Hi

I got a question: I am mapping a couple of river deltas for school with the idea to monitor (with a Humminbird) their development over a certain lapse of time. Now to my problem. Everything went well during the measurement and I could import .gpx files into ReefMaster except the fact that all Trackpoints between 0 und 1 meter depth seem to lead to miscalculation. As soon as I exclude those points everything is back to normal and works well, but I would be glad if there was a way to include them because I need exactly those shallow depths for further work in Autocad.

How can I make ReefMaster „accept“ or include those Trackpoints?

Any advice is welcome.

Roman

Hi Roman,
Can you describe the "miscalculation" a little more? Shallow depths should be treated just like any other depth once they are included in a map project. It is possible, however, that you have a number of zero depths that are being excluded automatically during import. If this is the case, you will need to reimport your files and uncheck the "exclude zero depths" option in the import window during the import. This option can be useful to remove bad depth points from tracks, which are very often zero depth. Depths that are non-zero, even by a very small amount, should always be imported.

Matt

Yes sure. Sorry. It's probably easier if i post a picture of what the "error" looks like. Well i unchecked the "exclude zero depths" option when importing and it still showed me the same things.
What else could there be?

Is it possible that these are in fact zero depths, but they have an offset applied at source and are being exported as a small non-zero depth ?

T

Interesting - it's not obvious to me what could be happening there, other than the possibility that those are just bad data points. What is the depth of the rest of the project, and what depths are these points?
Send the workspace (.rmdb file) through to This email address is being protected from spambots. You need JavaScript enabled to view it. if you like and I will take a look.

Edit: if you could send through the original GPX file as well, that would be great.

I tried working with adjusting the offset a little bit. But nothing really changed, or when just a little bit. The only thing that helps was filtering the depths. But as written it's important to me to also have depths that lay between 0 and 1 meter. I sent you the asked data. Hope you can manage to see what's wrong.

Hi Roman,
It looks to me like your cone angle is wrong - you had it set at 86 degrees, which is extremely large. RM will look at the cone angle when gridding the depth data, and the rough basis of the algorithm is that it considers that the region around a given data point (described by the extent of the sonar footprint) cannot be shallower than the recorded point. You might get some odd effects when this value is wrong, particularly if it is very large (it's not really a problem if the cone angle is specified as too small).

Below is your map, with a cone-angle of 20 degrees specified for your track:

Definitely makes sense! Thank you for helping me out!