Ok, we're in Autocad 2014 Civil 3D.
We have two inclined planes adjacent to each other but separated by a small gap.
What we would like to do is determine how those surfaces line up along their longitudinal axis.
Gotta hit the field but I'll check back and provide any additional info if needed.
I have an image of your question. It reminds me of two neighboring homes that are identical and the question is if the their roofs and walls line up with each other.
On a separate layer you could draw lines from the corners of the objects, along the top and bottom edge and at an array across the surface and even on diagonals across the surface.
Then you could intersect those lines on a perpendicular plane in the middle of the void area and see where and at what tolerance the opposing endpoints lie.
A perpendicular plane can also be placed at the end of each object to see the relation at those locations.
:-S
Would a baseline through the gap and xyz offsets to the baseline give what you need?
draw contours on the two inclined planes and include the gap between them
James
Turn off any rounding
I would create a volume surface between the two inclined planes. I would then shade the volume surface by elevation ranges: -X to -0.01' could be blue, -0.01' to +0.01' could be green, and +.01' to +X could red. This would show green at their axis of intersection.