Visibility Tool in ArcToolbox
ArcMap ArcGIS
Visibility
Tool, Visibility Toolset, 3D Analyst
Toolbox:
Visibility
Determines the raster surface locations visible to a set of observer features, or identifies which observer points are visible from each raster surface location.
1. Input raster
The input surface
raster.
2. Input point or polyline observer features
The feature class that
identifies the observer locations.
The input can be point
or polyline features.
3. Output raster
The output raster.
The output will either
record the number of times that each cell location in the input surface raster
can be seen by the input observation locations (the frequency analysis type),
or record which observer locations are visible from each cell in the raster
surface (the observers type option).
4. Output above ground level raster (optional)
The output
above-ground-level (AGL) raster.
The AGL result is a
raster where each cell value is the minimum height that must be added to an
otherwise nonvisible cell to make it visible by at least one observer.
Cells that were already
visible will have a value of 0 in this output raster.
5. Analysis type (optional)
The visibility analysis
type.
·
FREQUENCY—The output records the number of times that each cell
location in the input surface raster can be seen by the input observation
locations (as points, or as vertices for polyline observer features). This is
the default.
·
OBSERVERS—The output identifies exactly which observer points are
visible from each raster surface location.
6. Use NoData for non-visible cells (optional)
Value assigned to
nonvisible cells.
·
Unchecked—0 is assigned to nonvisible cells. This is the default.
·
Checked—NoData is assigned to nonvisible cells.
7. Z factor (optional)
Number of ground x,y units in one surface z
unit.
The z-factor adjusts the units of measure for
the z units when they are different from the x,y units of the input surface.
The z-values of the input surface are multiplied by the z-factor when
calculating the final output surface.
If the x,y units and z units are in the same
units of measure, the z-factor is 1. This is the default.
If the x,y units and z units are in different units of measure, the z-factor must be set to the appropriate factor, or the results will be incorrect. For example, if your z units are feet and your x,y units are meters, you would use a z-factor of 0.3048 to convert your z units from feet to meters (1 foot = 0.3048 meter).
8. Use earth curvature corrections (optional)
Allows correction for
the earth's curvature.
·
Unchecked—No curvature correction will be applied. This is the
default.
·
Checked—Curvature correction will be applied.
9. Refractivity coefficient (optional)
Coefficient of the refraction of visible light
in air.
The default value is 0.13.
10. Surface offset (optional)
This value indicates a vertical distance to be
added to the z-value of each cell as it is considered for visibility. It should
be a positive integer or floating-point value.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field OFFSETB is used if
it exists in the input observer features attribute table. You may overwrite it
by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to 0.
11. Observer elevation (optional)
This value is used to define the surface
elevations of the observer points or vertices.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field SPOT is used if it
exists in the input observer features attribute table. You may overwrite it by
specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it will be estimated through bilinear interpolation with the surface elevation values in the neighboring cells of the observer location.
12. Observer offset (optional)
This value indicates a vertical distance to be
added to the observer elevation. It should be a positive integer or
floating-point value.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field OFFSETA is used if
it exists in the input observer features attribute table. You may overwrite it
by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to 1.
13. Inner radius (optional)
This value defines the start distance from which
visibility is determined. Cells closer than this distance are not visible in
the output but can still block visibility of the cells between inner radius and
outer radius.
It can be a positive or negative integer or
floating point value. If it is a positive value, then it is interpreted as
three-dimensional, line-of-sight distance. If it is a negative value, then it
is interpreted as two-dimensional planimetric distance.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field RADIUS1 is used if
it exists in the input observer features attribute table. You may overwrite it
by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to 0.
14. Outer radius (optional)
This value defines the maximum distance from
which visibility is determined. Cells beyond this distance are excluded from
the analysis.
It can be a positive or negative integer or
floating point value. If it is a positive value, then it is interpreted as
three-dimensional, line-of-sight distance. If it is a negative value, then it
is interpreted as two-dimensional planimetric distance.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field RADIUS2 is used if
it exists in the input observer features attribute table. You may overwrite it
by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to infinity.
15. Horizontal start angle (optional)
This value defines the start angle of the
horizontal scan range. The value should be specified in degrees from 0 to 360,
either as integer or floating point, with 0 oriented to north. The default
value is 0.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field AZIMUTH1 is used
if it exists in the input observer features attribute table. You may overwrite
it by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to 0.
16. Horizontal end angle (optional)
This value defines the end angle of the
horizontal scan range. The value should be specified in degrees from 0 to 360,
either as integer or floating point, with 0 oriented to north. The default
value is 360.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field AZIMUTH2 is used
if it exists in the input observer features attribute table. You may overwrite
it by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to 360.
17. Vertical upper angle (optional)
This value defines the upper vertical angle
limit of the scan relative to the horizontal plane. The value is specified in
degrees, and can be integer or floating point. The allowed range is from above
-90 up to and including 90.
The value for this parameter must be greater
than the Vertical Lower Angle parameter.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field VERT1 is used if
it exists in the input observer features attribute table. You may overwrite it
by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to 90.
18. Vertical lower angle (optional)
This value defines the lower vertical angle
limit of the scan relative to the horizontal plane. The value is specified in
degrees, and can be integer or floating point. The allowed range is from -90 up
to (but not including) 90.
The value for this parameter must be less than
the Vertical Upper Angle parameter.
You can select a field in the input observers
dataset, or you can specify a numerical value.
By default, a numerical field VERT2 is used if
it exists in the input observer features attribute table. You may overwrite it
by specifying another numerical field or a value.
If this parameter is unspecified and the default field does not exist in the input observer features attribute table, it defaults to -90.
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