3D Analyst Tools ArcToolbox

Line Of Sight, Observer Points Tools

Line Of Sight

How to use Line Of Sight Tool in ArcToolbox ArcMap ArcGIS ??

Line Of Sight

Line Of Sight Tool, Visibility Toolset, 3D Analyst Toolbox

Line Of Sight

Determines the visibility of sight lines over obstructions consisting of a surface and an optional multipatch dataset.

1. Input Surface

The LAS dataset, raster, TIN, or terrain surface used in determining visibility.

2. Input Line Features

The line features whose first vertex defines the observation point and last vertex identifies the target location. Height of the observation and target locations are obtained from the z-values of 3D features and interpolated from the surface for 2D features.

2D lines also have a default offset of 1 added to their elevation to raise the points above the surface. If the feature has an OffsetA field, its value will be added to the height of the observation point. If the OffsetB field is present, its value will be added to the height of the target position.

3. Input Features (optional)

A multipatch feature that may define additional obstructing elements, such as buildings. Refraction options are not honored for this input.

4.    Output Feature Class

The output line feature class along which visibility has been determined. Two attribute fields are created. VisCode indicates visibility along the line, 1 being visible and 2 not visible. TarIsVis indicates the target visibility, 0 being not visible and 1 being visible.

5. Output Obstruction Point Feature Class (optional)

An optional point feature class identifying the location of the first obstruction on the observer's sight line to its target.

6. Use Curvature (optional)

Indicates whether the earth's curvature should be taken into consideration for the line-of-sight analysis. For this option to be enabled, the surface needs to have a defined spatial reference in projected coordinates with defined z-units.

· Unchecked—The earth's curvature will not be taken into consideration. This is the default.

· Checked—The earth's curvature will be taken into consideration.

7. Use Refraction (optional)

Indicates whether atmospheric refraction should be taken into consideration when generating a line of sight from a functional surface. This option does not apply if multipatch features are used.

· Unchecked—Atmospheric refraction will not be taken into consideration. This is the default.

· Checked—Atmospheric refraction

8. Refraction Factor (optional)

Provides a value to be used in the refraction factor. The default refraction factor is 0.13.

9. Pyramid Level Resolution (optional)

The z-tolerance or window-size resolution of the terrain pyramid level that will be used by this tool. The default is 0, or full resolution.

Observer Points

How to use Observer Points Tool in ArcToolbox ArcMap ArcGIS ??

Observer Points

Observer Points Tool, Visibility Toolset, 3D Analyst Toolbox

Observer Points

Identifies which observer points are visible from each raster surface location.

1. Input raster

The input surface raster.

2. Input point observer features

The point feature class that identifies the observer locations.

The maximum number of points allowed is 16.

3. Output raster

The output raster.

The output identifies exactly which observer points are visible from each raster surface location.

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. 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).

6. 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.

7. Refractivity coefficient (optional)

Coefficient of the refraction of visible light in air.

The default value is 0.13.