I am doing a pool grading plan and know full well I could have used available topo, which overlays the orthorectified photography, but I GPSed it Thursday none the less.
Last night I split both my observations and submitted them. My westerly point came back with the comment "Your station is 0.2 KM outside the polygon enclosing the reference stations" but my easterly point was OK. I checked my field traverse and the westerly point is 218.85m from the easterly point, the street runs 10° from EW.
Today I resubmitted, requesting 2 CORS to the West. The first requested CORS was 1 KM farther than the closest CORS and for whatever reason it was not chosen last night. The second was 1 KM farther than the farthest automatic CORS selection, but at 79 KM there is little to complain about anyway. Positions moved by 1mm and 2 mm respectively and RMS dropped from 4mm to 5mm. Traverse distance monument to monument is 717.346', adjusted and scaled distance from my post processing was 717.330'. I post processed to get L1 coordinates and elevations on 2 lot markers. Had I used my independant CORS coordinates I would have been "balls on" after scaling. A quick check of elevations field work to GPS shows nothing out by more than 0.02'. I have yet to create contours and compare them to the available raster file.
Life is very good when you have more than a dozen CORS within 100 KM of your work.
Paul in PA
