Crazy contour lines from imported point cloud

[Anonymous]

I'm having some trouble creating a decent looking contour map of an interior slab that was scanned with a LIDAR scanner.  I have imported my point cloud (RCS) and created a surface in Civil 3d, but the TIN is very hectic and the contours are even more so.  Does anyone have a workflow for something like this?

In the past I've taken elevations with a zip level and created a surface over existing plans and manually added the elevations to create a contour map of sorts, but if I can find a way to use our scanner, I could get a lot more data and a much more accurate map.  

[Anonymous]

Can you thin out the data? What happens if you increase the contour interval? Maybe spot elevations on a grid would be more useful?

In really flat and level areas contours tend to wander all over.

[TerryDotson]

In the event the point cloud contains other points (besides the slab) are you limiting the results to the proper classification?  For example decorative tree points, etc.

[Anonymous]

A grid of points over the point cloud might work.  Do you know of any tutorials for that kind of thing?  I'm new to Civil 3d and I'm still learning the ropes.  

I'll try increasing the contour interval in the meantime, and I'll try simplifying the surface, but I don't know how that will affect the data.  I'd rather control point extraction with a grid.

Thanks

[Anonymous]

To create a grid of points whose elevations are derived from the point cloud surface, Home tab>Create Ground Data>Points (expand by pulling arrow down), Create Points - Surface>On Grid

The routine is fairly simple - it wants to know X & Y spacing and the orientation of the grid.

You can label spot elevations similarly: Annotate>Labels & Tables>Add labels. In the dialog that opens select Surface as the Feature and you'll find Spot Elevations on Grid in the Label Types. It again asks for X, Y and orientation (I think, it has been a while).

[Anonymous]

By the way, if you set points on a grid you would then create a new surface using just those points. Hopefully it will work.