Locating resource areas (top bank of river etc)

[Patrick Garner]

Here in New England, in addition to boundaries, we also locate a lot of environmental features such as wetland edges, top of bank for rivers/creeks, pond edges etc. These features may be under light to medium canopy.

Has anyone got suggested routines for doing this fast with the LS? Accuracy can be between 0.5 and 1.00 feet. Any suggestions appreciated!

 

[Matt Johnson]

Here in New England, in addition to boundaries, we also locate a lot of environmental features such as wetland edges, top of bank for rivers/creeks, pond edges etc. These features may be under light to medium canopy.

Has anyone got suggested routines for doing this fast with the LS? Accuracy can be between 0.5 and 1.00 feet. Any suggestions appreciated!

This isn't possible with RTK. The fixed ambiguity solution is either right or wrong, there is no middle ground. To guarantee the fixed solution is good, we find that you need to have an initial initiation and a new initiation after resetting the engines that are separated by some duration of time. In light canopy 2 minutes should be sufficient and 3 minutes is recommended for medium to heavy canopy.

 

[Patrick Garner]

Thanks, Matt. In other words, it's either highly precise or not? No 30 second time, for instance, that yields lesser accuracy?

 

[Matt Johnson]

Thanks, Matt. In other words, it's either highly precise or not?

Correct

No 30 second time, for instance, that yields lesser accuracy?

Multipath causes the RTK solution to drift so longer observations will help smooth the solution and yield better accuracy in areas of multipath.

 

[Patrick Garner]

Michael and I were speaking earlier today and he reminded me that the LS comes configured for Boundary, Quick Topo, etc.

How would you recommend configuring the LS for the sort of location work I described in the 1st post?

 

[John Evers]

Patrick,

What I do is also rely upon my previous shot to help confirm the location of a new shot. An easy way to do this is by keeping an eye on the distance to last white box button.

When I do topo in the woods, I look ahead to my next shot and estimate the elevation difference. I then pace the distance. When performing the shot, I can spot a bad fix 90% of the time by paying attention to this. I use relatively relaxed settings of "Confidence Resets of 7", two engine required, 45 epochs at 5hz, No validation.

As an example of locating the meanders of a creek, the elevation difference should be consistent and predictable.

One other strategy I use to locate wetlands is to stop the corrections from the base via any of several methods. I also have SBAS enabled, which is found under General Setup/ Advanced/GNSS. You will see this displayed as CDF instead of FLT or FIX.
When doing this I also record static, and have a shot duration of 90 seconds. I then use our DPOS capability and post process the shots. I find that the vast majority will provide a fixed solution. The worst CDF solution, is almost always better than a float, or a bad fix. Using this method, I also rely on the graphical ability to spot a bad shot when the data is plotted.

 

[Patrick Garner]

John, thanks. You've answered exactly what I was asking. Will try this out this weekend. I'm trying to cram a month's worth of learning into a couple weeks. While continuing to run my usual business.

 

[Adam]

I can add a little to what John said. Distance to last is always on because it's quality control at a glance. For moderately wooded canopy shots that I want within a foot I will use an action profile that has a confidence of 5 and a minimum phase one duration of 30 seconds, zero consistency and no verification. The minimum total duration is set at 30 seconds as well. So basically you are using the verification phase only and not refining the measurement. I bump the confidence gaurd up to .5 horizontal and .5 vertical, this allows the somewhat sloppy epochs thru that we try to avoid on precise shots. Like Matt said which all of the 5pls team agrees on, unless you have enough time from first epoch to last you don't know if the fix is correct. I have also seen a bad fix last over two minutes. Ive never seen one last over three.

 

[Steve Hankins]

I can add a little to what John said. Distance to last is always on because it's quality control at a glance. For moderately wooded canopy shots that I want within a foot I will use an action profile that has a confidence of 5 and a minimum phase one duration of 30 seconds, zero consistency and no verification. The minimum total duration is set at 30 seconds as well. So basically you are using the verification phase only and not refining the measurement. I bump the confidence gaurd up to .5 horizontal and .5 vertical, this allows the somewhat sloppy epochs thru that we try to avoid on precise shots. Like Matt said which all of the 5pls team agrees on, unless you have enough time from first epoch to last you don't know if the fix is correct. I have also seen a bad fix last over two minutes. Ive never seen one last over three.

Adam, how many engines with this profile?

 

[Adam]

Adam, how many engines with this profile?

