---
name: v.net.visibility
description: Performs visibility graph construction.
keywords: [ vector, network, shortest path, visibility ]
---

# v.net.visibility

Performs visibility graph construction.

=== "Command line"

    **v.net.visibility**
    **input**=*name*
    **output**=*name*
    [**coordinates**=*east,north*]
    [**visibility**=*name*]
    [**--overwrite**]
    [**--verbose**]
    [**--quiet**]
    [**--qq**]
    [**--ui**]

    Example:

    ```sh
    v.net.visibility input=name output=name
    ```

=== "Python (grass.tools)"

    *grass.tools.Tools.v_net_visibility*(**input**,
        **output**,
        **coordinates**=*None*,
        **visibility**=*None*,
        **overwrite**=*None*,
        **verbose**=*None*,
        **quiet**=*None*,
        **superquiet**=*None*)

    Example:

    ```python
    tools = Tools()
    tools.v_net_visibility(input="name", output="name")
    ```

    This grass.tools API is experimental in version 8.5 and expected to be stable in version 8.6.

=== "Python (grass.script)"

    *grass.script.run_command*("***v.net.visibility***",
        **input**,
        **output**,
        **coordinates**=*None*,
        **visibility**=*None*,
        **overwrite**=*None*,
        **verbose**=*None*,
        **quiet**=*None*,
        **superquiet**=*None*)

    Example:

    ```python
    gs.run_command("v.net.visibility", input="name", output="name")
    ```

## Parameters

=== "Command line"

    **input**=*name* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    **output**=*name* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    **coordinates**=*east,north*  
    &nbsp;&nbsp;&nbsp;&nbsp;Coordinates  
    **visibility**=*name*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map containing visible points  
    &nbsp;&nbsp;&nbsp;&nbsp;Add points after computing the visibility graph  
    **--overwrite**  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    **--help**  
    &nbsp;&nbsp;&nbsp;&nbsp;Print usage summary  
    **--verbose**  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    **--quiet**  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    **--qq**  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    **--ui**  
    &nbsp;&nbsp;&nbsp;&nbsp;Force launching GUI dialog

=== "Python (grass.tools)"

    **input** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **output** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: output, vector, *name*  
    **coordinates** : tuple[float, float] | list[float] | str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Coordinates  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, coords, *east,north*  
    **visibility** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map containing visible points  
    &nbsp;&nbsp;&nbsp;&nbsp;Add points after computing the visibility graph  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **overwrite** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **verbose** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **quiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **superquiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  

    Returns:

    **result** : grass.tools.support.ToolResult | None  
    If the tool produces text as standard output, a *ToolResult* object will be returned. Otherwise, `None` will be returned.

    Raises:

    *grass.tools.ToolError*: When the tool ended with an error.

=== "Python (grass.script)"

    **input** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **output** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: output, vector, *name*  
    **coordinates** : tuple[float, float] | list[float] | str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Coordinates  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, coords, *east,north*  
    **visibility** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map containing visible points  
    &nbsp;&nbsp;&nbsp;&nbsp;Add points after computing the visibility graph  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **overwrite** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **verbose** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **quiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **superquiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*

## DESCRIPTION

*v.net.visibility* computes the visibility graph of a vector map
containing lines, areas (boundaries) and points. The visibility graph is
the graph where the nodes are the end point of the lines, boundaries or
simply points. There is an edge between two nodes if they are 'visible'
to each other. Two nodes are visibible if there are no segments in
between of them, i.e. the edge does not intersect any line or boundary
in the vector map. This is useful to compute the shortest path in a
vector map from any two points. To do this, first you need to compute
the visibility graph and from that to compute the shortest path using
*[v.net.path](v.net.path.md)* or *[d.path](d.path.md)*.

**IMPORTANT: the algorithm doesn't work well with intersecting lines
(that includes overlapping)**

## NOTES

If you compute a shortest path after computing the visibility graph you
will notice that this path might go through a vertex of a line. If this
is not what you wanted you might need to process the map in
*[v.buffer](v.buffer.md)*, initially with a small value. Example:

```sh
v.buffer input=map output=bufferedmap buffer=1 type=point,line,area,boundary
```

The first argument is the input map. It supports lines, boundaries (so,
areas) and points. For the algorithm was written to work with lines and
boundaries not intersecting each other (that includes overlapping).  
The resulting map containing the visibility graph is given in the output
map.

