[GRASS-user] Create a point along a line in a specified distance from another point

Hi,

is there an easy straight forward command to create a new point on a line that is in a specified distance (e.g. 1000 m) from another point (on the same line)?

Just an example (of course from river science): I have a sampling site on a river line. I’d like to use these new point(s) to break the original river lines in order to extract a line segment that is exactly e.g. 2000 m long (1000 up- and downstream the sampling site).

I had a look in v.to.points but this tool only creates points in equidistant steps irrespective of any other points (e.g. sampling points). Another option would be using v.buffer around the sampling points and then v.overlay. However, this approach would “cut” the river lines in euclidean distance from the sampling site rather then in line/river distance.

Any suggestions?

/J

On 17/10/17 15:42, Johannes Radinger wrote:

Hi,

is there an easy straight forward command to create a new point on a line that is in a specified distance (e.g. 1000 m) from another point (on the same line)?

Just an example (of course from river science): I have a sampling site on a river line. I'd like to use these new point(s) to break the original river lines in order to extract a line segment that is exactly e.g. 2000 m long (1000 up- and downstream the sampling site).

I had a look in v.to.points but this tool only creates points in equidistant steps irrespective of any other points (e.g. sampling points). Another option would be using v.buffer around the sampling points and then v.overlay. However, this approach would "cut" the river lines in euclidean distance from the sampling site rather then in line/river distance.

Any suggestions?

v.net.iso ?

Moritz

On 17/10/17 16:10, Moritz Lennert wrote:

On 17/10/17 15:42, Johannes Radinger wrote:

Hi,

is there an easy straight forward command to create a new point on a line that is in a specified distance (e.g. 1000 m) from another point (on the same line)?

Just an example (of course from river science): I have a sampling site on a river line. I'd like to use these new point(s) to break the original river lines in order to extract a line segment that is exactly e.g. 2000 m long (1000 up- and downstream the sampling site).

I had a look in v.to.points but this tool only creates points in equidistant steps irrespective of any other points (e.g. sampling points). Another option would be using v.buffer around the sampling points and then v.overlay. However, this approach would "cut" the river lines in euclidean distance from the sampling site rather then in line/river distance.

Any suggestions?

v.net.iso ?

Or perhaps better: v.lrs.segment ?

Moritz

Moritz Lennert wrote

On 17/10/17 16:10, Moritz Lennert wrote:

On 17/10/17 15:42, Johannes Radinger wrote:

Hi,

is there an easy straight forward command to create a new point on a
line that is in a specified distance (e.g. 1000 m) from another point
(on the same line)?

Just an example (of course from river science): I have a sampling site
on a river line. I'd like to use these new point(s) to break the
original river lines in order to extract a line segment that is
exactly e.g. 2000 m long (1000 up- and downstream the sampling site).

I had a look in v.to.points but this tool only creates points in
equidistant steps irrespective of any other points (e.g. sampling
points). Another option would be using v.buffer around the sampling
points and then v.overlay. However, this approach would "cut" the
river lines in euclidean distance from the sampling site rather then
in line/river distance.

Any suggestions?

v.net.iso ?

Or perhaps better: v.lrs.segment ?

Moritz
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See

https://grass.osgeo.org/grass72/manuals/addons/v.fixed.segmentpoints.html

to get equidistant points along a line. It's a wrapper about v.segment.

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best regards
Helmut
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