographic model coordinate space.  That might be a problem
with some software...someone would need to try out with Mapserver
other than me, as I am officially on vacation when this email transmits.

More details about this can be read at:
http://www.remotesensing.org/geotiff/spec/geotiff3.html#3.2.1.

I highly recommend the entire Specification for late-night reading ;^)


Respectfully,

Gerald Buckmaster
www.imagery-analyst.com



----- Original Message -----
From: <woodbri at swoodbridge.com>
To: "Grant Marblestone" <GrantM at ATSER.com>;
<mapserver-users at lists.gis.umn.edu>
Sent: Tuesday, August 27, 2002 16:24
Subject: Re: [mapserver-users] help with converting tiff to a shp file


> Or another way to think about the problems is:
> How could you come up with a world file for the tiff, if you know the
> lat/long of the end points of the four runways. So if you know the
> lat/long of eight pixels in the TIFF what would you have to do to
> make a world file?
>
> Anybody have a clue?
>
> -Steve
>
> On 27 Aug 2002 at 16:55, Grant Marblestone wrote:
>
> >
> > I have a tiff (top image) of an airport, and thanks to steven
> > woodbridge, i also have a shp file with the runways of this airport.
> > I wish to convert the tiff to shp using perhaps the shp file i have
> > of the runways to line it up. Anyone here have any experience with
> > this and an easy way to do this? I know it wont be exact but i am
> > hoping to get as close as possible this way.
> >
> > Thanks for any input you can provide,
> >
> > Grant
>
>