Bottom composition is recalculated for a point (and also the surrounding points, as BC is averaged over a number of pings) when it is edited, to take the new depth into consideration. They should certainly still contain bottom composition information after being edited, so if you can show an example of this not happening that would be useful - it would be a bug.

thanks,
Matt

Hi Matt,

I've attached the screen shots for the unedited versus edited sonar data. You'll notice that there are many more grey sediment points on the edited file. When I map this edited file for BC....it gives me a map with many sections missing. Let me know if you need something else to look into it. Thanks!



Unedited



Edited

And here is the BC map it generates....you'll notice that those grey points seem to correspond to the gaps in data.




Unedited



Edited

Thanks Pondguy - we will look into it and let you know!

Any updates with this?

Not yet. I will let you know when we have looked into the issue.

thanks,
Matt

Hi Pondguy,
We are looking at this now, and cannot reproduce the issue.
One possibility that springs to mind is that this is the E2 layer, and when the track-points are edited they become so deep that the second echo return (E2) is no longer available. E.g. if your sonar limit is 50 feet, and the TP was originally at 10 feet, then you'd get a second echo return. If this TP was then edited to something over 20 feet, then the E2 layer would not be available for that point (E2 requires at least double the depth + the full thickness of the bottom return).

Could this be a possibility? Are you seeing data loss for layers other than E2?
When you edit the TP in the SV (with hardness selected in the track), does the TP become gray in the SV or does it change to a valid hardness colour?

thanks,
Matt

Hi

I am new to RM and am trying to figure out how to get a Bottom Composition map made. I can import my data I get the info on bottom type but cannot figure out how to generate a bottom composition map.

please help

Hi salad??

Guess you have the bottom composition add on for reefmaster? It should show a symbol on the left hand side with layers of dots - as shown in this forum topic display and from pond guy and e.g. below (don't think it shows it in the global view - you have to already have created a depth contour or 3d map first) .

If you do have the RM bottom composition add on, have you managed to create a contour map with depths? (apologies if I'm teaching you to suck eggs, but it's difficult to see what stage you are at from your question). If not, the help files within the rm software are excellent - especially if you follow some of the tutorials from Matt on how to make a map from start to finish.

If you have managed to create a depth contour or 3d map, it should then just be a case of clicking on the 'bottom type' symbol (icon with layers of dots), to display the bottom hardness (you can then fiddle with the edit settings to get it how you want it to look).

It took me a while to figure out how to get a good map up, but it's worth persevering - once you've done it once, it becomes relatively easy And you can produce some stunning 3d maps with hardness / composition overlaid (in the e.g. below, i haven't added satellite imagery or anything, but it is possible if you wanted).

Thanks Hermes - and a nice looking map!

Salad - Hermes has covered it, but really it should be as simple as clicking the "Show Bottom Composition" button in the toolbar of the map project. This button will only be enabled if the project contains tracks (at least one) that have BC information. If you can see BC information in the individual track edit windows, then this should be enabled in the project view. Click the button to calculate and show the BC layer - that's all there is to it.

For more on bottom composition, take a look at this manual page.
For more on map making in general, take a look at the make a map tutorial.

Matt

Hi Matt,

It doesn't have anything to do with the Sonar depth. This is a shallow pond (only 10' deep) and my range was down to 75'. Below you can see the screen shots that clearly show the greyed out points and the second return for both the PeakSV and EV2 layers. Strangly, when I re-edit the points to a deeper depth and bring them back up to the correct depth, they turn a color but then the color disappears again. This is happening to all my files....mainly in shallow water. Do you want to see this particular file?



PeakSV



EV2

Hi Pondguy,
Yes - it would be helpful to take a look at that file to see if we can understand what is going on.
If you could share it via Google Drive (or similar) and send a link through to This email address is being protected from spambots. You need JavaScript enabled to view it. that would be great. Note that if this is HB track we will need the .DAT file and the contents of the sub-folder with the same name, that contains the .SON files.

thanks,
Matt