I realized that I never got back to the list with the responses I received to my question regarding COGO (Sept). Original questions:
I have a encountered a couple of issues while doing COGO input from surveys.
1. Curve data that includes Length-Radius- and delta, but no curve direction. I was never good at, nor do I remember, trig.
2. Bearings that need to be adjusted for declination. I can get the declination from the NGDC/NOAA website, but converting individual entries is a problem/pain.
Any suggestions on how to deal with these situations would be appreciated.
I'm using 9.3 with the Edit Tools COGO routine.
I received the following responses:
Patrick Ladd:
I think problem 1 can be solved with the Curve Calculator on the COGO toolbar:
Inline image 1
Inline image 2
PATRICK LADD
Unfortun ately, my licen se does not include ARCGIS CO GO.
Also from Pa trick:
Now that I think about it, will problem 2 be solved under on the Editor toolbar dropdown Editor > Options > Units and check the Ground to Grid Correction:
Inline image 1
This does not work when I'm using the Edit tools COGO input routine. Works well if I'm inputting directly using Edit.
From Mark Goetz:
For the curves you can try to enter them as being tangent, though that certainly may not end up working. Regardless, start at the end if the curve than run the COGO to the other end, then by a tangent curve to complete. If it closes within reason then your good. If not, then you need to end the COGO just before the curve and simply enter a curve with the appropriate radius. You really can't "solve" these curve issues without all of the appropriate parameters.
As for the declination, I would skip the whole declination table approach and work off rotating the completed surveys based on line of occupation such as stone walls identifiable in available orthos or other basemapping.
From Liz Crutcher:
http://gisobsessed.blogspot.com/2010/03/cogo-made-easy-in-arcgis-desktop.html
Hi Ken, I found this article useful if you have not already come across it. I haven’t done in a while so not sure I can help you specifically.
Liz
This was interesting and helpful.
From Eric Belt:
1. When I go around a parcel, the curve direction (left or right) is the direction I would turn if I were walking along that line in the direction I have decided to go. Many times there will be segments that are specified in the counter direction to how you have chosen. Just swap north & south and east & west to correct this. (example: n07-34-16w would become s07-34-16e to change the direction 180 deg.)
2. I frequently find that the north reference used by the surveyor has no basis in the real world. I just go ahead and draw the parcel, do my closure check, and convert the lines to a polygon before rotating the whole thing the proper amount. That sometimes requires an eyeball on features in the aerial photos to approximate the alignment unless you can match it to an adjoining parcel.
I've also had occasion to use the rotation routine suggested by Mark and Eric.
Thanks to all of you.
Ken Geisler
120 Vista Way, Bloomfield, CT 06002
860-243-1166 (H)
860-280-8791 (C)
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