Duplicate Point Numbers - n-0.9, n-1

[mdhutchinson]

I have a control point file that has duplicate point numbers (see below)

They are PCR - PCM pairs... they appear quite close to each other like around 2 inches.

When running GTPS_IMPORTPTS ... point layout modifies the initial point to n.1

So, for instance the first two points are PCR-1 and PCM-1... APL appears to be bring the second point as PCM-0.9.

Is this how APL deals with duplicate numbers in control point files?

Any idea what significance PCR and PCM has?

Points,Northing,Easting,Elevation
PCR-1,319298.0878,1714177.6780,1131.1224
PCM-1,319297.8770,1714177.4880,1132.1492
PCR-2,319231.0712,1715085.2430,1157.9058
PCM-2,319230.9431,1715085.4940,1158.9113
PCR-3,319687.0000,1715068.9680,1154.4948
PCM-3,319687.0217,1715069.2380,1155.5401
PCR-4,319991.1841,1715058.3140,1148.2740
PCM-4,319991.3186,1715058.5440,1149.3050
PCR-5,319878.0516,1714803.8980,1133.4969
PCM-5,319878.3073,1714803.9180,1134.5309
PCR-7,320198.2642,1714169.2990,1136.3792
PCM-7,320198.4728,1714169.1150,1137.4092
PCR-8,319621.8033,1713893.5000,1116.7126
PCM-8,319621.7307,1713893.2300,1117.7731

[s.hamel · Accepted solution]

Correct, it is attempting to avoid duplicate point #'s prior to import, and unfortunately does not take into account the prefix when doing so.  As well, when a duplicate is found it will add .1 in order to avoid the duplicate, which doesn't work well in this case since they are negative numbers.

So that being said, next release will take into account the prefix, so these would not be considered dupes, as well it will handle negatives appropriately so it would end up being -1.1 instead of -.9 in your current case.

As for the PCR vs PCM, I can only guess since these are done by your surveyor I am assuming, visually they appear to be a very minor offset on the coordinates so may denote one of these two scenarios:

1.  One is International feet vs US survey feet, which will result in very minor differences in the coordinates on large coordinate systems like state plane

2.  One is original placement of the control and the other is current locations based on a re-survey.

Again, utter guesses, you will need to ask your surveyor.

Thanks,

Shayne Hamel