Extract vertices QGIS 3
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I am using Extract vertices in QGIS 3. The table in result shows angles. What do those angles mean?
qgis vertices extract angles
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
add a comment |
I am using Extract vertices in QGIS 3. The table in result shows angles. What do those angles mean?
qgis vertices extract angles
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
2
How about you post some screenshots, of both the table and the corresponding geometries?
– Erik
May 13 at 12:55
@Erik added. Also I label new generated points
– Stepan Khachatryan
May 13 at 13:10
add a comment |
I am using Extract vertices in QGIS 3. The table in result shows angles. What do those angles mean?
qgis vertices extract angles
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
I am using Extract vertices in QGIS 3. The table in result shows angles. What do those angles mean?
qgis vertices extract angles
qgis vertices extract angles
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
edited May 13 at 13:05
Stepan Khachatryan
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
asked May 13 at 12:54
Stepan KhachatryanStepan Khachatryan
465
465
2
How about you post some screenshots, of both the table and the corresponding geometries?
– Erik
May 13 at 12:55
@Erik added. Also I label new generated points
– Stepan Khachatryan
May 13 at 13:10
add a comment |
2
How about you post some screenshots, of both the table and the corresponding geometries?
– Erik
May 13 at 12:55
@Erik added. Also I label new generated points
– Stepan Khachatryan
May 13 at 13:10
2
2
How about you post some screenshots, of both the table and the corresponding geometries?
– Erik
May 13 at 12:55
How about you post some screenshots, of both the table and the corresponding geometries?
– Erik
May 13 at 12:55
@Erik added. Also I label new generated points
– Stepan Khachatryan
May 13 at 13:10
@Erik added. Also I label new generated points
– Stepan Khachatryan
May 13 at 13:10
add a comment |
2 Answers
2
active
oldest
votes
Most of the tool have a description on the right side of the window (if not visible click on the arrow in the upper right corner)
In your case the description read :
Extract vertices
This algorithm takes a line or polygon layer and generates a point layer with points representing the vertices in the
input lines or polygons. The attributes associated to each point are
the same ones associated to the line or polygon that the point belongs
to.
Additional fields are added to the point indicating the vertex index
(beginning at 0), the vertex’s part and its index within the part (as
well as its ring for polygons), distance along original geometry and
bisector angle of vertex for original geometry.
So it seem that the angle is the
bisector angle of vertex for original geometry
EDIT :
I did compare the result with the "angle_at-vertex" expression and I get the same angle for each vertex than those from the Extract vertices tool.
The ""angle_at-vertex" description read :
Returns the bisector angle (average angle) to the geometry for a
specified vertex on a linestring geometry. Angles are in degrees
clockwise from north.
My understanding is that the angle you get at vertex n is the angle between North and the line geometry between vertex n and n+1 in degrees clockwise from north.
Your data doesn't seem to really follow that, could it be related to projection ?
answered May 13 at 13:06
J.RJ.R
3,991222
1
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
add a comment |
Angle value on point is average angle of lines before and after vertex.
First point has no "before line" so its actual angle of line after vertex.
Last point has no "after line" so its actual angle of line before vertex.
Angle is in degrees clockwise from north to line geometry.
answered May 13 at 16:17
MatMat
1,111617
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Most of the tool have a description on the right side of the window (if not visible click on the arrow in the upper right corner)
In your case the description read :
Extract vertices
This algorithm takes a line or polygon layer and generates a point layer with points representing the vertices in the
input lines or polygons. The attributes associated to each point are
the same ones associated to the line or polygon that the point belongs
to.
Additional fields are added to the point indicating the vertex index
(beginning at 0), the vertex’s part and its index within the part (as
well as its ring for polygons), distance along original geometry and
bisector angle of vertex for original geometry.
So it seem that the angle is the
bisector angle of vertex for original geometry
EDIT :
I did compare the result with the "angle_at-vertex" expression and I get the same angle for each vertex than those from the Extract vertices tool.
The ""angle_at-vertex" description read :
Returns the bisector angle (average angle) to the geometry for a
specified vertex on a linestring geometry. Angles are in degrees
clockwise from north.
My understanding is that the angle you get at vertex n is the angle between North and the line geometry between vertex n and n+1 in degrees clockwise from north.
Your data doesn't seem to really follow that, could it be related to projection ?
answered May 13 at 13:06
J.RJ.R
3,991222
1
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
add a comment |
Most of the tool have a description on the right side of the window (if not visible click on the arrow in the upper right corner)
In your case the description read :
Extract vertices
This algorithm takes a line or polygon layer and generates a point layer with points representing the vertices in the
input lines or polygons. The attributes associated to each point are
the same ones associated to the line or polygon that the point belongs
to.
Additional fields are added to the point indicating the vertex index
(beginning at 0), the vertex’s part and its index within the part (as
well as its ring for polygons), distance along original geometry and
bisector angle of vertex for original geometry.
So it seem that the angle is the
bisector angle of vertex for original geometry
EDIT :
I did compare the result with the "angle_at-vertex" expression and I get the same angle for each vertex than those from the Extract vertices tool.
