Triton Isis - Manual (Page 184)

June 2004 Isis® Sonar User's Manual, Volume1 170
4. Replay the line you wish to mosaic.
The coverage map starts to fill, showing which line has been replayed.
No mosaic data is being written at this time. While this happening, you
can use the TVG menu to find the settings that give the best imagery
results in the Isis waterfall display. At this time you may also want to
verify that the bottom has been tracked correctly. If you need to re-track
the fish altitude, you should consult the “Bottom Track and TVG” section,
10.7.2.
5. After a line has been replayed, you can save the navigation data using
the File→Save Coverage Points option. This file is an editable ASCII
text file.
Smooth the navigation data
1. After a line has been displayed in the Coverage map and mosaic
window, click Nav.
2. Click Smooth Navigation and select a suitable speed range and
number of points to smooth. The speed settings refer to instantaneous
speed values, so even though the vessel’s speed may have been only 5
knots, the actual speed between navigation fixes may be much higher
due to navigation instability. This is especially true if the fish position was
derived from a fish-tracking system such as Trackpoint or Simrad HPR.
For those cases, try some different values.
3. You can experiment with different smoothing and speed settings by
clicking Unsmooth, which returns the data to its original state. You can
also use the zoom functions from the zoom window to inspect the results
more closely. After you are satisfied with the displayed navigation, click
Close in the Smooth Navigation window.
A dialog box opens and asks if you want to lock the coverage map.
4. Answer Yes unless you need to add more lines at this time. If you wish,
you can save the smoothed data as another ASCII text file.
5. If you need to apply or modify the layback in the file, click More options,
check the Apply Layback to nav in mosaic, then click setup. This
displays the standard Isis layback dialog box.
At this point the file is positioned at the end of the data.
When you have all the navigation the way you want it --
smoothed, laid back, etc., click on
Zoom-->Best Fit in the Isis
Coverage Window main menu. Also, pause the data by hitting
the space bar when the end of the file has been reached.
Chapter 9: Using the Tools Menu