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centre line of road polygon

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#1
Gopal

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i am new in GIS, as i have road polygons and i want to make the centre line of each polygons. i dont know what i would do?could you help me

#2
Hans van der Maarel

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i am new in GIS, as i have road polygons and i want to make the centre line of each polygons. i dont know what i would do?could you help me


The CenterLineReplacer in FME does that, though it might get confused at complex intersections.
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#3
Matthew Hampton

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i am new in GIS, as i have road polygons and i want to make the centre line of each polygons. i dont know what i would do?could you help me


If you are using ArcGIS try "Feature to Line" in the Data Management-->Features Toolbox.

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#4
Green Palolo

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As much as I dislike disagreeing with my colleague Mr. Hampton, I don't think the "Feature to Line" will work to create center lines.
I would suggest converting lines to points and then generate Thiessen polygons (ArcInfo license required). The resulting triangle form a line that is the center of the polygons.
Here is an example from a river, but it is the same technique.
Attached File  cl.jpg   209.16KB   66 downloads

#5
Gretchen Peterson

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If you are using ArcGIS you could create an internal buffer, then convert those buffers to lines, then clip the lines using the original road polygons. In theory this sounds like it would work anyway. :)

#6
Green Palolo

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If you are using ArcGIS try "Feature to Line" in the Data Management-->Features Toolbox.


This used to work at version 9.X, but it doesn't with 'improved' functionality at version 10.

#7
Matthew Hampton

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Palolo is correct. I hastily misread the post and my method will just produce a line from a polygon. Finding the centerline is a bit more complicated requiring the creation of thiessen (or voronoi) polygons.

If you are looking for a pushbutton solution I would get Ianko's ET-GeoWizards.

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