[GRASS-dev] new addon: i.cutlines - Creates semantically meaningful tile borders

[Moritz Lennert]

Hi Markus,

On 13/08/18 13:41, Markus Neteler wrote:
> Hi Moritz, all,
> 
> On Tue, Mar 13, 2018 at 4:06 PM, Moritz Lennert
> <mlennert at club.worldonline.be> wrote:
>> Hi to all,
>>
>> A new addon is available [1]: i.cutlines tiles the images into tiles with
>> irregular borders that avoid cutting through meaningful objects. This allows
>> tiling an image for parallel processing while avoiding border effects.
> ...
>> [1] https://grass.osgeo.org/grass74/manuals/addons/i.cutlines.html
> 
> we are currently trying to use this approach on a huge (?) area of 50
> gigapixels of aerial images (i.e., the free openNRW 10cm orthophotos)
> which we have to classify.
> 
> In future the areas we'll have to process may be even bigger. Right
> now, as far as I understand, i.cutlines is reading the entire images.
> This becomes increasingly difficult with bigger areas due to hardware
> limitations.
> 
> Do you have a suggestion how to deal with that? Kind of chicken and
> egg problem? :)

AFAIK, the only moment where i.cutlines potentially reads the whole 
image would be in the edge detection part. That's why there is the 
tiling option to avoid just that. So, unless I'm forgetting something, 
you should be able to work on large images. If you have seen this crash 
the module, please file a bug report.

Note that for versions < 7.5 (I'll have to check whether Pietro's fix 
was backported to 7.4) there is a parameter name conflict between i.zc 
and the GridModule class used for the tiling, so you'd have to use i.edge.

Moritz