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Dear dev team, <br>
<br>
I would like to propose an idea for the 2017 GSoC (it is already on
the GSoC 2017 GRASS wiki page). <br>
<br>
It will be focused on 'meaningful' cutline generation. I recently
read a paper describing a method for cutline generation (see below
[1] for the article, [2] for more references). <br>
<br>
The procedure is composed of the following main steps: <br>
1) Apply a High-pass filter - the "Prewitt South" filter (<a
href="https://en.wikipedia.org/wiki/Prewitt_operator">https://en.wikipedia.org/wiki/Prewitt_operator</a>)
to produce an edge image;<br>
2) Apply a low-pass filter (mean for example) on the previous
result;<br>
3) Find the starting and finishing points (just based on pixel
values in the first/last column/row);<br>
4) Create an adjacency matrix on the result of 2) and use weights to
give higher costs for specific directions (and force the cutline in
to be quite linear between starting and finishing points);<br>
5) Use the Dijkstra's algorithm (<a
href="https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm">https://en.wikipedia.org/wiki/Dijkstra's_algorithm</a>)
to find the optimal cutline with a lowest cost between the starting
and finishing point<br>
<br>
Finding meaningful cutline in the image could be very interesting
for tiling images in order to process segmentation in parallel.
Instead of using arbitrary linear tiling, the segmented tiles could
then be merged without post-processing of segments touching the
tile's border. <br>
<br>
If this algorithm would be implemented during the GSoC, it could be
further adapted for huge enhancement of i.image.mosaic to enable
mosaicking of overlapping scenes using cutline and become a real
alternative to proprietary software (<a
href="http://gis.stackexchange.com/questions/127310/how-to-create-a-mosaic-in-qgis-with-cutline-and-feathering-for-landsat-8-imagery">http://gis.stackexchange.com/questions/127310/how-to-create-a-mosaic-in-qgis-with-cutline-and-feathering-for-landsat-8-imagery</a>).
<br>
<br>
As the proposed solution [1] for cutline is working on a single
image, It should be adapted to take into account pixel values of two
images so.<br>
I can give a support for the content of the project, but I don't
have the necessary programming skills for supervision of GSoC
student. So, I would like to know if someone would be interested by
being the mentor for this project ! <br>
Concerning the language requirements for this project I guess it
will be C ?<br>
<br>
[1] Soares, Anderson Reis, Thales Sehn Körting, et Leila Maria
Garcia Fonseca. 2016. « Improvements of the divide and segment
method for parallel image segmentation ». Brazilian Journal of
Cartography 68 (6). <a
href="https://www.researchgate.net/publication/286929006_Improvements_of_the_divide_and_segment_method_for_parallel_image_segmentation">https://www.researchgate.net/publication/286929006_Improvements_of_the_divide_and_segment_method_for_parallel_image_segmentation</a><br>
<br>
[2] Körting, Thales Sehn, Emiliano Ferreira Castejon, et Leila Maria
Garcia Fonseca. 2013. « The Divide and Segment Method for Parallel
Image Segmentation ». In Advanced Concepts for Intelligent Vision
Systems, 504 15. Springer, Cham. doi:10.1007/978-3-319-02895-8_45. <a
href="https://www.researchgate.net/publication/265794792_The_Divide_and_Segment_Method_for_Parallel_Image_Segmentation">https://www.researchgate.net/publication/265794792_The_Divide_and_Segment_Method_for_Parallel_Image_Segmentation</a><br>
<br>
Best, <br>
<div class="moz-signature">-- <br>
<p><strong><span style="font-size: small;">M. GRIPPA Taïs</span></strong><br>
Geographer - Phd student IGEAT - ANAGEO<br>
ULB CP 130/03 Av. F.D. Roose<span style="white-space: pre-wrap;">velt, 50 - 1050 Bruxelles</span><br>
Tél: 02/650.68.06<br>
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