topic Re: new contours will not go straight in Civil 3D Forum

new contours will not go straight

Anonymous — Fri, 28 Jul 2017 18:34:29 GMT

I have a new surface made from a corridor and they are not straight across the road. my road has a 2% cross slope. I can only get straight lines if I do a 0% cross slope.

Re: new contours will not go straight

rkmcswain — Fri, 28 Jul 2017 19:24:09 GMT

Turn on your triangles and see what is going on.

Contour lines are simply connecting like elevations on the triangles. Bad triangles will give you bad contours.

Re: new contours will not go straight

Anonymous — Fri, 28 Jul 2017 19:26:16 GMT

How do you know you have bad triangles and how would you fix them?

Aren't the triangles made from the contours?

Re: new contours will not go straight

Todd_Rogers — Fri, 28 Jul 2017 19:46:15 GMT

Depending on which surface you used (top or bottom (datum)), you need to apply Overhang Correction. If the Top, then Top Links. If the Datum, then Bottom Links...

Re: new contours will not go straight

Joe-Bouza — Sat, 29 Jul 2017 01:31:48 GMT

NO
The elevation data you feed the surface is "Triangulated" . The contours are interpolated along the triangles.

TIN= Triangulated Irregular Network

Re: new contours will not go straight

Joe-Bouza — Sat, 29 Jul 2017 02:17:49 GMT

The contours are the visible expression of the triangles if they look bad doesn't really mean the triangle are. You need to compare your data with the results.

Also, what other possible data is in the definition.

Occasionally triangle may not go where you wish due to conflicts in data: missing feature line, blown elevation, wrong links used in corr surf, data you did not intend to add to the definition....

Re: new contours will not go straight

doni49 — Sat, 29 Jul 2017 04:59:17 GMT

Based on the limited info we have so far, my first thought is that under the surface tab in the corridor properties, you haven't turned on use as breaklines.

Re: new contours will not go straight

wfberry — Sat, 29 Jul 2017 13:49:53 GMT

Aren't the triangles made from the contours?

NO! If you ever had the "opportunity" to draw contours by hand it would help your thinking.

Do this--> take a handful of points and plot them out. Draw lines between each point and see they end up being triangles. Calculate where the EVEN contour will pass through these lines and you can see why they are not straight.

Bill

Re: new contours will not go straight

BrianHailey — Sun, 30 Jul 2017 03:13:41 GMT

My first guess is you've added too much data to your surface. What links/featurelines did you add from your corridor to the surface?

Remember, a surface can't have more than one elevation at any point. This means at the edge of asphalt, you can't have a surface that has the elevation of the edge of asphalt and one for the base course at the edge of asphalt.