Re: [GRASS-dev] GSoC ideas - vector legend, medial axis

[Markus Metz]

On Thu, Feb 20, 2014 at 10:47 PM, Anna Petrášová  wrote:
>
>
>
> On Thu, Feb 20, 2014 at 4:06 PM, Markus Metz 
> wrote:
>>
>> On Thu, Feb 20, 2014 at 9:08 AM, Tereza Fiedlerová
>>  wrote:
>> > Hello,
>> >
>> > I'm thinking about participating in GSoC this year, if I find some
>> > interesting topic. I went through GRASS GSoC ideas. The two most
>> > interesting
>> > for me are Vector legend and Extracting the medial axis of polygon. I
>> > would
>> > appreciate if anyone can give me more information to these topics.
>> >
>> > The first one is maybe described enough and I just need to study that
>> > more
>> > to understand it better, but still anything more regarding that would be
>> > appreciated.
>> >
>> > The medial axis is not really clear to me. I know what is medial axis,
>> > but I
>> > would like to know more about desired results. How it should be
>> > integrated
>> > to GRASS (some new module?). Is it necessary to write it in C (why not
>> > python)? Should the result algorithm extract the exact medial axis or
>> > the
>> > approximation? ...
>>
>> A good approximation would be fine. It would be necessary to write in
>> C for efficiency reasons and because C library functions need to be
>> heavily used. Additionally, search structures like balanced binary
>> search trees and min heaps are needed which are already implemented in
>> GRASS as C code. I have already written 2 different C modules trying
>> to extract the medial axis, both are incredibly complex and none of
>> them works properly. I am familiar with GRASS, C, and Python and like
>> to use the easiest approach. In this case I am pretty sure that the
>> easiest and most appropriate approach is using C, not Python.
>>
>> Therefore I would recommend a good knowledge of C and some knowledge
>> of the GRASS C API for this project.
>>
>> Markus M
>
>
>
> Just in case it would be useful (at least for Tereza, it's mostly in Czech):
>
> http://web.natur.cuni.cz/~bayertom/Adk/adk7.pdf
>
> this is a presentation on straight skeleton algorithm (if medial axis is the
> same or at least related?).

A straight skeleton is not the same like a medial axis: only the
medial axis is equidistant to the polygon boundaries.

Markus M

>
> Anna
>
>>
>> >
>> > And one more question. Is any of these topics suitable for me if I am
>> > not
>> > experienced in GRASS at all?
>> >
>> > Thank you
>> >
>> > Tereza Fiedlerová
>> >
>> > ___
>> > grass-dev mailing list
>> > grass-dev@lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/grass-dev
>> ___
>> grass-dev mailing list
>> grass-dev@lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-dev
>
>
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Re: [GRASS-dev] [GRASS GIS] #1775: v.surf.rst does not respect mask

[GRASS GIS]

#1775: v.surf.rst does not respect mask
-+--
 Reporter:  cmbarton |   Owner:  grass-dev@…  
 Type:  defect   |  Status:  new  
 Priority:  major|   Milestone:  7.0.0
Component:  Vector   | Version:  svn-trunk
 Keywords:  v.surf.rst   |Platform:  Unspecified  
  Cpu:  Unspecified  |  
-+--
Changes (by bhlevca):

  * priority:  normal => major


Comment:

 I am curios what is the status of this.
 Basically the current code does not allow to interpolate with a mask
 because of the ERROR: Input window changed while maps are open for read.

 I don't understand Glynn's explanation about multiple resolutions. I have
 one mask and a vector layer and I want to generate a raster based on the
 values of the vector layer and to be limited by the boundaries provided by
 the mask, which in my opinion could be a vector Polygon as well.

 I would say this is a pretty major feature.

-- 
Ticket URL: 
GRASS GIS 

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Re: [GRASS-dev] GSoC ideas - vector legend, medial axis

[Anna Petrášová]

On Thu, Feb 20, 2014 at 4:06 PM, Markus Metz
wrote:

> On Thu, Feb 20, 2014 at 9:08 AM, Tereza Fiedlerová
>  wrote:
> > Hello,
> >
> > I'm thinking about participating in GSoC this year, if I find some
> > interesting topic. I went through GRASS GSoC ideas. The two most
> interesting
> > for me are Vector legend and Extracting the medial axis of polygon. I
> would
> > appreciate if anyone can give me more information to these topics.
> >
> > The first one is maybe described enough and I just need to study that
> more
> > to understand it better, but still anything more regarding that would be
> > appreciated.
> >
> > The medial axis is not really clear to me. I know what is medial axis,
> but I
> > would like to know more about desired results. How it should be
> integrated
> > to GRASS (some new module?). Is it necessary to write it in C (why not
> > python)? Should the result algorithm extract the exact medial axis or the
> > approximation? ...
>
> A good approximation would be fine. It would be necessary to write in
> C for efficiency reasons and because C library functions need to be
> heavily used. Additionally, search structures like balanced binary
> search trees and min heaps are needed which are already implemented in
> GRASS as C code. I have already written 2 different C modules trying
> to extract the medial axis, both are incredibly complex and none of
> them works properly. I am familiar with GRASS, C, and Python and like
> to use the easiest approach. In this case I am pretty sure that the
> easiest and most appropriate approach is using C, not Python.
>
> Therefore I would recommend a good knowledge of C and some knowledge
> of the GRASS C API for this project.
>
> Markus M
>


Just in case it would be useful (at least for Tereza, it's mostly in Czech):

http://web.natur.cuni.cz/~bayertom/Adk/adk7.pdf

this is a presentation on straight skeleton algorithm (if medial axis is
the same or at least related?).

