[GRASS-dev] Adding hexagonal rasters to GRASS

Luí­s Moreira de Sousa luis.de.sousa at protonmail.ch
Sun Jul 23 08:50:53 PDT 2017


Dear friends,
I presented hex-utils at the GISTAM conference in April, here is the video:
https://www.youtube.com/watch?v=uLO4HDCVBp0
This was before the QGis plug-in was completed, but for the rest it is pretty much the same story.
Before the FOSS4G-E, in my mind the next phase of the project would be to code the abstraction functionalities in C++ (or C), to make it fully portable and easier to use with other languages, particularly Java. After that would then come a map algebra and spatial analysis.
But as Luca said during the Q/A, it is probably better to start outright within GRASS. This will require the abstraction of the raster concept, together with operations like neighbourhood, number of neighbours, distance to neighbours, etc. With that done most of the raster modules would function the same way for squared and hexagonal rasters. Still, this would require a complete revision of all the raster modules.
For a programmer, the main difference between hexagonal and squared rasters is the cell addressing system: with hexagons the axis are not orthogonal. However, it is possible to store an hexagonal raster in a bi-dimensional array like you would store a squared raster. I wrote an article last year with full details on the HexASCII file format and how to deal with hexagonal cell adressing, but it is still under review. I can not send it to the list, please send me a personal message if you wish to read it.
It would be great if we can take this forward. I imagine it is a load of work, but it will make GRASS an even more awesome system ;)
All the best.

--
Luís Moreira de Sousa
Im Grund 6
CH-8600 Dübendorf
Switzerland
Phone: +41 (0)79 812 62 65
Email: luis.de.sousa at protonmail.ch
URL: https://sites.google.com/site/luismoreiradesousa
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