autocad question

[mikeh]

We recieved a set of contours from a city, all with z coordinates, all on the same layer, no text or labels. They are all 2 foot contours. I need to extract out all the ten foot contours. Anyone have a lisp or something that will extract out and relayer the tens? Or suggestions on where to search? I'm hitting the cad sites but not coming up with anything.
Thanks.
mh

[schroeder]

Do you have Autocad Map? If so, a query could do this pretty easily to find all contours where Z=0,10,20,30,40,etc.

Alternatively, isolate the layer and use qselect. Tell it you want to select polylines on the contour layer where elevation = 10. Then place these on a new layer and do it again to select those that = 20, etc. This might be slow, but I don't think qselect lets you use multiple values in the selection query (like = 20, 30, 40)

Andrew

[mikeh]

we have acad map. The countours range over 1000 feet. I'm looking for a less time consuming method, if it's possible.
mh

[schroeder]

Hmm.. I just looked into it and it seems that map doesn't want to query multiple elevation values in one go.

If you have LDD or Civil3D, create a surface using the existing contours, and then create a new set of contours at 10' intervals based on the new surface. Export these to a new file and away you go. This should be quite fast provided you've got the software. Accurate too, since you're not asking it to interpolate anything, just cutting contours based on the same input data.

[mikeh]

i tried the method of creating a surface model and extracting tens from there but the contours were too sloppy to use. Running out of time, i used the acad map method of "query" to get the tens...it went faster than anticipated. Thanks for the help.
mh

[dellis]

Export the surface into MAX and make the contours there using the section shape object and the array tool. You'll most likely have to weld some verts but it should work...then you could do whatever you want with the splines.

[mikeh]

Export the surface into MAX and make the contours there using the section shape object and the array tool. You'll most likely have to weld some verts but it should work...then you could do whatever you want with the splines.

getting huge surface models into max is trouble enough. When they get big, i have to chop them up and import them in sections. Takes forever. (Actually i was unaware that max could generate contours from models. Does it give you options about which contours you want? IE, tens vs twos or ones?)Realistically i can't see myself ever using max to get contours. Acad map works so easy and fast compared to making the conversion to max....which also entails moving everything to zero zero coordinates before import to max.
Mh