Curve reconstruction

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ven
Posts: 4
Joined: Thu Jun 07, 2012 5:45 pm

Curve reconstruction

Postby ven » Wed Feb 27, 2013 4:10 pm

Hi,

I have a vector generated from bitmap map trace where I segmented topological contours. These contours have gaps that were caused by various labellings, graticules and other line objects overlaid on top of contours in source bitmap.

I've read couple of papers about this problem, and am aware of some curve reconstruction algorithms that authors reported to be successful in automating this process. Thinking about it, as a challenge that it represents to me as I'd have to do this through programming, while I'm not confident that I'll be able to see the final result, I thought that maybe Inkscape as a vector application has some instrument that can be used for this task.

To explain through pictures... I have this kind of bitmap:

Image

which I trace to this vector:

Image

and I aim toward vector with reconstructed contours, where gaps should be corrected automatically:

Image

and by automatically I mean on all selected lines, so that I won't have to select each group of contour line separately and do join lines, as that is too much time consuming process.

Thanks


ven
Posts: 4
Joined: Thu Jun 07, 2012 5:45 pm

Re: Curve reconstruction

Postby ven » Thu Feb 28, 2013 9:05 pm

Ragnar, thanks for your reply

1. Papers - I know majority of those paper (recognized just by the URLs). Closing with Delaunay triangulation seemed like the way I should go, but programming it is far from trivial, although procedure is plastically explained.

2. GIS tools - There is no GIS tool to my knowledge, that will close the gaps if contours aren't labeled. And if I need to label the contours, then I might as well close the gaps as it will require same amount of time.

3. Public DEMs - I have ASTER data, which is most accurate publicly available set, but I'm not after DEMs. I want to convert older map that was used for some modeling years ago and extract certain values.

I hoped that having the lines defined as vectors, I might find some helpers in popular vector application.

User avatar
ragstian
Posts: 1181
Joined: Thu Oct 11, 2012 2:44 am
Location: Stavanger-Norway

Re: Curve reconstruction

Postby ragstian » Fri Mar 01, 2013 3:58 am

Hi.

Sorry for stating the obvious! ;)

matplotlib (for python) can do "Delaunay" right out of the "box".
http://matplotlib.org/index.html
http://matplotlib.org/examples/pylab_ex ... t=delaunay
http://matplotlib.org/examples/pylab_ex ... t=delaunay
http://matplotlib.org/examples/pylab_ex ... t=delaunay

How you can use "Delaunay" to "splice" gaps in the map contours is way over my head! :D

RGDS
Ragnar
Good Luck!
( ͡° ͜ʖ ͡°)
RGDS
Ragnar


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