If you need to add additional points to compute a shortest path between
them afterwards you can use the **coordinates** parameter, e.g.:

```sh
coordinates=25556200,6686400,25556400,6686600
```

where 25556200,6686400 are the coordinate of the first point and
25556400,6686600 are the coordinates of the second point. Of course you
can give as many points as you need. They will be added to the
visibility graph and edges from them will be computed. You can always
add those points after computing the visibility graph. Simply use the
**visibility** parameter. The input will be the original vector map, the
vis will be the computed visibility graph and the output the new
visibility graph which will be the vis + the new points given with
coordinate (edges will be computed as well).

```sh
v.net.visibility input=map visibility=vis_map output=new_vis_map \
      coordinates=25556200,6686400,25556400,6686600
```

## EXAMPLES

### Example 1

A simple example (North Carolina sample data) showing how to use the
module:

```sh
v.extract input=zipcodes_wake output=areas_7_11_25 cats=7,11,25
g.region vector=zipcodes_wake
d.mon wx0
d.vect areas_7_11_25
v.net.visibility input=areas_7_11_25 output=graph
d.vect graph
d.vect areas_7_11_25 color=red type=boundary
```

### Example 2

An example on how to use *[v.buffer](v.buffer.md)* along with the
module:

```sh
v.buffer input=lines output=buffered_lines buffer=1
v.net.visibility input=buffered_lines output=graph
d.vect graph
d.vect lines col=red
```

### Example 3

An example on how to use the coordinate parameter. This will compute the
visibility graph of the vector map lines with the point 2555678,6686343:

```sh
v.net.visibility input=lines output=graph coordinates=2555678,6686343
d.vect graph
d.vect lines col=red
```

### Example 4

An example (North Carolina sample data) on how to use the coordinate
parameter with the vis parameter. Here the vector map graph is computed
then a new visibility graph is computed from it with the point
669547.97,208348.20 extra:

```sh
v.extract input=zipcodes_wake output=areas_7_11_25 cats=7,11,25
g.region vector=zipcodes_wake
d.mon wx0
d.vect areas_7_11_25
v.net.visibility input=areas_7_11_25 output=graph
v.net.visibility input=areas_7_11_25 visibility=graph output=new_graph \
      coordinates=669547.97,208348.20
d.erase
d.vect areas_7_11_25
echo "symbol basic/star 20 669547.97 208348.20 black red" | d.graph -m
d.vect new_graph
d.vect areas_7_11_25 color=red type=boundary
```

### Example 5

An example for connections of points (Spearfish):

```sh
v.net.visibility input=archsites output=graph
g.region vector=archsites
d.mon wx0
d.vect graph
d.vect archsites col=red
```

### Example 6

Here is an example with artificial data.

![v_net_visibility](v_net_visibility.png)

Load data using here document syntax (Bash and unix-like commands lines
only):

```sh
v.in.ascii input=- output=simple format=standard <<EOF
VERTI:
B  6
 82.19908257  75.21788991
 81.67889908  71.40321101
 83.58623853  71.72522936
 84.3293578   75.21788991
 82.24862385  76.06009174
 82.19908257  75.21788991
C  1 1
 82.88897401  73.66318782
 1     1
C  1 1
 90.72645705  75.61248675
 1     2
C  1 1
 89.37944702  69.51012912
 1     3
C  1 1
 81.60108979  67.78669725
 1     4
B  5
 89.92752294  73.95458716
 92.37981651  75.11880734
 91.56238532  77.29862385
 88.96146789  75.88669725
 89.92752294  73.95458716
B  10
 88.54036697  70.70963303
 87.92192518  70.04087417
 87.89633028  69.00045872
 88.66460807  68.13372867
 90.15108904  68.23290821
 90.9426344   68.97588202
 90.86880734  70.11513761
 90.00144697  70.78336312
 89.06055046  70.95733945
 88.54036697  70.70963303
B  9
 78.73119266  71.35366972
 80.76238532  68.90137615
 84.20550459  66.91972477
 89.87798165  65.35917431
 83.23494031  66.27685175
 80.34278748  68.00837238
 78.38484005  71.40292009
 78.40917431  72.27018349
 78.73119266  71.35366972
EOF
```

Compute the graph:

```sh
v.net.visibility input=simple output=graph
```

## KNOWN ISSUES

In some cases when 3 points or nodes are collinear, some wrong edges are
added. This happens only really rarly and shouldn't be a big problem.
When two points have the exact same x coordinate and are visible, some
wrong edges are added.

## SEE ALSO

*[d.path](d.path.md), [v.net](v.net.md), [v.net.alloc](v.net.alloc.md),
[v.net.iso](v.net.iso.md), [v.net.salesman](v.net.salesman.md),
[v.net.steiner](v.net.steiner.md), [v.to.db](v.to.db.md)*

## AUTHORS

Maximilian Maldacker  
Mentor: Wolf Bergenheim

## SOURCE CODE

Available at: [v.net.visibility source code](https://github.com/OSGeo/grass/tree/main/vector/v.net.visibility)
([history](https://github.com/OSGeo/grass/commits/main/vector/v.net.visibility))  
Latest change: Friday Apr 17 01:04:26 2026 in commit [5a31d54](https://github.com/OSGeo/grass/commit/5a31d549cc0150239894bd2b9e67250af87d38b5)