I have it set to 2 engine. The minimum engine requirement only pertains to phase 2 and validation. With this set up I am using neither of those so that requirement doesn't really play in since I am only using the phase 1 verification. Be cautious and pay attention to the DTL.

 

[John Evers]

The minimum engine requirement only pertains to phase 1 and validation.

Adam meant to say: The minimum engine requirement only pertains to Phase 2 and Validation.

 

[Adam]

Thanks John

 

[Patrick Garner]

A perhaps dumb question but wouldn't the Quick Topo Action basically address my original "how-to" question for resource locations? Or does it require too many engines (I think the Quick Topo option is 5-eng)?

 

[Adam]

I only use the quick topo profile for open skies.

 

[Patrick Garner]

Makes sense.

It appears there's no way to create a custom Action that would incorporate what you and John have suggested. Looks like the Actions are built into the software, although something new could be added in time--?

 

[John Evers]

Actions are completely user definable. If you have not created any, then the ones you are seeing are simply "examples".

On the Setup screen, we have three different types of configurations, all user definable.
The top row of setup buttons pertains to your General Setup, which is primarily concerned with "how your system communicates".

The middle row in Setup, which is named the "Action Setup" pertains to How the measurements are performed, and what white box buttons are assigned in the Collect and Stake screens.

The bottom row of buttons pertains to codes and tags.

Regarding the Action Setup, my preferred method to create a new profile is use the Copy As button, and give the profile a new name. Then Edit any settings you want, and you have your own custom profile.

 

[John Evers]

but wouldn't the Quick Topo Action basically address my original "how-to" question for resource locations?

Another valid strategy for your question, would be a Confidence (resets) value of 5, with total epochs at 5. This would give you a rather high confidence shot considering your application, and would occur rather quickly. I would estimate that in difficult conditions, this will yield one bad shot out of 50 shots. Additional confidence can be obtained with a reset RTK, and satisfaction with the Dist to Last values before you leave the spot.

 

[Darren Clemons]

I can add a little to what John said. Distance to last is always on because it's quality control at a glance. For moderately wooded canopy shots that I want within a foot I will use an action profile that has a confidence of 5 and a minimum phase one duration of 30 seconds, zero consistency and no verification. The minimum total duration is set at 30 seconds as well. So basically you are using the verification phase only and not refining the measurement. I bump the confidence gaurd up to .5 horizontal and .5 vertical, this allows the somewhat sloppy epochs thru that we try to avoid on precise shots. Like Matt said which all of the 5pls team agrees on, unless you have enough time from first epoch to last you don't know if the fix is correct. I have also seen a bad fix last over two minutes. Ive never seen one last over three.

Adam and John, when using profiles such as this, would you recommend, as John states above, doing a reset RTK and immediately hitting start again, then use distance to last to hopefully gain additional confidence? With these somewhat "soft" settings hopefully it would give me another couple of clicks quickly.

Again, dist to last is the greatest button there is here. As long as you are certain on you're first shot, then keep up with the approx. horizontal and especially vertical and you can most times tell very quickly what's good and what's not. We also do exactly as John describes with "estimating" the next shot. I did a massively deep dark creek meander last week this way. I actually spent more time than I probably had to by having my settings a bit too high for that type of shot and was glad to see Pat start this thread to read what others were doing on these areas.

 

[Patrick Garner]

John: epiphany. That did it. I get it. Just created a new action from your and Adam's suggestions. Very cool. Kudos & thanks.

Darren, glad you mentioned the RTK reset. What would be the purpose of doing so? Sounds like a good way to slow down collection. Obviously, I'm missing something!

 

[Darren Clemons]

John: epiphany. That did it. I get it. Just created a new action from your and Adam's suggestions. Very cool. Kudos & thanks.

Darren, glad you mentioned the RTK reset. What would be the purpose of doing so? Sounds like a good way to slow down collection. Obviously, I'm missing something!

Re setting the RTK and/or re setting the engines kind of "clears" out the data and lets the process start over. It's very useful and becomes almost necessary when traveling through very rough terrain. When we are walking through extremely rough canopy areas, the first thing I do when I get on the next point I want to shoot is re set the engines. The LS is continually "tracking" satellites even when we're walking and it seems to help to clear everything out when you get to a new point and before beginning collection. I even do it during the three phases of RTK if things seems to "bog" down. Many times, on very heavy canopied shots, the third phase validation will be very hard to complete. I will sometimes reset engines during this and that will help that process finish.