2.6.6DEM Plotting

The methods of interpolation supported by GrafNav

Linear

This interpolation model is the simpler of the two and gives no RMS statistics. It fits a line between the two nearest epochs and places the camera mark on it. It is simple but effective.

Polynomial

This method uses a 2nd order polynomial and gives the best accuracies, but it can sometimes induce larger errors if epochs are missed or dynamics are very high. This can be detected by viewing the RMS value computed for each camera pulse. To do this follow these steps:

1.Click on the station or write the coordinates.

2.Select Features and use no geoid correction.

In such cases, the linear interpolation model deliver better results. You can also change the size of the window that the polynomial fits into. Ideally, this number should be kept at 4, but it can be increased for more averaging.

Only use this when very high data rates are available.

2.6.7Photogrammetry

These options are useful to GrafNav for GPSassisted aero-triangulation. This includes control over how interpolation is implemented.

Camera Pulse Interpolation

These options determine how the camera marks are interpolated. See Section 2.3.10, on Page 41 for help loading camera marks. Since each photograph is seldom taken on the even epoch, it must be interpolated to compute a proper position. Two methods of interpolation supported by GrafNav are listed in the shaded box.

Photogrammetric Strip Processing

This option is no longer supported by the software.

Apply 3-D Offset

Lets you apply a 3-dimensional offset from the antenna to the measurement device (entry nodal point on aerial camera). The offset is defined in the local body system of the aircraft, and not the camera. See Section 2.7.4, on Page 111 for more information.

Load Settings From

This feature loads configuration settings from one of the following:

•Factory Defaults: Built-in default settings (cannot be altered).

•GrafNav Defaults: Start-up settings that can be altered. Otherwise, same as Factory Defaults.

•Pre-loaded Profiles (for example, Airborne,

Low Cost, Tree Cover, and so on.): These are settings that come pre-loaded with the software.

•User-created Profiles: These are profiles that have been created by you.

When using a profile, all processing settings can potentially be edited, except those found in the Process tab. See Process on Page 61 for help with these settings.

Coordinates for Display

Geographic

Displays the latitude and longitude on the screen. The orientation is such that the positive y-axis is true north.

Local level

Shows the vector difference between the master and remote. It is most useful for GrafMov where you can see the relative separation rather than the absolute position, which tends to be less meaningful.

Grid

Displays the coordinates in the grid selected under

Settings | Grid.

The UTM zone has not been set. In such a case, the display may be severely rotated. Be sure to set the zone correctly. See Section 2.6.5, on Page 97 for help.

Map/distance units

Changes the units of the values being displayed for local level or grid coordinates in the Map Window. Changes the units displayed when using the Distance & Azimuth tool as well. See Section 2.8.2, on Page 129 for information.

2.6.10Preferences

Display

This option allows you to edit the Map Window display and other preferences.

General

The following settings are available:

Zoom increment scale factor

The default is 3, although you can change this to any positive integer.

Use H:M:S m/d/y for default time system

Encourages GrafNav to display time in the described format instead of seconds of the GPS week.

Show direction arrows on trajectory

Shows arrows in the direction of travel on the map screen.

Show grid lines in map window

Displays grid lines.

Show legend at bottom of map window

Toggles the display of the color-coded quality numbers legend.

Draw White background instead of black

Changes the background colour of the Map Window from black to white.

Coordinates for Display

The settings are listed in the shaded box.

Zoom Level Specific

This set of options is based on the Zoom Level specified.

Zoom Level

Level 0 is the main screen without being zoomed. Each level has its own set of default display options that can be changed to your preferences.

Text Display

Controls the font size. The Show Text option allows text to be seen on the screen.

Symbol Size

Controls the symbol display.

Static Sessions (MB only)

You can choose whether to plot the static session lines to all base stations, to the nearest base station, or not to draw any lines at all.

Solution

Combine Settings

The following settings are available:

Automatically load solution on project start

Loads the FWD and REV files into the project once a CFG file is opened.

Combine forward/reverse after successful processing

Automatically loads the combined solution into the project after processing forward or reverse direction. A combined solution is always loaded after processing both directions.

Automatically write.CMB file after processing

Writes a CMB file after processing.

This slows down the CPU response after processing if a large project has been processed.

Processing

Enhanced processing is available with dual processors. The options are listed in the shaded box.

Float Static Tolerance

Allows you to configure the equation used to determine whether a float static solution passes or fails. If you are a Seismic use, you might want to raise this tolerance to limit the number of failing sessions.

Processing Options

Process forward/reverse directions simultaneously

This feature cuts dual CPU processing time in half and improves dual core machine processing by roughly 2030% because the software processes the forward and reverse directions at the same time. With one processor, avoid using this option because it is faster to process each direction sequentially.

Issue audible warnings (beeps) during processing

Certain events result in a sound effect being played. This option allows you to turn these sounds effects on or off.

When finished processing

Notify user with a prompt: Displays a message at the center of the screen once processing is complete. When disabled, you will hear a beep after processing, unless an error occurs.

Close processing window(s): Closes all processing windows after completion.

Display group of plots: If you have defined a group of plots under Output | Plot Results, then you may select it here for automatic display. See Section 2.7.1, on Page 105 for help creating a group of plots.

Export Google Earth file: The software writes a KML/ KMZ file to the HTML folder, which is located in the project folder. If the Output | Export to Google Earth | Create Auto-Update Entry option has been used, then Google Earth updates the new trajectory.