When I log the bottom I have a track point on 1,08 m but it is not included in the map later on. On the map it shows about 3 meters.

The thing is that it is about 3 meters, but there is a small rock where the depth is only 1,08 meter. Whys is this not shown on the map? Is it because of the interpolation?

I have reduced the interpolation to minimum, 25 meters, is there anywhere it can be removed completely.





Basically I think my question is "How can I include small rocks on my maps?"

Anyone?

From the image of your track-points it looks as if you have some deeper points very close, and likely within the range of your specified cone angle (default 20 degrees). If two points fall within the coverage of the cone angle, then the deeper point will be preferred. You can eliminate this filtering effect by setting your cone-angle to a very small value - try 1 degree - and also reducing smoothing for the project to a minimum (you can try 1 again). If that still doesn't work, then you will need to edit your track-point data to remove the deeper points that overlap/are within 1 metre of your shallower points.

Thank's for your reply. It worked partly... :)

If i do as above, I will be able to reduce the depth, closer to the real, but still a difference of 0,3 m approx. I have no tide, and I have also checked the keel offset.

I also thought that if I took the original file and removed all track points deeper than the specific rock, I should be able to make a new file, and then combine this file with the original in order to tell the system that it is a rock there, but the system seems to interpolate between the files, is that so?

Where I live we have these stand alone rocks so to speak everywhere, do you have any suggestion of how to show them in the software. Is it possible to add track points manually?

The interpolation method we use - TIN with some smoothing - does not guarantee that recorded depths are always represented in the finished map. This is particularly noticeable in cases like yours, where there is a very small feature. Since there is always some smoothing applied (even with smoothing set to 1), some of the feature is eroded. If you want this feature to appear on your map, you may need to consider using waypoints or drawing in the feature by hand in a User Map. I should also probably take this opportunity to reiterate the point that ReefMaster generated maps should never be used for navigation!.

This may not suit your purpose but I make use of custom paths to add extra detail to my RM maps. I use a different colour / line thickness for different items and have a created a separate map in RM. In my case the objects of interest are traced from sidescan mosaic imported as images. Some care is needed as there will be minor variations in location due to normal GPS variations, etc. The resultant shapefiles are then processed with IMC and included on the SD card with the RM contour maps. This is a fair bit of work but worth it in my opinion. I have also been able to reduce the number of waypoints that I have in my sonar/gps.

The example below shows 2 rocks that are about 10 metres apart.