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Thursday, February 19, 2009

Parking Lot Surface V

Using the TIN Triangle catches works great until a contour goes through it. As indicated in the picture below we can see that the contour is bending around the curve.

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The contour is bending around the curve because the surface was modeled with a straight grade from the BCR and ECR. The surface spot elevation label shows that the temp surface and the parking lot surface are not the same. The difference between the midpoint elevation of the Parking Surface and Temp Surface is not that large, but greatly changes the appearance of the contour. Depending on the length of the curve and the slopes of the parking lot the difference will be either greater or smaller than the one shown. To get rid of the curved contour we will need to add some PVI points to the curve to better approximate the grades of the parking lot. The number of PVI points is dependant on the length of the curve. The picture below shows the affect of adding a PVI at the midpoint.

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Both of the quarter points added.

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So we can see that the contour doesn't follow the curve and provides a nice straight contour.

Related Posts:
Parking Lot Surface I
Parking Lot Surface II
Parking Lot Surface III
Parking Lot Surface IV
Parking Lot Surface V

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