Triton XTF side scan data import
Since Hydromagic Survey version 9.1, it is possible to import side scan sonar data from XTF files. XTF stands for eXtended Triton Format and is a file format which is widely used to store bathymetric data, like single beam soundings, side scan data and multi beam bathymetry.
Before you import side scan data, make sure a project has been created or loaded with the correct map projection. If the map projection isn't suitable for the selected side scan data files, the import process will result in distorted images.
To start the side scan data import wizard, locate the 'Sidescan Files' folder in the 'Project Explorer' and right-click the folder. From the context menu that appears, select the 'Import Data Wizard...' option as shown in the screenshot below:
Select the "Import Data Wizard..." option to import side scan data
into your Hydromagic Survey project.
Select the correct side scan data file format
Hydromagic is able to import various side scan data formats, including:
- Triton XTF side scan data files;
- Humminbird side scan data files;
- Lowrance side scan data files.
To import side scan data from a Triton XTF file, we select the "Triton eXtended Format Files (*.xtf)" option in the first page of the data import wizard. Once selected, click the 'Next' button to continue to the next page where we will select the files to be imported.
Select the "Triton eXtended Format Files (*.xtf)" option from the drop down list.
Selecting sonar files
To select the files to import, you must choose the folder where they are copied. This can be done by clicking the "Browse..." button. After selecting the folder, click "OK", and Hydromagic will automatically scan for Triton XTF files and shows them in the list:
Select the files to be imported by checking the check boxes.
Select the files you wish to import into your Hydromagic Survey project by checking the check boxes in front of the file names. To import all files at once, simply click the "Select All" button. Once the selection is complete, click the 'Next' button to go to the next page of the wizard where we will adjust the import settings.
Triton XTF Import Options
Please take some time to review the settings in the "side scan Import Options" page. Once set correctly, the values will be stored for the next time you use the wizard. Especially the sound velocity setting is imported, since an incorrect setting may cause objects to display closer or further from the vessel then they are.
Sound Velocity
The sound velocity is needed to calculate the range from the number of samples. Using an invalid range can cause objects to appear closer or further from the vessel then they are actually are. Depending on the selected units, you have to specify the sound velocity in either meters per second or feet per second. When unsure, use the default 1500 meters per second value. When the sound velocity is set to 1500 meters per second, the sound velocity value stored in the XTF file will be used instead. Any other value will override the sound velocity value stored in the file.
Limit return samples
Use this option to specify the number of return signal samples will be processed by the software. You can use this setting to avoid overlapping side scan images. When a value of zero has been entered, this setting will be ignored and all samples are processed and converted to image pixels.
side scan data filter
The filter can be used to filter noise from the side scan data. A couple of filters can be selected to process the data:
- Smoothing Mean;
- Smoothing Gaussian;
- Smoothing Median;
Feel free to experiment with the filter setting to see what is working the best for your data. When you want to make sure objects aren't affected by filtering, select the "Disabled" option. This will cause the wizard to skip data filtering when importing side scan data.
side scan data clipping
With the clipping option, you can select a boundary to clip the resulting side scan image overlay. All pixels not within the boundary won't be calculated. Click the "Select..." button to select one or more (islands can be defined) boundaries, or ignore this setting to import all data.
The "side scan Import Options" page can be used to customize some settings
before importing side scan data.
Adjust Gain Settings
For some files, additional gain settings need to be set to get the same color intensity for pixels as the distance from the nadir increases. You can set a time varying gain (10logR, 20logR, 30logR or 40logR) to compensate spreading loss, as well as a correction factor for attenuation of return signals due to sound absorption in the water.
Since both unprocessed and processed data from various brands of side scan sonar equipment can be stored in XTF files, the ideal setting will differ from file to file. You might need to experiment with the different settings. To calculate the theoretical sound absorption in decibel per meter, you can click "Calculate..." to launch the sound absorption calculator. You need to copy and paste the decibel per meter value into the wizard.
After adjusting the gain settings, please click "Next" to go to the last page of this wizard.
The gain settings can be used to correct the side scan image for
spreading and sound absorption losses.
The "Sound Absorption Calculator" can be
used to calculate the attenuation value.
Starting the import process
After selecting the data format, files, import and gain settings, you can click "Finish" to start the import process. A progress window will show the importing progress of for the selected side scan files. In case of problems, make sure you always check the "Processing" tab of the real time activity view pane.
Click the "Finish" button of the last wizard page to start the data import.
Once all files have been processed, they will appear in the project manager and as map overlays in the map display window. To change the color schema for the images, right-click the 'Sidescan Files' folder in the 'Project Manager' and select the 'Sidescan Options...' menu item.
A progress window will show the progress of the importing process.
Video Tutorial
The following YouTube video tutorial shows how to import XTF sonar files as side scan images in Hydromagic. Click below to play the video. When you like the video, please click the like button and subscribe so you will receive an update when new video tutorials on Hydromagic are uploaded.
The following YouTube video tutorial shows how to import XTF sonar files.