[GRASS-user] serious problem with "ROUND-OFF"

[achim]

update for 1)

due to my raster-resolution of 30 seconds, I could get these points by
end-/startpoints-coordinates for each line:

When this coord is very close to 30.00 sec, the geometry of this vert
should be moved...

2) ...could this be done with vertexmove in v.edit, having the
coordinates? ...how can I find out the direction of the line?

A



achim schrieb:
> Dear grass users,
> 
> 
> I think I know what is needed...
> 
> to solve the problem (see below, mainly coming from splitting lines on
> edges between raster-cells), I will have to:
> 1) identify the verts
> 2) move these verts on the line (direction of the line) at certain
> distance (about half grid-size)
> 
> That would solve the problem mainly, but I have no idea how to deal with it.
> Any help, suggestions or opinions are very welcome!
> 
> Thanks in advance,
> Achim
> 
> achim schrieb:
>> Hi all,
>>
>> I have a problem, I really would like to solve, because many problems
>> occur in my theses in further steps.
>>
>> What I do is:
>>
>> 1. I break lines at some lengths.
>> 2. I use both vector- and raster-data for analysis, which is eg.
>> updating points with raster-values or converting lines and points to raster.
>>
>> The Problems are (due to rounding or "non-snapping"?):
>> !Points from lines on the edge between two diagonal cells (see pictures)!
>> These points do:
>> 1. not belong precisely to one cell (compared with the line they come
>> from (see picture v.to.rast.png)
>> 2. These points sometimes don't lie on on the cells, the line is
>> referred to (see picture break.png)
>>
>> Any hints are very welcomed!
>>
>> Thanks in advance,
>> Achim
>>
>>
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