View Full Version : Problem with the Coordinate Conversion
27th Jan 2012, 03:28 pm
I have a slight problem with converting one drawing from one coordinate system to another. Particular coordinate systems are Palestine 1923 (Clark 1880 Benoit) and UTM-WGS 1984, datum, Zone 37 North. I have coordinates for the points in the area of both coordinate systems, however when I try to convert these certain points (or line between points in this case) from one coordinate system to another, it does not make the conversion properly. It is not offset with few meters, it is completely off.
What I do basially is that I open one cad drawing which I know is in UTM coordinates, assign the right coordinate system (in this case UTM-WGS 1984 37N) to the drawing, save the file and exit. Then I open the next drawing of the same area, which has Palestine 1923 coordinates. Now I attach the previously saved drawing to the drawing opened at the moment and define a query, asking for location as “all” and query mode as “draw”. Then I execute the query, but what happens is that these points are completely off.
Does anyone have any idea what am I doing wrong here? I am almost 100% sure the point coordinates of the area are correct. Help is highly appreciated, lots of thanks in advance.
27th Jan 2012, 11:20 pm
Are you using Map3D or some other program?
28th Jan 2012, 12:51 am
Are you using Map3D or some other program?
Their profiles says "MAP3D 2011" ;) and by the steps they are using it sounds like it is MAP. So yes the thread needs to be moved to the MAP forum.
And No, I don't have an answer to fix the issue.
29th Jan 2012, 11:57 pm
Moved to the Map 3D (http://www.cadtutor.net/forum/forumdisplay.php?59-Map-3D) forum.
30th Jan 2012, 10:41 am
Please upload here those 2 maps, so we're gonna take a look at 'em, sir.
30th Jan 2012, 04:39 pm
What have described is all the right steps it seems to me. I have never had an issue with AutoCad Map 3D erring when doing what you have stated. However, it would be a good idea for you to start over with new files that have no coordinate system projections on them and go through the steps once again. This typically is an operator error rather than software error.
9th Feb 2012, 06:30 pm
Greetings everyone, thanks for the replys and sorry for not answering, as there were few other more urgent things.
Anyways I would still like to sort out what exactly is the cause of the conversation issues, is it either problem with wrong coordinates being submited to us or is it map3d that is not doing it correctly.
Anyways, situation is following, I have 4 quadrangular areas with 4 points, one is in Palestine 1923 on Clark 1880 ellipsoid (spheroid) and other is in UTM37N on WGS84 ellipsoid. These 2 areas are supposed to match 1 on 1 (altough in either coordinate system the area is supposed to be already in the beginning slightly different), but when I do my conversion from one system to another there is clear offset as seen on picture below. Conversion was done from palestine to UTM, but same thing happens when done opposite.
Polyline on the left is in UTM system as the one in the right is converted from palestine to UTM with a way that I described in the introduction of this thread.
I am also going to add the coordinates on here, so that maybe somebody can possibly check it with either map3d or any other possible map software in order to find out what exactly does not add up here. Lots of thanks in advance.
9th Feb 2012, 07:03 pm
You certainly have a conundrum to deal with. Map 3D has never given me erroneous output when doing conversions.
Is it possible for you to share you're files so we can take a look at them and try to replicate it?
I am wondering now if Map 3D may have a problem with the coordinate systems your using. I primarily work in U.S. State Plane systems. At times I will receive data that is UTM WGS and I have yet to have an issue with it.
17th Feb 2012, 10:09 am
I checked coordinate system properties with consultants, and it seems, that they match nicely, still they dont experience offset as i do. Coordinate system type is the same. Projection type matches, Northing and Easting False origin match, projection parameters match, therefore I am not sure exactly what might still cause the offset.
Can anyone possibly please comment the fact that when i look at the properties of the coordinate system type from the coordinate system manager, there is "tick" in front of the geodetic, but could it be possible, that the "tick" should be in front of non-geodetic system type? Would that make any difference? I guess it certainly would, however I also guess commonly it is still geodetic coordinate system type that is used in conversion, or am I wrong here?
Unfortunately I can not share files, because of the confidentiality. Lots of thanks in advance.
PS What our consultant also said, was that they also tried different softwares for conversion before finding the one that did the conversion correctly. Those softwares which also caused slight offset also had the same correct parameters as they were supposed to have, but for some reason they still did the wrong conversion.
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