Static/PPK in the woods

#1
Once I put three receivers (no Triumph-4X similarity) in an equilateral triangle configuration (imagine 3xT2 bonded together with some light mounting support, no more than 30 cm in diameter).

Then static/PPK them with a base or CORS in open, medium and dense canopy, but with three different post-processing software.

Although the results cannot be published, there are some things that I can take the courage to say:
-if you have the triangle condition fulfilled on the screen between those 3xT2 receivers (with some small imprecision), then the surveyed point is 100% reliable;

-for some critical points I spent in the field more than a half an hour of 1s continuous surveying in dense canopy to obtain all vector fixed (office post-processing).
 
#6
Just to mention that OpenCV (Open Source Computer Vision) is a library of programming functions, mainly seeking to automate tasks that the human visual system can do, like interpreting the surrounding environment. It was developed by Russian experts and Intel many years ago. Now the rezults are beyound expectations.


In bad canopy any commercial receiver does not produce satisfactory data in short observation sessions. But I learned a two lessons: even the worst forests have small windows above; it's not bad to be crazy sometimes.

So, I must admit that it would be very useful to have a drone whose main task is to raise vertical over the canopy through those "small windows" at 30-50m height above us(picture1), get a stable position on the same "vertex" with my monument(picture2), measure and go down.

Maybe we can find a balance between accuracy/precision/time spent with all these useful devices. Part of my life was calculating static/PPK in the woods.
 

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Nate The Surveyor

Well-Known Member
#7
I have found that ppk in the woods... Can be wrong, especially with short observations.
If it's got woods, it needs 2 to 4 observations, of 10 to 15 mins long.
Keep in mind, I'm pushing my equipment... And its a good idea to NOT trust a single short observation, in woods. I did 3 - 7 minute observations earlier this week. They were all wrong. Later, I let it set for 20 mins, and it got it with rtk, and ppk was some 0.16' different. This was fine for me, because I had other things to do, while it worked.
I had a total station shot, and it was a building corner. The gps was set at a 5' offset.
It's not critical, (0.2' is close enough) but, it illustrates that IF, it cannot get rtk, then it probably does not have good ppk. (I had good radio signal).
 
#8
Thank you very much Nate, for sharing your experience. Now just imagine a 500-800m versant near you and a pine forest. Instantly we forget any of the launched or not yet launched satellite constellation. As you mentioned, total station is our next option.

As a test, we will equip our total station with a diagonal eyepiece for comfortable obersevations of steep sights. Then with the scope toward zenith (verical angle = 0 grad), will turn on laser pointer and try to catch the drone above (I think the drone can do this automatically if it has a laser receiver).

Even Triumph LS could have something attachable - vertical(zenith) laser plummet as a "ground support" for a pocket size, yet powerful tri/quad/multicopter which should be a standard accessory for J-Pack.
 

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#9
Because drones are the carriers of high-precision GNSS signals, many surveying projects (and not only) will need to transfer the geolocation accuracy from air to the ground (D2G).

This is a clear concept with a special prize around here.
https://www.gsa.europa.eu/newsroom/news/drones2gnss-takes-year’s-gsa-special-prize

I'm so curious to see a 15-20 min raw data file from Triumph-F1 while it is at 30-50m in the air at a fixed(stable point). Perhaps a different approach for GNSS post-processing.
 

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#10
Tiny mirrors (which "shines" from only 40 miles away from San Jose headquarters) could transform the workflow as we know it in the woods.



MEMS mirrors enable simple, compact, and low-cost implementation of laser tracking as well as drastically lower power consumption.


From now on, at every static session in the woods I will think about the aerial support. :rolleyes:
 
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#11
This is what we call light woods in the plains.
Light woods.png


My old receiver will struggle, but a 2016 multi-constellations machine will get a repeatable solid fix (static and RTK base-rover) in this kind of environment.

Controller1.png


This was a test without any GNSS planning, but I intend to maximize the satellite number using this service.

planning1.png


Next, I'll have to find out if a third or even fourth satellite constellation will really count at this moment. A friend will help me again with the new GNSS machine (and old controller). Another thought is not to mix all constellations at once, but to compare a classic solution (GPS-GLONASS only) vs a modern one (Galileo-Beidou only).
 
#12
Cities like Chicago are known as the real challenges environment for any GNSS receiver. Just try a simple static or staking job on the streets in the city center. No need to compete with anyone. Only finish the job. If succeeded, must print on the receiver: "Chicago test passed".

Chicago.png



But the real nightmare for a GNSS receiver could be inside "giants" like this. For inspection purposes.

Industrial tower1.png


In this case, intense photogrammetry techniques, combined with GPS/GLONASS/Galileo/Beidou high-precision positioning, will really do the job.
 
#17
Now looking from inside that kind of tower..

Industrial tower2.png


I will expect a fair answer from LS users: do you give to LS receiver any chance to store and then successfully post-process a static session or get a RTK fixed position down inside this tower? Just asking, thank you very much.
 
#18
Set your tripod up, with the points of the feet, about 1' apart. Do the best you can. It's still an unstable setup. Small foot movement, equates to large tripod head movement.

Think of a distance distance intersection, from 2 points that are 5' apart, and your distance measurement is around 100'.

It's simply "Bad strength of figure".

It MIGHT get it, WITH HIGH rms values. So, What's the value of that? A 12 or so hr observation, could yield data, but it'd be weak.

Better efficiency to get a looooon pole, or offset it.

:)

N
 

Matt Johnson

Well-Known Member
5PLS
#19
I will expect a fair answer from LS users: do you give to LS receiver any chance to store and then successfully post-process a static session or get a RTK fixed position down inside this tower?
No, you would never get enough unobstructed satellites directly overhead to calculate a position and even if you did, the PDOP would be very poor. The receiver elevation mask looks like 85 degrees or so in there.
 
#20
I'm somehow nostalgic looking at my receiver trying to use a piece from the sky;

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For the moment, tandem like this are in trends:


I will add that the surveying pole represents itself a concept in which different sensors provide digital data from below the ground (ex: J-tip), details from the ground surface (GNSS receivers, MEMS devices) and from aerial perspective (drone). It seems that the old, classic rod have some hidden abilities with receivers like Triumph LS..