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What are the limitations (if any) of conducting and edit session on a feature data set that has a defenition query applied to it?
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10-19-2011
06:15 AM
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Hi Melita, I did adjust the false easting by the amount the points were off from target points and had a very good fit. Saved .prj file for future use. Used new .prj file to assess 7 other points I had with coordinates in both systems. Once completed I calculated geometry of points and found only 3 points were out by 1 mm. Thanks for your help. Hi Mark, Perhaps some confusion on the data I posted. The first post was under the assumption of doing a 'Custom Coordinate Transformation' where I had assigned a projection and datum to the local grid. Where in fact this was inncorrect. The following is what I have. Local Grid - No Projection or Datum UTM Grid - False Easting 500,000 - False Northing 0 - CM -105 - SF: 0.9996000 - Lat of Origin: 0 - Linear Unit: Meters - GCS: NAD 83 - Datum: NAD 83 - Spheroid: GRS 80 From the coordinate pairs I have (3) I calculated the tranformation parameters using a two-dimensional conformal transformation, and they are: East Translation: -495745.892m North Translation: -5717240.125m Z Translation: None (no elevations for either points) X and Y rotation: None (Both grids have same north orientation) Scale Factor: 1.000477 What Melita requested I do was to apply the transformation parameters to a custom projection. First the false eastings and northings had to be adjusted so each grid had coincidental grid origin. Since the false easting of the UTM was 500,000 the East Translation needs to be adjusted, thus 500,000 - 495,745.892 = 4254.108. Melita also suggested I multiply the false east/north by the scale factor, in this case it is not necessary,I took care of this in my Conformal transformation parameter calculations. I am not sure if this will help you any. It did solve my problem with this particular situation but I am faced with many other transformations that have a rotation. I had originally intended to do the transformation with Arc 'Create Custom Geographic Transformation'. The problem with this is that you need a GRS in the Local grid wich I do not have and I also need the transformation parameters for the rotation. Arc does not seem to offer any help on this. I hope this clears up some issue.
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09-26-2011
01:37 PM
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Melita, Your solution did help somewhat but also posed a few more questions. Following the steps outlined I did get the points to almost align. Without adjusting the False Easting/Norhting the UTM points are all West of there intended point by a consistant 238.500m. Adjusting the Easting only, points are out 236.471. by adjusting both the East/North the UTM points are out 2700m almost due North. My second question is that I would like to convert all of our UTM datasets into the Local Grid with a custom projection, the help menus are a little vague on how this is done, any suggestions. Thank You so much Scott H
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09-22-2011
12:42 PM
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Operating system is Windows 7 Pro and the ArcGIS version is 10.0 I am trying to create a coordinate transformation from UTM Z13 to a Local Grid. I have established the local grid system with the following: Projection: Transverse Mercator False Easting: 500,000 False Northing: 0 Central Meridian: -105 Scale Factor: 0.9996000 Lat. of origin: 0 Linear unit: meters GCS: WGS 1984 Datum: WGS 1984 Spheroid: WGS 1984 I am using coordinates in UTM Z13 with the following: Projection: Transverse Mercator False Easting: 500,000 False Northing: 0 Central Meridian: -105 Scale Factor: 0.9996000 Lat. of origin: 0 Linear unit: meters GCS: NAD 83 Datum: NAD 83 Spheroid: GRS 80 I have calculated the parameters from known points in both coordinate systems to be: East translation: -495745.892m North translation: -5717240.125m Z translation: None X, Y rotation: 0 (none) both systems have the identical north orientation Scale factor: 1.000477 Local grid is slightly larger than the UTM I have managed to get the .gtf file to work in 'project' but it appears the new translated points are only about half way to where they should be (about half of the East and West translation). I have done this by using the 'position vector' method. I also do not know what value to enter in the 'scale differance (ppm)'. Any help you can offer Nobbir would be appreciated. Scott
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09-21-2011
02:54 PM
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I am trying to create a custom transformation to convert UTM Z13 coordinates to a local grid. I have created a .gdf file with the correct transformation parameters and have it stored in the correct location. When I use the 'Project' tool I am not given access to the 'Geographic Transformation' method drop down box. I am assuming this is where the .gdf is accessed to perform the tranformation. Any ideas on this? Scott
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09-21-2011
08:56 AM
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