I am using ArcGIS 10.3. A collegue in Asia georefferenced a .tif image for me using the ArcGIS georeferencing tool. He uses the same version of ArcGIS. Before rectifying he saved the link table. He send both, the link table and the georefferenced image. Trying to adjust some of the georeferencing, I opened the original image and imported the link table. After having imported the link table, the source points are about 2 km west and 2 km north of what they should be. I cannot figure out, why. My collegue and me both use the same coordinate system (WKID 32642, WGS_1984_UTM_zone42M). Does anybody know what could be the problem?
not a feet vs meters thing is it?
as far as I know map units are determined by the coordinate system selected so I would not be able to change these. Changing the display units obviously does not help or do you have something else in mind regarding the units?
The link table may have been made in the coordinate system of the map and not the data, hence, they could be different. Worth a check on the values of the link table and how the coordinates are defined and whether they are correct
thanks for your efford. I checked the .prj of the Link table and the data frame properties. Both are identical.
Data frame property
.prj of Link Table
WKID: 32642 Authority: EPSG
Linear Unit: Meter (1,0)
Geographic Coordinate System: GCS_WGS_1984
Angular Unit: Degree (0,0174532925199433)
Prime Meridian: Greenwich (0,0)
Semimajor Axis: 6378137,0
Semiminor Axis: 6356752,314245179
Inverse Flattening: 298,25722356
Unfortunatelly, this does not seem to be the problem.
What are the actual values of a location and for what location? 2 km is a big difference. 200m would suggest a datum difference, What other coordinate systems are used in your area? I have run out of ideas... what does your associate say?
These are some of the values from the link table. In Excell I calculated DX and DY. I find it noticable that the differences between X Source and X Map aswell as Y Source and Y Map are similar in magnitude to the error in the positioning of the map.
|X Source||Y Source||X Map||Y Map||DX||DY|
I have no more ideas, except to revisit the georeferencing. Sorry, the differences are too big to be something simple
after you had run out of ideas, I did no longer pursue this issue until today my collegue send a new link table which he used for georefencing a similar image. It looks like that:
9.543703 2.445142 444393.037816 4340604.876407
10.210346 4.964898 445233.124652 4343248.168412
11.711133 3.523411 446550.556075 4341673.463281
2.363828 7.071456 436840.989781 4345520.312199
10.966851 4.219995 445830.961943 4342445.428037
I can easiely recognize the map coordinates as the correct UTM coordinates. Yet, I do not understand what format the source coordinates are in. Source, target and data frame are set to WGS_1984_UTM_Zone_42N (WKID: 32642 Authority: EPSG). When I set source georeferencing points in the same project as my collegue, I get UTM coordinates. Do you or anybody else have any idea what could have let to the diverging coordinates system that the source coordinates are recorded in in my collegue's project? I am pretty sure that this is related to the original question of this thread.
P.S.: This is what the .prj file says:
the first two columns look like image coordinates unless you are referencing images near the equator and the Greenwich meridian