Surface From Contours

[Anonymous]

All,

I have a situation where i need to create a furface from contours that are simply PL. I was given a .DGN, i exported to a dwg, and copied the countours into a drawing. I need to create a surface from the contours. I created a surface, and used the defintion tab to add these lines as contours, and breaklines, both gave me crazy results. Are there any tips anyone has to accomplish this. I have attached the contours to use as an example of what i have to use. This seems like it would be a pretty common task.

[Anonymous]

It helps if you clean up the drawing in 3D view to avoid crazy results.

[Joe-Bouza]

you got some contours at bad elevations

[antoniovinci]

You could get rid of rubbish setting the view with the command: _-VIEW suboption _FRONT

[nilesh33]

Hi,

Some of your contour lines are at zero elevation. We need to asign elevations to them which are already stated in the text format on those contour lines.

Snap attached here with may help you to do the same.

[Anonymous]

So i have moved all the polylines to the correct elevation, and i still have a wierd situation. Some of the Arcs that have been turned into a PL have a - elevation even though when i use the ID command it says that is at the correct  Elevation. The wierd part is it seems to be mirroring the contours.

[Anonymous]

[rl_jackson]

You should look into using gradings, u then would only create one polyline of featureline with elevation and specifiy a target slope, distance or elevation

[nilesh33]

Hi martin,

Actually something wrong with these contours and i have fixed them in my file.

So replace them with following file and rebuild respective suface.

Attachment

[Jeff_M · Accepted solution]

Drawings converted from DGN's have always produced strange polylines. For whatever reason, most, if not all, of them have their Normal at (0 0 -1), with the X & Z values the inverse of what they should be to be translated correctly. Kind of difficult to explain, but if you LIST a known good polyline and compare that to the LIST'ing of one of these DGN generated polylines you should be able to see the difference.

 I have a lisp that fixes MOST of these plines with the -1 normal Z, although there are still some that trip it up. Of course, these doesn't fix those polylines that are at 0 elevation.

[Anonymous]

Thanks for all the input guys. I ended up using quick select to isolate all the negative values and just redrawing them by hand. Once all the countours were corrected the surface built smoothly. Ill have to look into building a lisp like yours Jeff.