"Fixed" should not necessarily be considered synonymous with "good" or "correct" especially in bad locations. More time would improve the result. In an area like that I would try 20 minutes.
Oh I know. When I went in there I knew it wouldn't get good results, I certainly didn't expect it and I'm not concerned it didn't. My post is driven more by a question of minimum duration of time rather than why didn't this work out. Could more time have made a better result?
Also the PPK come's back as fixed and I'm interested in knowing if they always come back fixed. Have you ever gotten a failed PPK solution?
You may have to set there for a long time, how long, I am not real sure there are any set rules for how long to occupy when in canopy, just experience. My preference would be to check it again later too. A PPK solution can come back as a float solution. Fix is statistical, not neccesarily meaning it is a correct solution.
The LS will get correct and very accurate data in coverage such as this - at times. Other times it won't and will require as Adam and others have said at least 10 minutes of PPK. I learned the hard way also testing like you've done and had several PPK solutions come back "fixed" but not be correct using the five minute minimum, so I've upped my "line in the sand" as Adam called it to 15 minutes in heavy canopy.Oh I know. When I went in there I knew it wouldn't get good results, I certainly didn't expect it and I'm not concerned it didn't. My post is driven more by a question of minimum duration of time rather than why didn't this work out. Could more time have made a better result?
Also the PPK come's back as fixed and I'm interested in knowing if they always come back fixed. Have you ever gotten a failed PPK solution?
I learned the hard way also testing like you've done and had several PPK solutions come back "fixed" but not be correct using the five minute minimum, so I've upped my "line in the sand" as Adam called it to 15 minutes in heavy canopy.
One thing I've started doing quite a bit with this LS, I think it might've been Jim Campi who first mentioned it, is to rotate the LS in a different direction to try a little different alignment.
However, if I do this, as long as the unit is on a bi-pod, and stays plumb, would/could it affect my PPK raw data that I'm collecting by moving it just a titch?
Darren, very good info!
I believe that if I took that same observation under that beech in mid December I'd not only gotten good PPK values I'd probably gotten good RTK values too.
The time duration is the learning curve on the LS for me.
Hope no one takes my post as a knock against the LS/T1M, the fact that it got within 2 feet of the real value under that tree is still IMPRESSIVE! I believe the Javad systems are the best on the market, wouldn't have bought one otherwise!
View attachment 5477 View attachment 5478 View attachment 5479 Well gentlemen I think the one I got this morning takes the cake. One of the most amazing things yet I've seen this LS do. Was 10 am in the morning but was almost dark as night the canopy was so thick. Was about 3' away from a 30" oak with a 10" beech right next to it.
When I got to this point I was sure I'd have to stay and get at least 2 separate 15 minutes dpos sessions.
I had the first validated RTK in SIX minutes! Stored that shot and started another and intentionally let it run for 15 minutes to get a dpos, which I base processed after getting back to the office within 0.017!! from the RTK shot!!
The most amazing of it all was a good portion of the phase two collections were with 6 full engines.
The main reason it's so frustrating sometimes is like I said, this LS has completely spoiled me! It gets points like this in six minutes and regularly, reliably, goes where like they say in Star Trek "where no GPS surveyor has gone before" so when I have days like last week - lots of what I'd call marginal canopy - and I have to do 15 minutes after 15 minutes to process dpos, I think something is wrong.It is hard to say sometimes. Most of the time I am amazed with where I can go reliably. Sometimes I'm disappointed. I see that picture, Darren, and it looks like any given Tuesday for me. Generally, if I have to wait for thirty minutes to get that shot (like you said, two DPOS solutions) it's worth the time compared to conventional traverse for one man. So when I can get them in 5 minutes, it's a bonus. I agree that wet leaves make it much harder to get a verified position in canopy like that, but I haven't really noticed any problems on cloudy days vs. uncloudy days. I did have a job this week that was all total station. Too many pine trees to use GPS. I tried, but it just wasn't going to happen. So far I get about 80% of my work done with the Triumph-LS (boundary surveying mostly), and I find myself in places like you show in your picture frequently.
Good for you getting that kind of redundancy on those points. Javad gives you enough on the front end to know you have a good point, but the surveyor in me likes to see redundancy.