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Using Offset Points (Video)

Learn how to use offset points to designate linear high and low points on the optimized surface.

Important: The Elevation Offset grading object has been renamed to Offset Points in Grading Optimization. This video still refers to Elevation Offsets, though the concepts are still the same.

This video demonstrates:

  • Placement principles for Offset Points
  • Checking high and low points of Offset Points
  • Potential conflicting constraint awareness
  • Violation Result views

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Transcript

In Grading Optimization, Offset Point objects are polylines placed to control the elevation difference between two points along a surface. The order in which you sketch the Offset Point is important because the start of the line is the high point, and the end of the line is the low point. In this example, we want a range between 4 and 5 feet.

Exaggerate the elevations of this view to enhance the visible differences of the terrain elevations.

Notice the elevation at the high point is at 86.5 feet and at the low point is at 82.5 feet. The difference of four feet is within the range specified.

Note that Offset Points can cause conflicting constraints which cannot be resolved. For example, the Maximum Slope is set at 33 percent. If we then set more significant offsets such as 150 to 160 feet to this 387-foot-long line, the software will try to create a slope of more than 33 percent.

This conflict is best seen in the Violation View. Each of these triangles has a slope of more than 33 percent. As you can see in the Convergence Plot, the surface cannot be resolved within these constraints as the feasibility line has ceased to lower toward zero.

Again, to check the offset, the high point is at 135 feet and the low point is at 6 feet. With a difference of 129 feet which is as close as it can get to the specified range. Use Offset Points to constrain slope between grading objects and adjacent grades or other objects. Care should be taken to be aware of potential conflicts with global constraints or those of other grading objects.

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