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COGO distortion

Question asked by shyulove on Mar 11, 2015
Latest reply on May 1, 2015 by jmward

'm trying to input a road center line using COGO, I don't have any experience using the COGO toolbar on any ArcGIS version. I'm currently using ArcGIS desktop 10.2. The road project is roughly 6 miles long with many curves. 

My first attempt resulted in a line that is very distorted and far away from the road on the imagery. After reading more about ESRI's COGO ground to grid correction (ArcGIS Help 10.2 - About applying ground to grid correction) and adding the convergence angle and scale factor, the resulting line is still roughly 200 + feet away from the road on the imagery.

The dataframe is set up for NAD83 HARN State Plane WA South. I also took it a step further and reprojected the NAIP imagery to the same CRS as the dataframe. I agree, I think is a convergence angle issue. The plans don't have convergence angle or scale factor information. I forgot to mention that I'm using the convergence angle and scale factor from a near by survey control point from NOAA's NGS.

 

My questions are:

  1. is this kind of distortion normal?
  2. if so, how do you fix this?
  3. I'm thinking now I could use the Spatial Adjustment toolbar to move the cyan line and place it over the road. Is this an acceptable practice?

The blue line represents my first attempt and the purple line is my 2nd attempt. You can see that the purple line is closer to the actual road on the imagery.


COGO Center line.jpg

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