Anna


> >
> > And one more question. Is any of these topics suitable for me if I am not
> > experienced in GRASS at all?
> >
> > Thank you
> >
> > Tereza Fiedlerová
> >
> > ___
> > grass-dev mailing list
> > grass-dev@lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-dev
> ___
> grass-dev mailing list
> grass-dev@lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-dev
>
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Re: [GRASS-dev] GSoC ideas - vector legend, medial axis

[Markus Metz]

On Thu, Feb 20, 2014 at 9:08 AM, Tereza Fiedlerová
 wrote:
> Hello,
>
> I'm thinking about participating in GSoC this year, if I find some
> interesting topic. I went through GRASS GSoC ideas. The two most interesting
> for me are Vector legend and Extracting the medial axis of polygon. I would
> appreciate if anyone can give me more information to these topics.
>
> The first one is maybe described enough and I just need to study that more
> to understand it better, but still anything more regarding that would be
> appreciated.
>
> The medial axis is not really clear to me. I know what is medial axis, but I
> would like to know more about desired results. How it should be integrated
> to GRASS (some new module?). Is it necessary to write it in C (why not
> python)? Should the result algorithm extract the exact medial axis or the
> approximation? ...

A good approximation would be fine. It would be necessary to write in
C for efficiency reasons and because C library functions need to be
heavily used. Additionally, search structures like balanced binary
search trees and min heaps are needed which are already implemented in
GRASS as C code. I have already written 2 different C modules trying
to extract the medial axis, both are incredibly complex and none of
them works properly. I am familiar with GRASS, C, and Python and like
to use the easiest approach. In this case I am pretty sure that the
easiest and most appropriate approach is using C, not Python.

Therefore I would recommend a good knowledge of C and some knowledge
of the GRASS C API for this project.

Markus M

>
> And one more question. Is any of these topics suitable for me if I am not
> experienced in GRASS at all?
>
> Thank you
>
> Tereza Fiedlerová
>
> ___
> grass-dev mailing list
> grass-dev@lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-dev
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Re: [GRASS-dev] [GRASS GIS] #2176: create .grass7 directory at startup

[GRASS GIS]

#2176: create .grass7 directory at startup
--+-
  Reporter:  lucadelu |   Owner:  grass-dev@…  
  Type:  defect   |  Status:  closed   
  Priority:  normal   |   Milestone:  7.0.0
 Component:  Default  | Version:  svn-trunk
Resolution:  fixed|Keywords:   
  Platform:  Unspecified  | Cpu:  Unspecified  
--+-
Changes (by lucadelu):

  * status:  new => closed
  * resolution:  => fixed


Comment:

 Replying to [comment:1 martinl]:

 > Your patch seems to be reasonable. wxGUI behaves similarly
 source:grass/trunk/gui/wxpython/core/settings.py#L989

 Ok, fixed in r59106

-- 
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Re: [GRASS-dev] GSoC ideas - vector legend, medial axis

[Margherita Di Leo]

Hi Tereza!


On Thu, Feb 20, 2014 at 9:08 AM, Tereza Fiedlerová wrote:
>
>
> And one more question. Is any of these topics suitable for me if I am not
> experienced in GRASS at all?
>
> Please consider the idea on metadata, that requires a limited knowledge of
GRASS I would say



-- 
Best regards,

Dr. Margherita DI LEO
Scientific / technical project officer

European Commission - DG JRC
Institute for Environment and Sustainability (IES)
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-...@jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not
in any circumstance be regarded as stating an official position of the
European Commission.
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[GRASS-dev] GSoC ideas - vector legend, medial axis

[Tereza Fiedlerová]

Hello,

I'm thinking about participating in GSoC this year, if I find some
interesting topic. I went through GRASS GSoC ideas. The two most
interesting for me are Vector legend and Extracting the medial axis of
polygon. I would appreciate if anyone can give me more information to these
topics.

The first one is maybe described enough and I just need to study that more
to understand it better, but still anything more regarding that would be
appreciated.

The medial axis is not really clear to me. I know what is medial axis, but
I would like to know more about desired results. How it should be
integrated to GRASS (some new module?). Is it necessary to write it in C
(why not python)? Should the result algorithm extract the exact medial axis
or the approximation? ...

And one more question. Is any of these topics suitable for me if I am not
experienced in GRASS at all?

Thank you

Tereza Fiedlerová
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