I used GCP derived from and than attached to a scanned UTM map to create a GeoTIFF with geo-coding information (basis for georeferencing satellite data later).
Everything worked well, but the result is not matching the utm coordinates I used, it seems like the output shifted, did I maybe misunderstood the input format?

Input GCP_1:
Name X Y Lon Lat Delta Lon
gcp_1 1.0 1.0 -1.30663 12.35663 0.0013325214
(1°30'.. W 12°35'.." N !)

Output geoinformation for GCP_1:
Table of used GCPs:
Number Label X Y Latitude Longitude
0 GCP 1 3.5 0.5 1°18'24" W 12°21'24" N

Thanks!

Dear Marco,

Thanks for replying and kind assistance. I´m quite not sure, if it was just caused by the different pixels (wrong pasting).
For me it seems the scene is to much shifted, or do you think I have to expect this and in reality it does not harm this much?!

Other methods gave same results? Is the algorithm somewhere availabe? Or can re-manipulate the information via an editor maybe?

Just have a look:

Input GCP:
# BEAM GCP export table
#
# Product: Loumbila_UTM
# Created on: Wed Nov 18 21:46:20 CET 2009

Name X Y Lon Lat Delta Lon Delta Lat Label Desc
gcp_1 3.5 0.5 -1.3066207 12.351392 0.0 0.0 GCP 1
gcp_2 9.5 716.5 -1.3066207 12.301382 0.0 0.0 GCP 2
gcp_3 713.5 713.5 -1.256717 12.301382 0.0 0.0 GCP 3

Output GeoTIFF (see the coordinates now below in table of used GCP!!):
Center latitude: 12°18'27" N
Center longitude: 1°15'24" W
Upper left latitude: 12°21'05" N
Upper left longitude: 1°18'25" W
Upper right latitude: 12°21'03" N
Upper right longitude: 1°12'21" W
Lower left latitude: 12°15'51" N
Lower left longitude: 1°18'27" W
Lower right latitude: 12°15'50" N
Lower right longitude: 1°12'24" W

The product uses a geo-coding which is based on ground control points (GCPs).
Number Of GCPs: 3
Function: Linear Polynomial
Datum: WGS-84
Latitude RMSE: 2.8910522083636145E-15
Longitude RMSE: 1.4204804482646359E-15

Table of used GCPs:
Number Label X Y Latitude Longitude
0 GCP 1 3.5 0.5 12°21'05" N 1°18'24" W
1 GCP 2 9.5 716.5 12°18'05" N 1°18'24" W
2 GCP 3 713.5 713.5 12°18'05" N 1°15'24" W
---------------------

I guess now, the mistake is caused by my input data:

Lon: 1 degree 30 (min) 663 (????? Seconds? Meters?)
Lat: 12 degree 35 (min) 1393 (????? Seconds? Meters?)

I guess I have to use as input decimal degrees? Could that be the failure?!??

Thanks, but my problem now this one:

My input data

# BEAM GCP export table
#
# Product: Loumbila_UTM
# Created on: Fri Nov 20 19:27:12 CET 2009
----------------------------------------------------------
Name X Y Lon Lat Delta Lon l Desc
gcp_1 1.0 3.5 -1.68417 12.97 0.0 0.0 GCP 1
gcp_2 9.5 716.5 -1.68417 12.883889 0.0 0.0 GCP 2
gcp_3 713.5 713.5 -1.60333 12.88389 0.0 0.0 GCP 3
------------------------------------------------------------
Beispiel UTM gcp_1 -1 30.663 12 35.1382

!!!! as input for the data above, comparing the output of georeferencing and projection, seems
quite heavy out of direction (expected Center in an range about Latitude 12 32 00 and Longitude 1 25 00????

Compare result of beam:

Center latitude: 12°53'41" N
Center longitude: 1°36'12" W
Upper left latitude: 12°58'14" N
Upper left longitude: 1°41'06" W
Upper right latitude: 12°58'10" N
Upper right longitude: 1°31'15" W
Lower left latitude: 12°49'11" N
Lower left longitude: 1°41'09" W
Lower right latitude: 12°49'08" N
Lower right longitude: 1°31'18" W


The product uses a map-projection based geo-coding.

Projection: UTM Zone 30
Projection parameters:
semi_major : 6378137.0 meter
semi_minor : 6356752.3 meter
latitude_of_origin : 0.0 degree
central_meridian : -3.0 degree
scale_factor : 0.9996
false_easting : 500000.0 meter
false_northing : 0.0 meter

Model CRS Name: EPSG:WGS 72 / UTM zone 30N
Model CRS WKT:
PROJCS["WGS 72 / UTM zone 30N",
GEOGCS["WGS 72",
DATUM["World Geodetic System 1972",
SPHEROID["WGS 72", 6378135.0, 298.26, AUTHORITY["EPSG","7043"]],
TOWGS84[0.0, 0.0, 4.5, 0.0, 0.0, 0.554, 0.045171992568114105],
AUTHORITY["EPSG","6322"]],
PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
UNIT["degree", 0.017453292519943295],
AXIS["Geodetic latitude", NORTH],
AXIS["Geodetic longitude", EAST],
AUTHORITY["EPSG","4322"]],
PROJECTION["Transverse Mercator", AUTHORITY["EPSG","9807"]],
PARAMETER["central_meridian", -3.0],
PARAMETER["latitude_of_origin", 0.0],
PARAMETER["scale_factor", 0.9996],
PARAMETER["false_easting", 500000.0],
PARAMETER["false_northing", 0.0],
UNIT["m", 1.0],
AXIS["Easting", EAST],
AXIS["Northing", NORTH],
AUTHORITY["EPSG","32230"]]

Output parameters:
Datum: WGS-84
Reference pixel X: 712.5
Reference pixel Y: 666.0
Orientation: 0.0 degree
Northing: 1425899.6 meter
Easting: 651535.3 meter
Pixel size X: 12.522428 meter
Pixel size Y: 12.522428 meter

Sorry, it seems not to be solved yet!

Best wishes

Timo

Thanks for your kind assistance!

Despite of the reprojection problem in UTM the lat/lon coordinates seems to match quite well. I guess I involved also a problem by myself in handling input data not accurate and I will try to improve my results including your advices.

Additional:
I solved some issues with my input data and now I´ve got acceptable results!