I think it would be beneficial to have a right click option when elevating that would allow the user to click two points, apply elevation ( or pull elevation if there is elevation at the points) and and use this temporary line to pull an elevation.
Not sure I really understand here Pat - You have the Contours and you say that they are defining a Plane - well if that is the case - you can use the contours to elevate the line - OK in the corner the contours change shape - so there is no plane there - are you saying that that is what you want to change? If so then elevate the line where you have contours and then elevate that point using Edit Linestring, Vertical - Inbound or Outbound Slope along the line - selecting the slope of the line between 2x contour elevated points where the contours do form a Plane with the corner point where you have a spot elevation - that should work and be pretty straight forward
Am I missing something here?
Hopefully this is more clear.
The enclosed Video shows you how to do this in current software - you do get a Point to Point Verticval Angle calculator in Slope Fields - so if you Edit the Linestring, and then select the location for the VPI and then use Incoming or Outgoing Slope (depending on which controls the elevations based on the direction of the line, you do then get the 2 point snap on Right Click when determining the slope value to compute the elevation from your spot grade points - The video below shows how.
Hope this helps
Retrieving data ...