[gdal-dev] Countour polygons instead of lines

[Roberto Ribeiro]

In cases of cliffs and such (i.e. sudden drops in altitude), traditional
photogrammetric softwares like PCI and Erdas work with break lines, as in,
you literally draw a line along edges you want computed discontinuously.
That is not really practical to do in command-line GDAL, though you could
import a previously created line vector and tell the algorithm to process
with those in mind.

2017-10-20 16:18 GMT-02:00 Andrew C Aitchison <andrew at aitchison.me.uk>:

> On Fri, 20 Oct 2017, Vincent Mora wrote:
>
> I'll also try the gdal_polygonize approach, but I don't think it's the
>> same thingl: with raster-classif + gdal_polygonize, if you have 3
>> classes 1,2,3 polygons from 1 can touch a polygon from 3, with contour
>> lines there will always be a polygon of class 2 in between.
>>
>> Or am I missing something.
>>
>> If someone believes I'm doing something useless and/or stupid (that also
>> happens), please do tell.
>>
>
> Can you polygonize contours across a vertical cliff ?
> If so, 2 may be "between" 1 and 3, but at some points they may all touch.
>
> On some maps, contours become discontinuous around cliffs and quarries.
>
> --
> Andrew C Aitchison
>
>
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