Hi,
I know that it probably old story, however I didn't find an answer.
Is there way to create centerline from buffer or polygon in Civil 3D?
There is should be some easy method to do it.
By now the only proper way is to explode object, delete lines that are smaller than minimum and do offset for merged border.
Any ideas?
Thanks
I honestly don't know what you are trying to accomplish. Perhaps you could provide a drawing or an image showing what it is you are trying to do.
When I think of buffer, I think of an area around something. Is that what you mean by a buffer?
I'm sure youre license is Civil 3D, but your question is a Map question, right? Perhaps posting in the AutoCAD Map group would yield better results.
The thing is that I have shapefile of 60m corridor along transmission line 120 km long. I need to extract centerline from it. Of course I can do it manually, but it's 120km. I've tried to explode shapefile and delete short lines that was on rounded corners and then extend the rest. However, I realize that even this could take hours and also it's not a beautiful way to do it. I know it could be done in ArcGIS by Collapse Dual Lines To Centerline, but I believe it could be done in AutoCAD.
I've also tried to create best fit alignment. It freeze my computer every time.
I'll upload picture tomorrow morning.
ps. I think this case could be applicable both to Civil 3D and Map 3D because everyone works with shapefiles.
Thanks!
I'm taking a bit of a guess as to what the OP is trying to do but - given a polygon like this one how would you accurately recreate the original centerline? Some parts of it are easy, but not all.
That's my understanding of the question as well
Not overly familiar with shapefiles but If the shapefile was exploded into CAD line primitives, would using JOIN not create a polyline that could be offset 60m?
neilyj (No connection with Autodesk other than using the products in the real world)
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Hi,
You understand it right. Here couple screenshots of shapefile.
Shapefile has 3638 vertexes! However, most of them are not important because was made by feature buffer command (my guess). Also explode method was just a try to get centerline. I can use offset, but as a result will get polyline with extra 1800 vertexes!
Hi,
>> The thing is that I have shapefile of 60m corridor along transmission line 120 km long.
>> I need to extract centerline from it
I would:
Does that help?
- alfred -
It would work but it will take hours cause offset works only with ONE object. However, it is only way so far.
It will be easer to query lines that are 10m and less for example, delete them, do offset for the rest and do extend for missing parts.
I believe that there is should be some proper and beautiful way how to do it.
Hi,
>> It would work but it will take hours cause offset works only with ONE object
I thought you have ONE corridor? Then you would only have one _OFFSET-command.
BTW: the most easiest way would be to get the source of the buffer, at least look to backups because there was an element from which the buffer were created.
- alfred -
The Join and Weed Feature Line command or Mapclean can be used to get rid of most of those verticies and make a single pline. If you do this the offsetting and other operationsshould perform much better.
John Mayo
If these operations take too long or dog the machine down, then perform the operations on small portions of the buffer. Working with segements of the data will speed you up and you can join the segements together to finish.
John Mayo
Another method maybe.
1. Create a surface based on sides of ROW.
2. Create contour lines.
3. Extract contour lines.
4. Find proper one.
It could be very good technique, but triangulated surface is nor ideal and needs time for correction.
Can you share the file? I have some ideas that I want to try on it.
The thing is that offset to within doesn't work. Maybe because AutoCAD can't find its center?
Here's the problem, you have 15 gazillion verticies (yes, I counted) on that buffer because of the way it was created (i.e. no curves). When doing anything with that, it's going to bomb out on you so get rid of all the little segments.
HERE is my solution.
Hello Brian,
You solution works for parallel offsets, but what happens when the two sides of your figure are not parallel? How do you ensure your new polyline is centered between points at a particular station?
Tim