Multibeam Classification FAQs (2)

QTC MULTIVIEW™

1. What options are necessary to process data from Reson 8101 and 8125?
2. What hardware is required?
3. What components of the multibeam data does it process?
4. Is it the same as QTC IMPACT™?
5. I am intending to use a Reson Seabat 8125 for mapping, the footprint at nadir position of this system will be about 19 cm by 8cm. Will QTC MULTIVIEW™ be affected by this small insonified area, or does it do some averaging prior to classification?
6. The multibeam system has a swath of 4 times the depth. Is this a problem?
7. In an area where there are boulders of 0.5 meters wide and steep slopes, will the program have problems?
8. I am using QTC MULTIVIEW and Caris HIPS/SIPS. When I attempt to import Caris reject flags, the error message "HIPS Data set mismatch; not Simrad" occurs.
9. I am using Caris HIPS/SIPS 5.3. When I import Caris reject flags, the processing box reports a high percentage of "HDCS profiles not found."
10. Does QTC MULTIVIEW process backscatter mosaics?
11. What is the grazing angle?

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A 1. The RESON multibeam system must have Option 33 (sidescan option) installed.

A 2. There is no hardware required or included. QTC MULTIVIEW™ is software only. However there are some recommended computer specifications for this software.

A 3. The multibeam backscatter images are processed. The waveforms are not processed.

A 4. No. QTC IMPACT™ is for single beam echo sounder data and processes raw waveform data. However, the final processing steps for classification are the same in QTC IMPACT™ and QTC MULTIVIEW™.

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A 5. Our classification relies on analyses of rectangular patches which are spread across the image like a quilt. Each side of a rectangle has to be 2 ⁿ +1 pixels long and minimum 9, thus 9, 17, 33, 65 ... . You can choose the rectangle size to fit your situation. In any analysis, all the rectangles have to be the same size. They can overlap or have spaces between them (please contact us to find out how to do this).

If you have the the sidescan option for your 8125, you can have spatial resolution as small as 9 x 9 image pixels. This may be a very small area. You may want to choose 9 pixels along track and a larger number across track. With this option, you would have a wide choice of spatial resolution.

A 6. No. Swath width being 4 times depth is quite normal with respect to multibeam systems.

A 7. Provided your multibeam system accurately resolves the depths along the slope, our grazing angle compensation routines should very adequately deal with the situation. This means that the multibeam needs to provide a series of depths along the slope, no just the top and the bottom for example. It is expected that the system would do this, so there should not be a significant problem. Our research team has spent a lot of time overcoming problems relating to range, depths / grazing angle, and are confident that we can provide good results in a region of such significant relief.

A 8. This is a known issue. There are two options. Upgrade to the most current release of QTC MULTIVIEW or reload the data with Caris HIPS/SIPS 5.2.

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A 9. This is a known issue. Caris HIPS/SIPS 5.3 and subsequent versions have removed a necessary file (the TAI-UTC file). Click here to download this file. Create a Config directory in the HDCS_Data directory and place the TAI-UTC file into that Config directory. This file does not have an extension so make sure that your browser has not added an extension.

A 10. No. Mosaics often have along track artifacts and decreased resolution and this would negatively impact the seabed classification. Also, if we used a mosaic, we would be unable to do any quality control based on beam quality or compensation based on survey geometry. Instead, we run our backscatter image analysis algorithms on each line individually. After the algorithms are run, the lines are merged together and the clustering process, which determines the acoustic classes, is run on the entire data set.

A 11. Grazing angle is equal to 90° minus the angle of incidence. For the beam shown in the following figure, the angle of incidence is the angle between the beam and the tangent normal. The grazing angle is the smallest angle between the beam and the tangent plane.

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