AutoCAD Civil 3D

[#1]

Hi everyone, 

They send me a file that has polylines as contours and when I try to do the surface adding contours an error appears saying that the breaklines couldn't be added because they crossed a breakline, I don't understand why. Any help would be greatly appreciated! 

[#2]

I'm confused. Are you adding them as contours or breaklines? You should not be getting this error if your adding them as contours. Is this a blank surface, or does it contain other data elements, like feature lines or breaklines?

[#3]

If any two polylines intersect you will get this error. You can modify the build options of the surface to allow crossing breaklines and then all contour polylines will be added.

Prospector tab of Toolspace, expand Surfaces, right click your surface, select Surface Properties. Go to the Definition tab, expand Build. Set Allow crossing breaklines to Yes.

[#4]

Hi,

I am new with Civil3D and I am having issues with creating a surface from polylines as well. I was given a topographic map with contours and the map scale was 1"=30'. So I converted the lines from the map to polylines, scaled them up and set their elevations to that for the contour lines. I also trimmed my map to include only the area I am interested in. Then I followed the instructions to create a surface from contour lines. I have a surface but the elevation range for the surface is (5700-6276ft) while the original contour lines are (475-525ft). Any idea why this might be happening and how I can deal with this?

I am using Civil 3D 2013. My end goal is to export the data to HEC-RAS to do hydraulic modeling.

Thanks!

[#5]

Scaling up the drawing I suspect? Was this a digitized paper map at 30 scale? It would be unusual for a cad drawing of a topo be drawn at something other than one to one world

[#6]

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ccoles wrote:

I'm confused. Are you adding them as contours or breaklines? You should not be getting this error if your adding them as contours. Is this a blank surface, or does it contain other data elements, like feature lines or breaklines?

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The ONLY difference between adding objects as breaklines vs. adding them as contours is when you add them as contours, you must weed and supliment them and you get the option to minimize flat areas. Other than that, they are exactly the same and you will get the message about breaklines crossing (assuming the contours cross each other).

[#7]

BrianHailey wrote:
Other than that, they are exactly the same

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Sorry B., but I think you should not let these words read to the young readers of this forum.

Even if contours and breaklines behave identically in Autocad, they are DEFINETELY different from the conceptual point of view: contours describe the raw surface of a terrain, while breaklines are put where that surface must stop because of a river, a road, and so on...

You cannot mix these two notions, that's my humble opinion.

[#8]

For the record.  I concur with Brian.

Bill

[#9]

@ sdhauban

It occurs to me that your elevations are off by a factor of 12.  I suggest looking into the units settings in your drawing; something is in inches that needs to be feet, or vice versa.

[#10]

Thank you all! antoniovinci thank you for the clarification.

troma, it might be some unit error. I went back and checked, the units in my Drawing Setting is set to Feets. In the Drawing Units window I had Inches as my units. I changed that to feets and updated my surface but it still gives me the same values. I'll keep looking into the units and see if I can figure this out.