Contents   Index

Adjustment Weighting

The cadastral adjustment applies weighting to all bearings and distances in the data. There are six levels of accuracy as follows:
Accuracy SD Bearings(Secs) SD Distances PPM (Metres)
1 5" 0.001 5
2 30" 0.010 25
3 60" 0.020 50
4 120" 0.050 125
5 300" 0.200 125
6 3600" 1.000 1000
7 unknown accuracy excluded from adjustment

Initial values are set according to the date as follows:
Accuracy Date Range
2 After 1980
3 1908 - 1980
4 1881 - 1907
5 Before 1881
Line type 995 (usually used for a direct connection to a control point.) is held at an accuracy one beeter than its Parcel accuracy.

Processing Old Files
As there was no accuracy variable available in the DOS version of the software, the lot type and line type was used to override the default accuracy. When these files are read in to GeoCadastre, the old rules for setting accuracies are used to explicitly set each parcel and line accuracy, and the lot and line types are stripped of the extra data.
The old rules were as follows:
Compiled plans were flagged by setting their lot type to be 16 to force them into accuracy 5, or to lot type 17 for accuracy 6.

The default lot accuracy could also be overridden by adding a multiple of 1000 to the lot type as follows:
Accuracy Date Range Lot Type Line Type
1 N/A 2000 - 2999 995
2 After 1980 3000 - 3999 N/A
3 1908 - 1980 4000 - 4999 N/A
4 1881 - 1907 5000 - 5999 N/A
5 Before 1881 6000 - 6999 N/A
6 N/A 8000 - 8999 N/A


By adding the appropriate value to the original lot type the accuracy indicator could be included and the original lot type maintained.

For example a lot coded 2997 would be an unclosed traverse of accuracy 1.

To cater for compiled plans whose dimensions may be based on a much older survey and for partially compiled plans where only some lines were surveyed, 800 was added to the line type to indicate that its accuracy should adopt the accuracy according to the date of the plan.

Old jobs are now converted as they are read in according to the following rules: