I have a feature request / tweak for the mosaic overlay. The minimum turn feature is good and I can see that you might need a max speed function in some places. But... a minimum speed would be very handy too as when you are travelling less than 1 km/h the structure scan gets smudgy.

Dan

Dannet,

the slower the speed, generally, the better. A target will receive more ensonification and a small or buried target is more likely to show. The smudging is caused by the vessels head not being stable, or not being transmitted as stable. A "point 1", or better head smoothing may help.

T

True Dan, something we should add.

Currently sidescan mosaic uses a heading derived from the course over ground - it does not use information from a heading sensor, even if one is available. This means that if you moving very slowly, or not moving at all, RM has no way of knowing which direction the SS beam is pointed, and geo-locating the sidescan return is impossible.
Generally it is required to keep travelling at a reasonable speed - a couple knots at least - to get good logs for mosaicking. I agree that a minimum speed filter would be useful here as well, so we'll look at adding in in an update.

Also bear in mind that there are other ways to edit your swath. E.g. just select the good bits in a track, using the swath control bar at the bottom of the screen and add these to a mosaic, instead of adding the whole track.

Matt

Matt wrote: I did discover this work around and given my tracks were very close together and overlapping somewhat is was necessary to do exactly that. My initial thoughts are:

• If using sidescan to make a mosaic it is very important that tracks are parallel.
• If creating a mosaic this needs to be the primary objective of your data logging where as when creating a map you can get away with just logging data as you fish.
• The screen on the HDS-7 is too small to make practical use of a mosaic overlay.
• For the reasons above I would probably not bother to make mosaic overlays.
• The tool is excellent for reviewing log files and quickly identifying structure. I located numerous submerged logs and two rock bars I did not know existed. Marking new way points for these new found structures is very quick and effective.

I am replacing my transducer though as the left channel is now shot and perhaps that may change my perspective on creating overlays. A dedicated chart plotter with the sounder on a second unit would likely improve my ability to use an overlay.

Overall though this will be a very handy tool and the limitations lie more with a small screened chart plotter and the method in which I capture data.

Dan

True providing you are actually moving in a forward direction. I find if you are stopped it gets streaky.
Dan

AnglingCharts wrote: True providing you are actually moving in a forward direction. I find if you are stopped it gets streaky.
I am not sure what you mean by "A point 1 or Better head smoothing"?
Dan

Dan, I think T means the lowrance point 1 antenna which (via a nmea 2000 network) provides position and heading from an inbuilt electronic compass. However Matt mentions that this heading is not used anyway by rm (which i think uses the vector between 2 points to produce COG). I guess the advantage of using the point 1 antenna might be more accurate positions and hence a more accurate vector between points. As you probably are aware, GPS (even with SBAS corrections) will have a slight positional error from point to point. If you are stopped, or go very slowly, essentially, this error may be magnified in the heading value, as a slight error will have a big affect on the heading over a short distance. As speed increases, hdg should (on average) be more accurate as the distance between points is larger and subsequent errors have less impact. Hope that makes sense...

On a second point, don't know if you saw the thread about the HDS Gen2 - people have suggested using the lowrance wifi 1 module which you can (relatively cheaply) get the display onto an iPad (or iPad mini), which has a much bigger screen to look at your SS data.

Apologies if you knew all that anyway!

dannett wrote:
This is very true and a point that people need to understand - "garbage in, garbage out" is the old saying! Good mosaics have to start with good data, which means straight(ish), parallel swaths recorded in good conditions. It's unlikely that existing logs that weren't created with sidescan logging in mind will produce good results, although they can still be reviewed to find objects etc. With good source data, the process of making mosaics is very easy.

Hermes - we use a smoothed course over ground which gives good results with good data. This method breaks down when the direction of the boat doesn't match this smoothed heading. In particular, going backwards will invert port/starboard! Other sub-optimal situations would be when the vessel is being set hard by wind or tide, and the direction of travel and the heading of the boat do not perfectly align.

We will be adding support for headings taken from a GPS compass in an update to the SS module at some point. At the moment there aren't a lot of users who actually have them.

Thanks for the clarification matt. Think you have mentioned the smoothing before, so my bad!

Absolutely Matt and I used garbage in which was not suitable to produce the mosaic. As I this is a great tool to review old tracks and easily identify areas of interest.

Dan

Yes Hermes I have heard of the the antenna,and it is on my wish list. 88lb Mini Kota ipilot first.
Dan

Glad somebody beat me to it, I've just been messing around with the mosaics module for the first time and it was the first thing that sprung to mind.

I'm not sure how usual our usage is but when fishing a large mark (say half a mile) we do multiple drifts and I always tend to leave the sounder recording. The runs back to the start at 4-5 mph create brilliant mosaics but the sideways drifts at < 2 mph really mess them up. Would be perfect if we could filter those out.

Many thanks,
Paul