[GRASS-user] Cut a floodplain polygon with 1meter wide polygons perpendicular to its river channel

[Shane Carey]

Hi All,

I am getting closer to what I want. Is there a way to cut the floodplain
polygon where it "narrows" in, i.e. at the green lines on slide 6.
I need some way of automating this.
https://docs.google.com/presentation/d/1x7IQ3BJlLLSb6R2atxIIiaeWzyCqCZQ3uWaGPZyo6ds/edit#slide=id.g45038c0552_0_0
Thanks
Le gach dea ghui,
*Shane Carey*
*GIS and Data Solutions Consultant*


On Tue, Oct 16, 2018 at 10:45 AM Shane Carey <careyshan at gmail.com> wrote:

> What about obtaining the main direction of the river (North - South/ East-
> West) and creating the rows/columns based on that? Any advice/ help would
> be appreciated!
> Thanks all
> Le gach dea ghui,
> *Shane Carey*
> *GIS and Data Solutions Consultant*
>
>
> On Tue, Oct 16, 2018 at 7:49 AM Shane Carey <careyshan at gmail.com> wrote:
>
>> Ok, I seem to be getting closer to what I need. It works well where the
>> river is perpendicular to the column (see slide 3) but where it is
>> parrallel (see slide 4), I would need to obtain a rows map. Is there any
>> way of being able to tell it to create rows or columns based on the river
>> direction?
>>
>> <http://goog_326768947>
>>
>> https://docs.google.com/presentation/d/1x7IQ3BJlLLSb6R2atxIIiaeWzyCqCZQ3uWaGPZyo6ds/edit?usp=sharing
>>
>> Or if you think there is a better way of reaching my end goal (slide 2),
>> I would be interested in hearing your thoughts.
>> Thanks
>>
>> Thanks
>>
>> Le gach dea ghui,
>> *Shane Carey*
>> *GIS and Data Solutions Consultant*
>>
>>
>> On Tue, Oct 16, 2018 at 6:38 AM Johannes Radinger <
>> johannesradinger at gmail.com> wrote:
>>
>>> It seems that would would like to have your floodplain cut based on the
>>> columns of the underlying raster-resolution (and not perpendicular to the
>>> river line as initially stated). You could use mapcalc to generate a column
>>> raster map (r.mapcalc expression="colmap = col()") which you could then
>>> transform to a vector map and use to intersect with your floodplain vector.
>>>
>>> best
>>> Johannes
>>>
>>> On Tue, Oct 16, 2018 at 1:24 AM Shane Carey <careyshan at gmail.com> wrote:
>>>
>>>> Hi All,
>>>>
>>>> I don't think v.transects is going to work for me as lines appear to be
>>>> cutting across each other. Is there another tool in Grass that can cut the
>>>> floodplain polygon into 5m lengths (as green lines in image attached)
>>>>
>>>> Thanks
>>>>
>>>>
>>>>
>>>> On Luan 15 DFómh 2018 at 15:38, Shane Carey <careyshan at gmail.com>
>>>> wrote:
>>>>
>>>>> Great thanks, is there anything available that will snap these lines
>>>>> to the polygon edges?
>>>>>
>>>>> Thanks
>>>>> Le gach dea ghui,
>>>>> *Shane Carey*
>>>>> *GIS and Data Solutions Consultant*
>>>>>
>>>>>
>>>>> On Mon, Oct 15, 2018 at 3:30 PM Markus Neteler <neteler at osgeo.org>
>>>>> wrote:
>>>>>
>>>>>> On Sun, Oct 14, 2018 at 11:28 PM Shane Carey <careyshan at gmail.com>
>>>>>> wrote:
>>>>>> >
>>>>>> > Hi,
>>>>>> >
>>>>>> > I need to cut a floodplain polygon into one meter strips which are
>>>>>> perpendicular to the river. This needs to be an automated process. Just
>>>>>> wondering has anyone ever done this or similar in Grass GIS through python
>>>>>> or a bash script?
>>>>>> >
>>>>>> > The link attached shows two slides. Stage one is the first slide
>>>>>> and slide two is what I hope to end up with.
>>>>>> >
>>>>>> >
>>>>>> https://docs.google.com/presentation/d/1x7IQ3BJlLLSb6R2atxIIiaeWzyCqCZQ3uWaGPZyo6ds/edit?usp=sharing
>>>>>>
>>>>>> This addon seems to do (similar) perpendicular line creation:
>>>>>>   v.civil - Generates a alignment for designing roads, channels, and
>>>>>> ports in civil engineering
>>>>>>   https://grass.osgeo.org/grass7/manuals/addons/v.civil.html
>>>>>>
>>>>>> Best
>>>>>> Markus
>>>>>>
>>>>>> --
>>>>>> Markus Neteler, PhD
>>>>>> http://www.mundialis.de - free data with free software
>>>>>> http://grass.osgeo.org
>>>>>> http://courses.neteler.org/blog
>>>>>>
>>>>> --
>>>> Le gach dea ghui,
>>>> *Shane Carey*
>>>> *GIS and Data Solutions Consultant*
>>>> _______________________________________________
>>>> grass-user mailing list
>>>> grass-user at lists.osgeo.org
>>>> https://lists.osgeo.org/mailman/listinfo/grass-user
>>>
>>>
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