This app will generate grade diagrams at points on Autodesk® Civil 3D® tin surfaces, visualizing the possible directions where the grades fall within a specified range.
It aids the civil designer during the initial alignment/route selection process on any sort of linear structure (road, canal, pipeline, etc) where the design criteria impose restrictions on the min/max allowable grades. By chaining a series of diagrams together, a first draft alignment with the desired properties can be constructed.

Upon initial invocation, the app will ask the user to pick a tin surface, specify minimum and maximum grades and input a segment/leg distance. Once these parameters are defined, the app will compute and dynamically draw the grade diagram at any point on the surface.

Grade diagram computation:

• the input point is projected to the surface to obtain an elevation
• a total of n points is sampled on the surface around the perimeter of the input point at a distance d, where the n is the number of envelope points and d is the segment distance
• grades are computed from the center point to point i
• a line is drawn from the center point to point I on the perimeter if the Abs of grade is less than the max grade
• an envelope correction distance is computed for every point I and all points along the perimeter are projected to the surface and connected to form a 3d polyline (the diagram envelope)

Please refer to the complete app documentation and the attached images for more details