The ""angle_at-vertex" description read :
Returns the bisector angle (average angle) to the geometry for a
specified vertex on a linestring geometry. Angles are in degrees
clockwise from north.
My understanding is that the angle you get at vertex n is the angle between North and the line geometry between vertex n and n+1 in degrees clockwise from north.
Your data doesn't seem to really follow that, could it be related to projection ?
answered May 13 at 13:06
J.RJ.R
3,991222
1
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
add a comment |
Most of the tool have a description on the right side of the window (if not visible click on the arrow in the upper right corner)
In your case the description read :
Extract vertices
This algorithm takes a line or polygon layer and generates a point layer with points representing the vertices in the
input lines or polygons. The attributes associated to each point are
the same ones associated to the line or polygon that the point belongs
to.
Additional fields are added to the point indicating the vertex index
(beginning at 0), the vertex’s part and its index within the part (as
well as its ring for polygons), distance along original geometry and
bisector angle of vertex for original geometry.
So it seem that the angle is the
bisector angle of vertex for original geometry
EDIT :
I did compare the result with the "angle_at-vertex" expression and I get the same angle for each vertex than those from the Extract vertices tool.
The ""angle_at-vertex" description read :
Returns the bisector angle (average angle) to the geometry for a
specified vertex on a linestring geometry. Angles are in degrees
clockwise from north.
My understanding is that the angle you get at vertex n is the angle between North and the line geometry between vertex n and n+1 in degrees clockwise from north.
Your data doesn't seem to really follow that, could it be related to projection ?
answered May 13 at 13:06
J.RJ.R
3,991222
Most of the tool have a description on the right side of the window (if not visible click on the arrow in the upper right corner)
In your case the description read :
Extract vertices
This algorithm takes a line or polygon layer and generates a point layer with points representing the vertices in the
input lines or polygons. The attributes associated to each point are
the same ones associated to the line or polygon that the point belongs
to.
Additional fields are added to the point indicating the vertex index
(beginning at 0), the vertex’s part and its index within the part (as
well as its ring for polygons), distance along original geometry and
bisector angle of vertex for original geometry.
So it seem that the angle is the
bisector angle of vertex for original geometry
EDIT :
I did compare the result with the "angle_at-vertex" expression and I get the same angle for each vertex than those from the Extract vertices tool.
The ""angle_at-vertex" description read :
Returns the bisector angle (average angle) to the geometry for a
specified vertex on a linestring geometry. Angles are in degrees
clockwise from north.
My understanding is that the angle you get at vertex n is the angle between North and the line geometry between vertex n and n+1 in degrees clockwise from north.
Your data doesn't seem to really follow that, could it be related to projection ?
answered May 13 at 13:06
J.RJ.R
3,991222
edited May 13 at 14:19
answered May 13 at 13:06
J.RJ.R
3,991222
answered May 13 at 13:06
J.RJ.R
3,991222
answered May 13 at 13:06
J.RJ.R
3,991222
3,991222
1
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
add a comment |
1
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
1
1
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
Dear @J.R I read it. It seems the first point (79.675) is the angle between the north arrow and first line. But the second point (93.566) is not the angle between the first and second lines.
– Stepan Khachatryan
May 13 at 13:17
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
That's true, and vertex 2 and 6 have similar value (around 115 and 111) but the angle are definitely not similar..., so no idea of what's going on here
– J.R
May 13 at 13:52
add a comment |
Angle value on point is average angle of lines before and after vertex.
First point has no "before line" so its actual angle of line after vertex.
Last point has no "after line" so its actual angle of line before vertex.
Angle is in degrees clockwise from north to line geometry.
answered May 13 at 16:17
MatMat
1,111617
add a comment |
Angle value on point is average angle of lines before and after vertex.
First point has no "before line" so its actual angle of line after vertex.
Last point has no "after line" so its actual angle of line before vertex.
Angle is in degrees clockwise from north to line geometry.
answered May 13 at 16:17
MatMat
1,111617
add a comment |
Angle value on point is average angle of lines before and after vertex.
First point has no "before line" so its actual angle of line after vertex.
Last point has no "after line" so its actual angle of line before vertex.
Angle is in degrees clockwise from north to line geometry.
answered May 13 at 16:17
MatMat
1,111617
Angle value on point is average angle of lines before and after vertex.
First point has no "before line" so its actual angle of line after vertex.
Last point has no "after line" so its actual angle of line before vertex.
Angle is in degrees clockwise from north to line geometry.
answered May 13 at 16:17
MatMat
1,111617
answered May 13 at 16:17
MatMat
1,111617
answered May 13 at 16:17
MatMat
1,111617
answered May 13 at 16:17
MatMat
1,111617
1,111617
add a comment |
add a comment |
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2
How about you post some screenshots, of both the table and the corresponding geometries?
– Erik
May 13 at 12:55
@Erik added. Also I label new generated points
– Stepan Khachatryan
May 13 at 13:10