new contours will not go straight

new contours will not go straight

Anonymous
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Message 1 of 9

new contours will not go straight

Anonymous
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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.

 

 

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Message 2 of 9

rkmcswain
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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.

R.K. McSwain     | CADpanacea | on twitter
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Message 3 of 9

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



Aren't the triangles made from the contours?


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Message 4 of 9

Todd_Rogers
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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...

 

2017-07-28_14-45-01.png

 

 

Todd Rogers
Civil Administration
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Message 5 of 9

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

TIN= Triangulated Irregular Network

Joe Bouza
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Message 6 of 9

Joe-Bouza
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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....

Joe Bouza
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Message 7 of 9

doni49
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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.


Don Ireland
Engineering Design Technician




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Message 8 of 9

wfberry
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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

 

 

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Message 9 of 9

BrianHailey
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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.

Brian J. Hailey, P.E.



GEI Consultants
My Civil 3D Blog

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