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How can I prepare data to generate a DTM using points and breaklines, but where every breakline has nodes at different heights. For example, a river valley, which regularly falls, or a dorsal line, where each vertex is a different height.

Thanks for the answer. Tom

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From my point of view, break lines are lines with very different values on each sides (e.g. cliffs), so I would not consider a river as a break line.

I would suggest that you use a TIN interpolation, with your lines used as "structure lines" and checking the "use Z coordinates" (assuming your lines have Z values)

Note : I assume that you use the Interpolation plugin

  • That's what I'm talkimg about! No rivers or clifs has equals altitude along structural lines. I'll be testing that option "use Z coordinates" soon. Thanks. – tomsik Feb 25 '14 at 7:54
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I think that the default behavior for breaklines is that they do follow a valley bottom, or ridgeline. See this for example: http://support.esri.com/en/knowledgebase/GISDictionary/term/breakline

What you're asking is that a line can include specific height values on each vertex along the line, and I don't know of any GIS products that do this. You'd need points at each vertex, and a line as a breakline that follows these vertices, I reckon.

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Consider convert those lines to points, then run the interpolation.

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