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

[Shane Carey]

Had another brainwave. Is it possible to create a perpendicular line at
every vertex that makes up the river line segment?

Thanks
Le gach dea ghui,
*Shane Carey*
*GIS and Data Solutions Consultant*


On Tue, Oct 16, 2018 at 6:15 PM Shane Carey <careyshan at gmail.com> wrote:

> 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
>>>>
>>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20181016/0643791b/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 7472ae91-79b9-4824-b845-fc39b4323df7.jpg
Type: image/jpeg
Size: 45798 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20181016/0643791b/attachment-0001.jpg>