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Sorry can't read the yellow circle label but I would say that has to be rock on bottom, yes the bright white items are fish & yes I see their shadow & YES by the size of their shadow that tells you those fish are not on bottom but fairly high in the water column.. Good pict........... Oh yes the small circle of fish in the lower left side don't seem to producing a shadow so I would say they are pretty close to the bottom.
The yellow is the unidentified structure... Can't really tell what it is... Just curious what people think the yellow circled structure could be...
So far we have rocks as a guess.
DoubleG
OK so I got a dumb question. Sonar can read shadows? Don't think thats possible.
Help me read this. Center line, then the darkest area is vertical and the rest is horizontal?
Thanks for helping us learn something about what we have and need to learn how to use. You keep putting these oics up and helping id stuff I'll sooner or later get it... This helps me to cifer some of the stuff I see when outonwater. I did recognize the fish on the left, but didn't pick up on the shadows, and saw the ball of fish on lower left, still figure the yellow is rocks or something like that. Question, where are the shadows of the fish on the right side? I figured they were part of what you see on the left.Quote:
Originally Posted by DoubleGobble00
It looks like bream beds to me.
I'm gonna go out on a limb and say Dd's been there and a blue paper towel moment struck and the remnants have settled and the catfesh are circlin like buzzards.
I copied this response Doug Vahrenberg placed on the BBC forum to help you understand side imaging. Yes, those are shadows. The SI works differently from 2D sonar. SI are thin beams of sound waves uses to scan the area. Maybe his explanation will help...
Here is an easy way to understand Side Imaging. Get a flash light and hold it to your side (slightly downward) turn off the lights in the room. Now point it at something. Like a leg of a chair to represent a tree or bridge piling.
Now Think of the light from the flashlight as the sonar beam. When it hits the leg of the chair it does not go through it but creates a shadow. If the light was SI sound wave it does a similar situation when the soundwave hits the piling the sound wave is returned to the transducer. Since sonar cannot travel through mass easily trees, fish, rocks etc it is reflected back to the transducer, in Side Imaging since the sound wave is returned it creates a shadow. Past the piling or like the light did in the chair leg. Same thing if you point it at the back of your hand the light won't iluminate the palm of your hand. This same thing happens in 2D sonar but it is shooting straight down. Point the flshlight straight at the ground.
If we look at this image as traditonal downlooking sonar and more in turns of dual beam sonar like HUmminbird uses. The red inner circle is the 20° cone. And the outer Yellow circle is the 60° cone. THe like expands in a cone shape - it gets bigger. Now the coins I've layed on the floor represent suspended fish lets say. THe reason 2D sonar can return multiple layers in a single vertical pixel layer is that it is getting return information from each ping from several areas in the circle. Say the three cones in the inner red circle are 1 foot ,3 foot and 5 foot off the bottom in ten foot of water it would light those corresponding pixels at the distance the sound beam travelled . It can also record the bottom since it was returned uninterupted sonar waves from else where in the circle like the dead middle. Now the benefit of Dual beam sonar is the added coverage area represented by the outer circle(yellow) 3 more coins or fish where detected in this circle. The 60 degree beam would have detected a total of 6 fish plus depth in single sonar ping.
Now we have to explain SI is not like traditional sonar it only uses the most intense part of the beam - similar to an MRI in the medical field. I represent this by taping off part of the flashlight beam.
And it creates a narrow sonar beam or light beam (Hard to totally accomplish with a flashlight. It's not round like a traditional cone angle. These thin slices like 1° slivers of sonar are very powerful and can capture high levels of detail that it why the Humminbird SI units can capture great details to the sides.
This picture is similar in comparison to the slice of sonar the SI units cast.
Hope this helps explain what is happening. That is why to get high detailed images in SI you need to be moving forward. It takes small slices and connects them into picture like images. If you were sitting still it would still show something was there but the returns would be a continuous line. Just like when tou hang a dropshot over board and do not move it - it is displayed in 2D sonar as a continuous line.
I stand corrected. Thanks Zack! I would like to see the link you got this from. still trying to understand.
I bet that was hard to type wasn't it. LOLQuote:
Originally Posted by Wannabe...
I see what you guys are saying about the picture(s), the shadows mean some fish are not as deep as others, etc. Youz guyz is smart !!!!