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thin out nodes of a polyline

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#1
Rob

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Does anyone know the name of the tool that decreases the number of nodes in a shapefile polyline?

Would be like the AI simplify path command for Arc.

Thought it was in there, now can't find it.

tia.

rob

#2
Eric Wolf

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Do you want to remove nodes or just vertices?

If it's vertices, then you want to use a generalization algorithm. Look in the toolbox under Generalize.

Nodes differ from vertices in that they create topology. They are a bit harder to clean up.

I did just happen to write a Python script yesterday that converts "extraneous" nodes to vertices. But you don't want to do that unless you understand why those nodes were there in the first place. Frequently, they mark topology with another feature class. Like a stream may have a node that doesn't denote a change in stream order, but rather, marks the point the stream is crossed by a road.

-Eric

Does anyone know the name of the tool that decreases the number of nodes in a shapefile polyline?

Would be like the AI simplify path command for Arc.

Thought it was in there, now can't find it.

tia.

rob



#3
pfyfield

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Generalize is under Data Management Tools in the toolbox.

There's Simplify Line and Smooth Line, each with a choice of a couple algorithms. Simplify Line is what you want.
Paul Fyfield
Cartographer, Bureau of Land Management
Oregon State Office
Portland, Oregon
pfyfield@blm.gov

#4
Rob

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that's what i had thought. must be that this is just an arc view license.

thanks eric for you explanation.

#5
Unit Seven

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Or try mapshaper.org. Will take up to a 16mb shp file from memory and is a real-time interactive generalization for those who prefer to see results rather than thinking in numbers.
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#6
Rob

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great idea sam. I've used that tool plenty in the past. can't believe how completely that tool skipped my mind...




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