Documenting an overhang

Third Party Products Sonar and Acoustics
1

Hello. I’m trying to document an overhang in a rock cut underwater with a BlueBoat. I have received data from the sonar (via CSV) and I have data on land. My problem is that I can’t get anything other than SVLOG files out of the Omniscan 450. Is there any way I can create a point cloud from this data?

pictures show data I have now.

image
image1920×1021 186 KB

1 Like
2

Omniscan 450 is a sidescan so as such it has slant range information only but not the vertical angle. Therefore you can’t get a 3d point cloud from sidescan data.

You might be interested in the upcoming Surveyor 240-16 MBES – ceruleansonar, a multibeam sounder which does output a point cloud. Shipping end of June.

Larry

3

Hello. It is of great interest, and I look forward to its availability.
But at the moment it can’t help me with the task I’m trying to solve.

What is my biggest problem now is that I cannot convert the SVLOG files to XTF. I have only tried with Windows as operating system. Do you know if the export from SVLOG to XTF works in SonarView on other operating systems? Are there other programs that can convert SVLOG into something that can be used to visualize the rock carving underwater?

I can give access to the SVLOG files via googledrive or Teams, if someone can help me quite quickly.

David

4

Hi @Dande83 -
Unfortunately it is fundamentally not possible to create a 3D point cloud from side-scan data. Sorry for the news!

5

I have data from the total station which is shown as cyan superimposed on the sidescan. Is it really 10 meters overhang, or am I the one who is interpreting the data completely wrong? I don’t necessarily need a point cloud but need to know if that is the case…

image
image1773×1202 173 KB

6

Hi @Dande83 -
By overhang, are you referring to the black band along the center of the side-scan data, before the gold texture? This is not an overhang, but just the way sidescan data typically looks! You can think of the image produced as what you might see if you shone a flashlight from the boat towards the bottom at a nearly horizontal angle. Items that stick up from the bottom cast a shadow behind them, that can give a rough idea of heigh and size of objects or bottom surface texture.

Side Scan Sonar - 600 kHz
Side Scan Sonar - 600 kHz800×690 481 KB

As Larry mentioned, you only have the slant range information, so that is why reconstructing a 3D point cloud is not possible… to me your data looks like a textured bottom surface?
This guide may be helpful in unerstanding it more, or the wikipedia article.

7

SonarView/Omniscan does have an XTF export which effectively converts the svlog file to XTF. If your SonarView doesn’t have that you should update to the latest release. If you have any problem with XTF export please let us know. We are very interested in feedback on XTF.