Frage zu tif- und tfw-Dateien?

Question

<\/HEAD>Hallo!<\/P> Ich habe eine tif-Datei und (im selben Ordner) eine begleitende tfw-Datei, die die richtigen Koordinaten für die tif-Datei liefern soll. Aber wenn ich die tif-Datei in Arc-map öffne, werden die richtigen Koordinaten nicht angezeigt, tatsächlich ist das Bezugssystem "undefined". Wie bekomme ich das richtige Bezugssystem für meine tif-Datei? Ich bin neu bei Arc-map, daher wäre etwas Hilfe wunderbar!<\/P> <\/P> \/Pontus <\/P><\/BODY><\/HTML>

PontusAxén · Answer

Thank you all!

Great tips! The reference system was somehow wrong defined, but It's solved now!

/Pontus

MelitaKennedy · Answer

To expand on Chris' answer a little bit, a world file describes the cell size, any rotations, and the coordinates of the lower left corner of the raster. Here's an example from Wikipedia:

32.0

0.0

-32.0

691200.0

4576000.0

There's no information on the coordinate system, and it could be any UTM zone, a bunch of Gauss-Kruger zones, and probably a few other things. There's no way to know, unless the coordinate system is also defined in the TIFF, you have knowledge of the coordinate system, or can pick a likely coordinate system based on your knowledge of the location that the data represents.

Melita

ChrisDonohue__GISP · Answer

Besides the suggestion by Jake Skinner, I would check to see if the imagery actually already has a projection assigned.  Use ArcCatalog to check the properties. My guess given your symptoms is that it does not.  The world file( tfw) often only provides the correct location if it was already in the correct projection.  Since it likely has no projection....

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

Chris Donohue, GISP