View attachment 5695
This shot taken yesterday. Got the shot, but it took a little time. I have learned that GPS does not like pine trees.
That looks like it could have been in my back yard, Garrett. Very similar. You're right that it takes time for those kind of shots and sometimes they don't happen. I've found a couple of things as I've pushed into those kinds of places:
1. I was inspired by
@Nate The Surveyor and
@Steve Hankins to give RTK time in canopy. When I first started working with RTK, if I couldn't get a shot in a couple or three minutes, I'd figure it was a lost cause and go to plan "B". These two convinced me that you could occupy a point for 20 or 30 minutes and get a shot in some unbelievably bad canopy. Now, with the LS we make the process infinitely more simple by chucking the bad fixes and keeping the good, so the user doesn't have to do that. At the end of that half hour, you should be able to walk away from that point knowing that you have a good, reliable position.
2. I'm a solo operator so the math works differently for me than for some organizations when I'm working in canopy and I try to figure out if I want to traverse by total station or wait for RTK to get it. If I have several points that are fairly close together and don't require a lot of brush cutting to see between then the total station makes more sense, even for a solo guy. But if the points are spread out and require traversing and require brushing, then all of that figures into my selection of RTK or TS.
3. This was a bit of a surprise to me. DPOS can bet positions in canopy that you cannot get with RTK. I've seen cases where I could not get a fully verified fix even after 20 or 30 minutes. But I could process the raw data I was collecting in DPOS and get a good position on the point. Now, DPOS does not offer the same level of redundant checks that our verified RTK offers, so if I'm going to rely on DPOS on a point under tough canopy, I feel obligated to get two sessions. This way I have a comparison to prove the results. Now occasionally I can get a few RTK epochs, but I can't get all the way through my settings for number of fixes (verification and validation), but if I have a smattering of RTK epochs that agree with each other and have a good time spread (greater than 120 seconds) and the DPOS result agrees with these RTK epochs, I consider that to be a redundant check as well. DPOS opens a whole new dimension to the positioning capability of the LS.
4. You are right, pine trees are the worst. A few pine trees scattered around may slow you down a little or not at all. A pine forest is a gamble. The LS will still proof the position properly, but whether or not you'll be able to get a position at all is questionable. Some days you can, some you cannot. So it makes it difficult to judge beforehand whether the 30 minutes it may take will be a good investment. I did a survey on a few acres that was under a very mature pine forest (kind of rare these days as so much old pine has been harvested) and I could not do much with the LS. I had a lot of points relatively close together, so I did it conventionally. One of the few jobs I've had to do that with, but it worked more efficiently this way. The photo you show under the single pine with another pine or two nearby, I'd typically figure is doable with the LS given a little time, so it's certainly not as though you can't work near pine trees, it's the pine forest that it tricky.
I work in places like the picture above it all the time. I wouldn't give a second's hesitation about the success of that shot. I staked out a 25 lot subdivision last month (something over 70 stakes to set) with the LS. Half of them were in conditions very similar to what you have pictured. Normally I'd think a solo guy would be at a disadvantage to a two man crew for a job like that. But I was able to do it all and to do it all by myself very quickly and with a lot of confidence in the results.