Frequently Asked Questions (FAQ)

Q: I have an Isis® file with navigation in lat/long. I need to convert the nav to UTMs. Can this be done in playback mode?

Previous versions of Isis® could convert nav from latitude and longitude to UTM in real-time only. Now you can convert to northings and eastings offline with data already written in lat/long. Once you've opened the data file in playback mode, select Record Setup from the File menu. Choose Serial Ports and then check the box for Convert Lat/Long to UTM. Next, select the Setup UTMs button and enter the correct parameters for your UTM zone, semi-major axis and flattening.(Note: the default values are for the International Spheroid on 3deg E). When the dialog box comes up, you can do a test conversion by entering values for latitude and longitude and then clicking the Test>> button to convert to UTM values.

Q: I have some really bad navigation in my data, and when I play back the lines in Coverage TritonMap™, the navigation display looks corrupted. Can I use the data?

If the navigation data contains bad positions (for example a large percentage of zeros), Coverage TritonMap™ will initially try to plot them all. This can lead to a garbled display. If you look carefully at the plot, you will find the file name. Use this as a reference and draw a box around it. Then use the "zoom" function in Coverage TritonMap™ as many times as necessary until you have the good points of your data displayed. Next, use the Eliminate Outside Points command to remove all the positions outside the box. You can then use Save Coverage Points to save the good points to text file, smoothing the navigation as usual prior to mosaicking.

Q: I use a large format plotter, such as the HP 750 or HP 755. I often receive messages such as "out of memory" and "unable to write to the printer spool file" when printing from TritonMap™.

Printing large bitmaps such as those generated by TritonMap™ (and other applications) requires large amounts of memory in the printer. It also requires enough space on the hard drive for both the Windows 95 swap file (or Windows NT page file) and the printer spool file. It is not possible to have the printer spool file anywhere other than on the "c:\" drive (a limitation of the Windows 95 and Windows NT operating systems). To overcome this limitation, try the following.

Examine the "c:\" drive of your PC carefully and remove all unnecessary files (look especially in the root). On Triton machines, the "c:\" drive should contain only the Windows 95 or Windows NT operating system.
Move the swap file from the "c:\" drive to the "d:\" drive, and then:
- If you use Windows 9x: Choose Start |> Settings |> Control Panel |> System |> Performance |> Virtual Memory and Specify my own virtual memory settings.
- If you use Windows NT 4.0: Choose Start |> Settings |> Control Panel |> System |> Performance |> Change.
In the printer driver itself, select "Use Computer Memory" (a side effect: printing goes slower).
If the printer is network-capable (such as the HP 755CM), try printing across the network.

Q: We recently purchased a sub-bottom profiler and would like to record sub-bottom and sidescan sonar data simultaneously with our Isis® system. Is this possible, and how do we go about doing it?

Isis® Sonar™ can synchronously record the Sub Bottom Profiler Data to a channel in the .XTF file along with the Side Scan data. If the data needs to be in the SEGY format then the Sub Bottom data can be extracted and converted using Triton's XTF2SEGY converter.

Q: Can I have a negative layback in Isis®?

Yes, Isis® can work with negative layback values. However, it would be better to arrange for such navigation offsets to be handled by the navigation computer at the time that the data are recorded. Also, consider moving the GPS antenna forward, if the fish really is ahead of the Navigation Antenna it might be possible to place it right above the towfish reducing the offsets to zero, thereby increasing the positioning accuracy.

Q: Can I create an ASCII file from the Target utility of Isis®?

Yes, you can create a database of all saved targets in Isis®. Report text is now formattable to any standard spreadsheet program such as Excel or Lotus 1-2-3. After saving individual contacts in an Isis® file (and while they are displayed on-screen), from the main menu choose File |> Print ASCII Report. In the dialog box, you can customize your database by selecting which fields to include (such as time, ping number, depth, etc.). You can also select the separator for the delimited file. The file is saved to the current work directory, can be imported directly into TritonMap™, and is displayed as an overlay of the mosaic when that file is opened in TritonMap™.

Q: I need to know how my Isis® was configured for a survey done over a year ago. Is there a way to recover this information?

Isis® continuously saves information from all sessions to a log file called SURVEY.LOG. The file can be found in the root directory of the drive on which Isis® is installed. SURVEY.LOG is an ASCII text file, so it can be read in WordPad or NotePad. The file contains many types of information that you might want to recall at a later date. For example, the dated file shows what version of Isis® was used, which sonar was used, COM port settings, navigation offsets, names of files saved during the session, what targets were saved, etc. If you have questions about a particular survey, the SURVEY.LOG file is a great resource for finding the answers.

Q: When I am mosaicking my sidescan sonar data in Isis® using the Mosaic option in Coverage TritonMap™, how do I decide which projection to use?

This information should be provided by the contractor or surveyor on the vessel, and you should make sure that you have agreed on which projection is going to be used before starting the survey. If you are unsure, select the following options.

