Topic: need guidance on AutoChart recording

[newkid4si]

Suppose I have an area of a lake that I want to map with AutoChart and I think it will take an hour and a half to record using the proper speed and grid pattern.  I also want to use the recording to play in HumViewer.  HumViewer works best with recordings limited to 20 minutes.  I don't know if AutoChart works best with several small or one large recording.  I assume that you can use the  recorded information for both.  Anyone have experience doing this?

A second question.  After creating the original map, you see an area that you would like in greater detail.  You return to that area an run a tighter and slower grid pattern.  When you add this information to the original map, does it add to that map or do you have to make a whole new map?

            Mike

[Bob B]

I haven't started using Autochart yet, but my understanding is that a series of smaller recordings is preferred.  20 minutes sounds like a good starting point. 
When scanning, it is possible to get some bad data due to water turbulence, etc.  When I watched the Lake Images training, he mentioned that it is easier to correct those type of problems with a smaller file.

I would strongly recommend the Lake Images tutorial if you haven't got it ..... it will save a lot of startup time.

[newkid4si]

Thanks Bob

       Mike

[rnvinc]

Note ...:

Humviewer works normal with larger files ...

It simply takes longer for the GPS data file to load into Humviewer ...

Rickie

[newkid4si]

I remember some of my previous recordings being 46-47 minutes long and they worked in HumViewer, although as Rickie said , it takes a while to load.

In CamoHunter excellent tutorials, he had 5 files for the first part of his map.  I can't determine how long they are or how much area was covered.

It looks like trial and error time.  Apparently, if the map that is created doesn't look good enough, you can delete it and start over.

Bob--- I think I'll order the Lake Images program. They are a board sponsor and I have seen good feedback on them.

         Mike

[Bob B]

Keep us informed of your progress.  I planned to be using Autochart PC right now, but haven't been fishing the little lake I had in mind.

[newkid4si]

Bob

     It will probably be April before I get on the water.  I'll share what I find out.

         Mike

[rnvinc]

I remember some of my previous recordings being 46-47 minutes long and they worked in HumViewer, although as Rickie said , it takes a while to load.

In CamoHunter excellent tutorials, he had 5 files for the first part of his map.  I can't determine how long they are or how much area was covered.

It looks like trial and error time.  Apparently, if the map that is created doesn't look good enough, you can delete it and start over.

Bob--- I think I'll order the Lake Images program. They are a board sponsor and I have seen good feedback on them.

         Mike

The consensus is not to delete and start over ... but to remap and let the new AutoChart Live creation adjust and self-correct itself ...

This (supposedly) gives a more accurate end-creation map than "one pass-and done" ...

Even mapping companies grid from several passes to account for the Sonar phenomenum of "target masking" creating the "Dead Zone" of a Sonar beam cone angle ...

http://www.vexilar.com/blog/2014/08/28/choosing-a-transducer-beam-angle

Rickie

[newkid4si]

That's information I can use.  It's easy to visualize making a map and seeing an area that you wish had more detail. Thanks Rickie.

           Mike

[October1]

I didn't realize that's how it worked. I thought it showed the returns from all depths the beam hit. Good to know.

[rnvinc]

I didn't realize that's how it worked. I thought it showed the returns from all depths the beam hit. Good to know.

Target Masking is a Sonar phemonenum not well discussed in 2d sonar ...but a very real issue ...

Any target farther away from the xducer than what the unit "thinks" (and paints) as bottom in the sonar scroll window is blended into the colors of the bottom detail being painted along the bottom of the displayed 2d image ...
 
This is exactly why mapping companies grid map survey ...because target masking occurs at sharp changes in bottom depth ...and mapping from a different direction helps gives more accurate depth data to re-adjust the previous data points affected by target masking ...
 
Rickie

[October1]

Target Masking is a Sonar phemonenum not well discussed in 2d sonar ...but a very real issue ...

Any target farther away from the xducer than what the unit "thinks" (and paints) as bottom in the sonar scroll window is blended into the colors of the bottom detail being painted along the bottom of the displayed 2d image ...
 
This is exactly why mapping companies grid map survey ...because target masking occurs at sharp changes in bottom depth ...and mapping from a different direction helps gives more accurate depth data to re-adjust the previous data points affected by target masking ...
 
Rickie

After having a moment to think about it, it seems DI & SI wouldn't have much of a problem with target masking because of the thin beam.

[fshndude]

Just this past Saturday I went out and mapped a creek. It was a 3 1/2 hour long recording. Auto chart did it beautiful, humviewer worked great. BUT it sure took a long time to load in humviewer. I am just breaking the surface with my auto chart. I do recommend the Lake Images DVD. There is so much information, plus so much you can do with auto chart. So I guess to answer your questions it don't matter how short or long your recordings are.

[jimham82]

There is a certain amount of risk involved in long recordings. The unit may freeze up and need to be restarted causing loss of data. Also, the SD card could have a problem. I have encountered both of these conditions over the years

[newkid4si]

A Navionics rep suggested keeping the recording length to 30 minutes for two reasons.   1- ease of working with data.  2- if you get bad data, you don't need to do the entire area again, only the bad section.  Makes sense.

        Mike

[Bob B]

After having a moment to think about it, it seems DI & SI wouldn't have much of a problem with target masking because of the thin beam.

I would think that if you are traveling parallel to a drop you would have the same problem with SI and DI that you would with 2D.  A constant shallow return from the top of the drop would be perceived by the unit as the bottom.....Not sure how deeper returns would be processed.