[GRASS-dev] i.segment at Community Sprint

[Markus Metz]

On Mon, Feb 11, 2013 at 8:18 PM, Pierre Roudier
<pierre.roudier at gmail.com> wrote:
> Thanks Markus and Eric,
>
> I have similar feedback when testing on various SPOT5 scenes. XL results are
> not entirely identical of course, but reasonably similar, so I support
> Markus' decision.

I can make the results more similar, but one reason why results are
different between i.segment and i.segment.xl is that I had the
impression that i.segment is doing over-segmentation, i.e. merging too
liberally with the effect that some segments (objects), in particular
large segments, were more heterogeneous than justified by the given
merging threshold. With i.segment.xl, I tried to get results that are
very similar to the eCognition results.

Markus M

>
> Cheers,
>
> Pierre
>
> On Feb 11, 2013 10:53 PM, "Markus Metz" <markus.metz.giswork at gmail.com>
> wrote:
>>
>> Hi all,
>>
>> I have tested again i.segment and discovered that for the NC Landsat
>> 2000 imagery the module takes nearly 7 hours for reasonable
>> segmentation. The i.segment.xl module does the same in 10 seconds. The
>> region consists of 250 000 cells, not so much. In the documentation it
>> says that processing the entire ortho image takes about a day. With
>> the xl version it takes about 10 minutes. I am going to move the xl
>> version to trunk and keep the original GSoC version in addons for
>> reference.
>>
>> Markus M
>>
>>
>> On Fri, Feb 8, 2013 at 5:47 AM, Eric Momsen <eric.momsen at gmail.com> wrote:
>> > Sorry for not responding right away, I hadn't realized the code sprint
>> > started (finished?!) already.  There is a paper deadline this month and
>> > a
>> > thesis to write that has consumed my attention...  I don't think I'll
>> > have
>> > time for anything in February.  If noone else wants/needs to do it
>> > sooner, I
>> > hope to have a break between my thesis writing and starting work this
>> > summer.  So in April(???) I will find some time to dedicate to GRASS
>> > code
>> > and/or documents again.
>> >
>> > -Eric
>> >
>> >
>> > On Mon, Feb 4, 2013 at 3:01 AM, Moritz Lennert
>> > <mlennert at club.worldonline.be> wrote:
>> >>
>> >> On 02/02/13 17:37, Markus Metz wrote:
>> >>>
>> >>> On Sat, Feb 2, 2013 at 12:56 PM, Moritz Lennert
>> >>> <mlennert at club.worldonline.be>  wrote:
>> >>>>
>> >>>> Markus and Yann,
>> >>>>
>> >>>> If you have the time it might be a great opportunity to use the
>> >>>> community
>> >>>> sprint to get i.segment from the addons to trunk. What do you think ?
>> >>>
>> >>>
>> >>> I would prefer i.segment.xl for speed reasons and memory control, but
>> >>> the shape functionality in i.segment would need to be ported to
>> >>> i.segment.xl first.
>> >>
>> >>
>> >> I meant i.segment in a global sens, not distinguishing .xl, so that's
>> >> perfectly fine with me.
>> >>
>> >> Eric, any chance for you to look at integrating your work on shapes
>> >> into
>> >> i.segment.xl ?
>> >>
>> >> Moritz
>> >
>> >
>> _______________________________________________
>> grass-dev mailing list
>> grass-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-dev