Civil 3D Fundamentals: Surfaces from Contours

After Dana’s great post last week on pasting together surfaces to get a finished composite surface, imageand after this request for help today, I thought I’d actually write up something and work in a quick lesson on moving from elevated polyline to labeled C3D surface. No rocket science here, but a good fundamental in getting going with C3D.

So here are the givens: Polylines with elevations and a decent C3D template with some good surface and contour label styles. I’m going with the NCS Extended template.

Now, let’s get in to it after the jump!

Start by creating a new drawing from your template. Don’t do this in the drawing the imageaerial company sent you, it won’t have any styles! Once you have a nice blank drawing with a bunch of styles, insert the data files the aerial/city/engineer/architect/developer sent you. You know, the one with a bunch of polylines.  I like to explode them once on insert so that I don’t get too crazy with the explode and wind up with 100,000 lines instead of 10,000 polylines.

Now that you have a drawing full of elevated polylines, open up Prospector and expand to the Surfaces branch. Right-click on Surfaces and select Create Surface. Type in aimage name if you like, and change the Style as desired. I’m going to use a style that shows the border only to begin with, because I have 1 square mile of polylines in the demo set.  (BTW if you want to follow along at home, go buy the Mastering book here, I’m using the Aerial contours from Chapter 5.) Click OK to make your nice empty surface.

Expand your new surface in Prospector, expand the Definition, and right-click on Contours to select Add. Within the Add Contourimage Data dialog, add a description if you’d like, but generally leave these settings alone. They’re pretty dialed in for handling aerial contour data, and will give a pretty damn good surface without tweaking. If you really want to know what they all mean, click the Help button within the dialog to get right to the specific help. Click OK to proceed.

Use a crossing window to pick all the contour objects. If you’re being fast and lazy like me, just type ALL at the command line. C3D will ignore the text objects and process the polylines as contour point information. When it’s complete, you’ll see a border around the drawing indicating a surface was built. If you want to verify, simply pause over your drawing and see if you now have a tooltip indicating an elevation. If you like, turn on contours and you can see how tight the C3D generated contours are to the original data.

Now that you’ve added the data, you can freeze it to make it go away, imageor if you’re compulsive, you can erase it. If you erase it, you have to add the objects to the  surface definition first. To do this, right-click on your surface in Prospector and select Surface Properties. On the Definition tab, change the Copy Deleted Dependent Objects to Yes as shown here. Click OK, and erase to your heart’s content. For the record, I don’t really recommend this, it has a tendency to take longer than you’d think.

Now that you have just a surface border, change the surface style to something more presentable.image I’m using 2′ and 10′ contours since the style is built in to the template. Select Surfaces->Add Surface Labels->Add Surface Labels from the menus. Yes, you could pick the command we’re about to select directly, but it assumes you’ve set the styles prior. Not a normal thing for a newbie to have done.

Change the Label type to Contour – Multiple at Interval and change the styles as you need. I’m using Proposed Major and Proposed Minor labels direct from the template. Click the Add button and then pick a couple of points that will draw your first contour label line. Once you pick a second point, C3D will ask you for a Interval Along Contour at the command line. This is how often C3D is going to place a new little tick of a contour label line to place a contour label. On my scale, I’m going to use 500′

Repeat the process if you’d like to add more contour labels, but take a look around before you do, you might have enough. Here are a couple of shots of my surface before and after labeling. The decimal places are simply a matter of style.

image                     image

To make the contour label lines go away, select it, and right-click imageand pick “Select Similar.” Then right-click again and select “Properties.” Within the Autocad Properties, under the Civil 3D heading, toggle the value for  Display Contour Lines to False as shown.

That’s it. Surface built, contours applied, boss impressed. We hope you’re enjoying the reminders about these fundamental techniques. Let us know what you think should be next in the comments below!

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