This COGO tool allows you to compute the offset of one point at a time or multiple points, displaying the offset distance and bearing/azimuth right in the dialog box.
If you access this routine from the Traverse View or Points Manager, the highlighted point becomes the offset point, saving you keystrokes.
If you access this routine from the Drawing View, TPC evaluates the drawing object you selected. If that object references a survey point, that survey point becomes the offset point.
TPC does not automatically preset the line used in this dialog when you access it from a view because it uses the selected data to preset the offset point.
Compute Offsets For Single Points
For single point offsets, you can also save the point on the line from which the offset distance is computed.
•Enter From point and Bearing in the 'Line to Compute Offset To' box to define an straight line you want to offset to. Remember that you can enter an equation for a bearing or azimuth (i.e., enter 11..12 to recall the bearing or azimuth between points 11 and 12).
•You can also pick a line from the current drawing [>>] or enter the end point of a line in the To field. This tells TPC to create the POL on an existing survey line.
•Enter the Point of Offset. The dialog box will display the bearing/azimuth and distance to the point on line (POL).
•To save the POL, enter a point label for it and choose Save.
•When you are finished, choose Close.
•You can enter as many Points of Offsets as you want, saving each computed point before closing the dialog.
Compute Offsets from Multiple Points
In the Offset to Line dialog, use the What list to select the multiple points you want to computed offsets from. That section of the dialog has its own controls for viewing and reporting the multiple offsets.
Offset to Survey Line
If you are not using geodetic distance and direction types and you recall an existing survey line, TPC will compute the offset to that existing line, regardless of whether it is a tangent, curve or spiral.
Use the From and To fields in the 'Line to Compute Offset To' box to specify the endpoints of the existing line or select it in the current drawing using the Line >> button. Once computed, the Offset and 'Distance from start of line' information displayed in the dialog will reference the arc of the referenced curve or spiral.
The Summary also clearly indicates that the offset is to a survey line and provides information about that line in the report view.
Offset to an Azimuth Line
If you recall just the From point and not the To point in the 'Line to Compute Offset To' box, TPC projects an azimuth through the From point and creates the offset to that azimuth.
This also happens automatically if you use geodetic distance and direction types. Intersections of geodesics are not well defined and probably not what you are interested in when offsetting to a line.
Offset to a Geodetic / PLSS Line
When you open the Offset to Line dialog, you will have an option to compute offsets to a latitudinal arc.
If the arc you specify is East-West, TPC uses it's PLSS computations to compute the offset per the 2009 BLM Manual of Survey.
If you specify a North-South line, TPC does a bearing-bearing intersect, but applies convergence to the intersecting bearing. This provides a reasonable approximation for an offset to a meridian.
