TAP™ licenses including the 3DDisplay Module provide several options to improve the appearance of a path profile in Google Earth.
The baseline option to export a path profile to a KML file for Google Earth displays the line of sight and three boundaries for the Fresnel zone – directly below the line of sight path, and to the left and right of the line of sight path:
HDPath allows you to create a mesh to display the entire Fresnel zone region to better visualize the effect of obstructions along the path:
This more complete representation of the Fresnel zone gives you more flexibility to explore and display the effect of obstructions on the path.
(Note that the reason the Fresnel zone in these images appears elliptical rather than circular is because the Google Earth Tools, Options menu was set to set the “Elevation Exaggeration” to a factor of 3 to provide more definition of the terrain features. The vertical dimension of the Fresnel zone is stretched to match that exaggeration.)
Note that since the image from the new version is more complex it will take longer to create. A message will be displayed during the process:
Setting Fresnel Lines
To use the function to draw additional lines for the Fresnel zone around the line of sight, click the “Configuration” menu in HDPath, then click “Google Earth”, then select “Fresnel Angles”
A form will be displayed to specify the starting and stopping angles where Fresnel zone lines will be drawn around the line of sight, and the step, or increment, between those lines:
(The angle around the line of sight is the angle looking at the transmitter from the receiver end, incrementing clockwise.)
The Fresnel zone can also be drawn as a “mesh” by checking the “Fresnel mesh” item in the “Configuration|Google Earth” menu.
Without the “mesh” effect, only the Fresnel lines are drawn:
Adding the mesh provides further definition for the Fresnel zone around the line of sight:
Setting Earth Curvature Display
An adjustment in the display of the earth curvature must be made to export the path profile to the KML file for use in Google Earth.
You can mark the “Always bend LOS and Fresnel” option in the Configuration menu to eliminate that message.
Setting View Angle
In the earlier version the path was drawn and the initial viewing angle in Google Earth was above the path, with the map oriented normally with north at the top:
You can use the Google Earth zoom, rotate, and tilt controls to change the view of the path.
In the current version, you can select two other viewing angles, from the Transmitter to the Receiver, or the reverse path. Under the Configuration menu, click Google Earth, then “Initial View Location” and the desired view:
This gives a starting point for using the tilt, zoom, and pan functions in Google Earth.