Sonar Files to 3D XYZ files

Official Firmware, Side Image Viewers, Map Overlays, 3rd Party Apps, etc..
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agt
Posts: 8
Joined: Thu Feb 17, 2011 5:06 am

Sonar Files to 3D XYZ files

Post by agt » Thu Feb 17, 2011 5:11 am

when i purchased my hb with si i was under the impression that the sonar files that run 150ft left/right can be converted to xyz points. from these xyz points i could them make a seabed profile. when i used my sonar to export to xyz using humviewer all i get are the points immediately below the boat. it is like exporting a track file to xyz.

how do you export the sonar to get all the points left/right to have xyz values?

SilmarilS
Posts: 188
Joined: Wed Oct 14, 2009 12:19 pm
Location: Canada, QC

Post by SilmarilS » Thu Feb 17, 2011 1:40 pm

You can't.

Since SI data don't include depth readings..

Only the standard 2D sonar can provide depth data to mapping programs.
The only difference between Si and regular 2D sonar, is once you have made your bottom profile map,
some software can overlay the SI image over the map.

The only way you can have more than 1 depth data, is using a modified Matrix 47 3D sonar.
I once see this setup on the web. Seem way complicated to do!!
It will do 6 depth data point wide!

mendota
Posts: 34
Joined: Wed Feb 18, 2009 10:08 pm
Location: Madison, WI

Post by mendota » Mon Feb 28, 2011 9:29 am

The SI beam can only give you the slant range, which is the distance to a target, not the depth of the target. The only place the slant range is equal to the depth is directly under the boat.

agt
Posts: 8
Joined: Thu Feb 17, 2011 5:06 am

Post by agt » Mon Feb 28, 2011 5:02 pm

mendota

hello. by slant range do you mean slant distance? if it is a slant distance then it is just a matter of trigonometry to get the depth to the sides of the boat. even hb forums have no mention of how to get the depths from the si images.

it seems such a waste of si data if they are just going to throw them away unprocessed.

mendota
Posts: 34
Joined: Wed Feb 18, 2009 10:08 pm
Location: Madison, WI

Post by mendota » Mon Feb 28, 2011 5:45 pm

Slant range is the straight-line distance from the transducer to the target. (the sea floor, in your case)

You can only calculate the depth if you assume the bottom is flat. If there is any unknown slope, which of course is the whole point of mapping, the calculation is garbage.

agt
Posts: 8
Joined: Thu Feb 17, 2011 5:06 am

Post by agt » Wed Mar 02, 2011 7:29 pm

mendota

based on the description for the hb798ci the side imaging images have horizontal distance left/right for a max of 45 ft.

if you also have the slant distance from the transducer then simple trigonometry would result in the depth of the point. from the little that i know about sonar, distance data is the primary reason for using sonar in marine applications.

i think it is more of an accuracy issue that is holding back hb from releasing this 3rd dimension data.

SilmarilS
Posts: 188
Joined: Wed Oct 14, 2009 12:19 pm
Location: Canada, QC

Post by SilmarilS » Thu Mar 03, 2011 2:46 am

What you need for your application is a MULTIBEAM sonar.

This will give you multiple data points on each pass.

But these systems are not for private users as they cost as much as a house!

agt
Posts: 8
Joined: Thu Feb 17, 2011 5:06 am

Post by agt » Thu Mar 03, 2011 7:34 pm

simarils

yeah that is what i was saving up for but the price is just too high for my purpose. when i saw the brochure for the hb with si i believed that it was a scaled down version for a sidescan sonar. they just renamed it to side imaging for their branding purposes.

since i saw that you could save sonar data then i thought that it was just a matter of converting them to 3d terrain files.

UlfE
Posts: 19
Joined: Sat Mar 05, 2011 7:59 am

Post by UlfE » Sat Mar 05, 2011 12:14 pm

agt wrote:simarils
when i saw the brochure for the hb with si i believed that it was a scaled down version for a sidescan sonar. they just renamed it to side imaging for their branding purposes.

since i saw that you could save sonar data then i thought that it was just a matter of converting them to 3d terrain files.
A side scan sonar emits a fan-shaped beam of sound. A multibeam echo-sounder emits many narrow beams of sound.

What you can do is to run many profiles and use a geo-interpolating software to create a depth map. That's how everyone, including surveying experts, are doing - with the only exception of those who use a multibeam echo-sounder.

The side scan sonograph is not wasted, though; it can tell you if there are obstacles between your sounding lines. That replaces the need for physical depth control with a towed bar, as one had to do before the advent of these new instruments.

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