GUI to make geotiff metadata

I must be going mad, it cannot be this hard :)

I have some rectangular map bitmaps, I have the lat/long of upper-left
and bottom-right. Iwant to make these into GeoTiffs that will work with
my GPS/PDA.

There must be a program that makes the geotiff metadata file from this
information, I cannot believe I have to calculate the distance accross
the map and scale this to the number of pixels to enter into the
ModelPixelScaleTag.

Does anyone know of a little util to do this?

Chris

On 11 Oct 2006 16:56:31 -0700, chrisaaaaa@googlemail.com wrote:



Your information is insufficient - you ned to know the projection of
the image. If you scanned a map it is very unlikely to use x =
longitude and y = latitude, as simply using latitude and longitude as
linear coordinates gives unacceptable distortions. EVen Mercators
projection, which uses axes the are parallel to latitude and longitude
is scalled differentially with latitude in a complex manner (I'm
afraid that this is a gross over-simplification!) The projection (and
there are very many possibilities) is one thing you need to know to
create the geotiff header. The other thing you need to know is the
datum - in other words, what spatial framework the map uses. GPS, for
example, uses WGS84, but maps may well use others, and the difference
is quite substantial in the context of GPS - up to several hundred
metres difference. Again, you need this information to create a
geotiff.

I understand there are utilities to create geotiff headers out there,
but you need a lot more information than just the lat,long coordinates
of the corner points of an image.

Paul

I can dig up the projection and datum, with this and the co-ordinates
of opposite corners do I have enough?

Chris

wrote:

chrisaaaaa@googlemail.com wrote:

Maybe GDAL can be of help? Check out gdal_translate and gdalwrap,
in that order, at http://www.gdal.org/gdal_utilities.html

Good luck,
Mattan

^^^^^^^^

gdalwarp instead. :-)


--
Tad McClellan
tadmc@augustmail.com
Fort Worth, Texas