UTM Projection
Northern or Southern hemisphere (as appropriate)
the UTM zone that covers the longitude of your survey area
the WGS(84) datum

This information is saved with the mosaic files and can be displayed later in TritonMap™ by clicking on the Project |> View |> Information buttons in TritonMap™

Q: Why doesn't the three-dimensional Bathymetric display in Isis® look like the actual bottom of the survey area?

We are often asked this question. Users might survey an area that has a wall in it, and then ask why the wall looks like a slope. The answer is that the 3-D Bathymetric wasn't meant to be a rendering of the actual bottom; it was designed as a quality control for qualitative examination of the data. The returned beams are plotted onto a square grid that is not rectified to reflect actual dimensions of the bottom. While such a rendering is, of course, possible, the demands of real-time processing would mean that other crucial tasks would be substantially slowed. When you need a careful rendering, view all of your data mosaicked in TritonMap™.

Follow-up. The latest versions of Isis® have a "true 3D" display feature which takes advantage of higher performance processors and graphics cards to give a far more "realistic" view of the bottom topography

Q: We're going to be performing a survey using Isis®, a multibeam/sidescan transducer, and an additional towed sidescan sonar. Is it possible to record survey data from these systems simultaneously in Isis®?

Isis® does have the capability to record data from both systems during a single session, but we recommend running two sessions of Isis® simultaneously. Each session must have dedicated serial ports assigned to it. The session that records the multibeam/sidescan data requires the serial bathy data, heave, pitch, roll, vessel heading, and vessel position. The session that records the side scansonar data uses the DSP board for the analog SSS data and receives the towfish coordinates (northings and eastings) derived from the acoustic tracking system.

If there is no acoustic tracking system, Isis® can calculate the fish position based on a combination of either: the vessel's course made good plus a manually entered layback, or the vessel's course made good plus cable counter data. Although Isis® is capable of recording data from both systems using one session, this might create several problems. Not only could depth and altitude information be associated with the wrong transducer, but positioning information would be different for the two separate transducers.

Q: Typically, our surveys extend over multiple days. Is it possible to display the trackline and swath coverage of our survey from previous days?

Yes, use Coverage TritonMap™ from the Tools menu in Isis®. Coverage TritonMap™ shows tracklines for multibeam and/or sidescan sonar, and the information can be saved as an ASCII text file for later review. Opening a previously saved ASCII file in Coverage TritonMap™ will display the tracklines and coverage from those days.

Q: We collected our sonar data with lat/long navigation based on the WGS 84 projection. Is it possible to create our mosaic in our local grid coordinates?

Yes. The Coverage TritonMap™ and Mosaic feature in Isis® includes a comprehensive list of input and output projection settings, such as state plane in both NAD 27 and NAD 83. In order to convert your WGS 84 data to local coordinates on your mosaic, from the Isis® main menu choose Tools |> Coverage TritonMap™ |> Set Delph Mosaic TritonMap™ Bounds; choose Change next to the output projection and select the option for your locale. Both input and output projections can be selected in this fashion.

Q: I would like to increase the refresh rate of my Isis® display. What resolution and refresh rates are normally supported by the Isis® hardware?

The normal configuration is 1280x1024 with a refresh rate of 60Hz. Very few monitors will support a refresh rate higher than 60Hz at this resolution. If you find this refresh rate too low, you will need to reduce the resolution of your display to 1152x864. This will enable a refresh rate of 70Hz to be supported.

Q: When I try to import a background .TIF image into TritonMap™ I get a message "LZW Locked"

LZW is a licenced compression method that is not supported by TritonMap™. You need to load the image into another graphics program and resave it as a uncompressed .TIF A very easy to use and free program is available at Here

Q: When I try to import a background .TIF image into TritonMap™ it crashes with an "Invalid Page Fault" error.

Certain types of .TIF image contain alpha layers, TritonMap™ cannot read these images. These are .TIF images generated for example by ERDAS Viewfinder, you can download ERDAS viewfinder Here You will need to resave the image as a single layer .TIF

Q: Why do I get the message, "Isis® software sentinel not found"?

This message occurs under the following conditions:

You do not have a properly programmed sentinel attached to the printer port of your system. Solution: Contact Triton.
You have a sentinel attached, but it has been damaged. Solution: Contact Triton.
You are running Windows NT or Windows 2000, and a sentinel driver has not been installed. Solution: Install the sentinel driver that is supplied on the release CD, or go to our FTP site and download SENTINEL.ZIP from the Drivers folder.
You have a printer such as an EPC 1086, Alden, TDU or any of the plotters listed in the Isis® software, and the power is not applied to the printer. Solution: Turn on the power to the printer. It seems that some printers can "hang up" the LPT1 signal lines, preventing the sentinel from being read correctly.

Note: Even if you do not have a sentinel, you can play back the "demo files" that are supplied by Triton on the release CD. However, you will not be able to play back other files, or record data, if you do not have a sentinel.

For further questions, contact technical support