Topic: Down Imaging in Hummviewer?

[cweb]

Will  Down Imaging be usable in Hummviewer 44?

[mrj9600]

If you are asking whether you will be able to see a Down Imaging view in HumViewer, then the answer if no.
The Down Imaging feature on the HB is generated by the software in the HB based on the existing recordings, so unless Humminbird is willing to share with the forum how that is done, then it will be difficult to implement in the HumViewer program.

/Martin

[George]

Martin
 
Thanks for clearing this up, I was hoping the information was in the files saved.  It is what it is, hopefully at some point they will share the information but I doubt it, since they are very guarded for good reason.

George

[RGecy]

Matin,

I think it would be pretty simple to come up with a Down Imaging algorithm.  The processing will task the processor a little more, but its doable.

I think that its not much more than an average of both SI beams.  There may be some sharpening algorithms in place or sensitivity adjustments, but nothing too complicated.

Robert

[George]

Robert

With the above statement that DI is an averaging, does that mean we see directly under the boat with SideImaging?  I thought the space under the boat was a void area.

George

[mrj9600]

Matin,

I think it would be pretty simple to come up with a Down Imaging algorithm.  The processing will task the processor a little more, but its doable.

I think that its not much more than an average of both SI beams.  There may be some sharpening algorithms in place or sensitivity adjustments, but nothing too complicated.

Robert

Hi Robert
I have had the same thought. That was why I wrote difficult, and not impossible. 
I have a few new features that I will concentrate on implementing first. When they are done, I might give it a try.

/Martin

[RGecy]

George,

Yes, with SI in 455khz you are getting almost 180deg of coverage, even right below the boat.  800khz does have a gap though.  They did not have to modify the transducer because the data is already there!  Its just presented in a different way.

Here is a scan of a small 14' boat sitting on its side in 30' of water at 455khz.  Notice how the boat appears on both sides symetrically.  The only way this would happen is if I had passed directly over it.

Details Sandy Island Boat

Sandy Island Boat

[George]

Robert,

Thanks now that I looked at your picture, I have observed these on my own system.

George

[RGecy]

This was done in photoshop and basically turned the image I exported from the playback on the PC on its side.  I will post the actual DI image later tonight for comparison when I get a chance. Hmmmmm!

I need to go take my 997 out of the boat and play it back.

UPDATED: Here is the actual Down Imaging snapshot from the 997c.  I would have to say that its pretty obvious that its just an average of the two sides from the SI data. We know nothing new is being recorded since we can play back older files.  I still prefer the SI views. Its the same data, just turned sideways! And really does not have the detail that the SI view offers or ability to determine the position of the object left or right of the boat.  Its a neat feature though!  Just my two cents!

Robert

[George]

Robert

Thanks for the explanation.

Now that I think about it HB's manuals kind of tells us how to do the various functions, but I do not think we really understand what each function does.  It is like the TVG/Switch Fire, I am not sure what it actually does other then it cleans up the 2D screen in "Clear Mode" and in "Max Mode" it appears show all of the noise along with fish arches.  Does "Clear Mode" filter out the fish as well debris or feedback.  I believe Switch Fire is important but I keep going back between the two settings.

Maybe over time we can develop not just a glossary but definitions on the different functions that gives us a clear understanding, or maybe it is all there and I am just dense.

George

[Jolly Roger]

George,
I think since we or better most of us haven't used the new features and played around with the, we are all "dense" at the moment.

For me DI and Switchfire is still something I got explained and shown in pictures, so my gut feeling tells me that it's not usefull for searching for structure or wrecks. But this might change if I have used it in real life and on the water. Try and error and the experience that will follow will tell and teach us, how the features can be used and what benefit we can have from them.

Damn! Wish it would have warmed up already, 'cause I'm getting itchy and can't wait to test and play with it.

My 2 cents

Harry

[George]

Harry,

Thanks for your thoughts, there is a lot to be learned.  I expect that over the next few months we will work a lot of this out.  I have been trying some of the settings that others have used and did get some improvements.  Still working on DI and Switchfire, I can see some value in DI, but I think that Switchfire would be a lot better if they gave us a sliding scale instead of just Clear Mode and Max Mode (maybe a later update).

George

[sonar2000]

Now I am a bit confused.  I know the show and tell says 180 degrees, but I think the actual cone starting at the surface is 97 degrees for each side.  That leaves a 3 degree silent part underneath the boat or 6 degrees if you add both sides. I have notice3s that if the object we are passing over sticks up from the bottom (not lsure of the minimum height, then it will show in the silent part under the bottom.  Depth plays into the width of the area depicted as under the boat and that kinda of hols true the the cone is only 97 degrees. the deeper you go the wider the bottom silent gets. Now that is my understanding.  Greg or Marting can you guys get a litter deeper into this.  Chuck

[RGecy]

sonar2000,

You are accurate in the 6 degrees, but Humminbird has never said weather the 3 deg on each side was under the boat or at the surface.  My guess is that the margin is so minimal you will get some reflected sound waves at more than the 87 deg on each side. 

But as you state, the deeper you get the wider the gap will be.  I have done the math somewhere here on the forum and if the gap is 6 deg and your depth is the 30', the area not covered would be approx 3' wide.  That is assuming the the cone is the full 6 deg under the boat.  If Humminbird has it so that cone is 3 deg under the boat and 1.5 deg to each side, then the area not covered at 30' is 1.5'.

Hope this helps.

Robert

[sonar2000]

correct the previous statement on the 97 degrees.  that was my typo error.  That should read 86 degrees and the silent part of the cone is 4 degrees.  That is for the 455 khz selection.  I should read before I hit the post button.  Now looking at the 800 khz the cone is a 55 degree cone. I am not sure how the silent 35 degrees is distributed between the Bottom and top silent part but that will widen the bottom uncovered area a bit more.    chuck

[sonar2000]

I was uing the 1197 book on page 53 and for the 455 it shows the signal parrarel to the surface and the 4 degrees under the boat.  but then again the picture is what I am looking at and not the specs. The picture of 800 khz shows the underboat a bit clearer.  Maybe Greg can weigh in on this.  I made a chart using a right triangle to show gap at depth using 4 degrees. let me know if my understanding is not correct so I can toss the chart. chuck. 

[RGecy]

chuck,

We have discussed this topic for almost 5 years now.  I don't think even Greg knows exactly from what he has said.  If you do a search, on this forum and Craigs forum, you will find several informative topics with diagrams, charts etc.

Yes, the 800kHz has a very wide gap.  I only use 800kHz when I have found a target with 455kHz that I want better definition on.

As for the 86 or 87 deg, I have seen both in the literature.  Not sure if the original SI transducer vs the Hi-Def was slightly different and that's the reasoning for the two different numbers.

Either way with 455khz, the cone is so small, the area not covered is neglegible.

Robert