I do a lot of ground control for USGS 3DEP program. There are several types of points, one of which is VVA-Forested, which means getting a LiDAR checkpoint in the woods. The quantity of VVA-F depends on the dominant ground cover. I did one recently with 450 points (11,000+ sq mi) in the upper midwest that had only 4 woods points, and another one this month in the mid atlantic area that had 60 woods points out of a total of 180 points (2400 sq mi). That area was forested mountains?ÿ
For years we would use GNSS to set two points in the open, and then use a total station to locate the point in the woods. Then I upgraded my R10 receivers to R10-2 (only two of the four were capable of being upgraded), which meant ProPoint. After some testing, I determined that setting a base nearby we could get good results in full foliage woods with the R10-2 if we used all four constellations (GPS, Glonass, Galileo, and Beidou). And leaf off even easier.?ÿ?ÿ
The VRS (Keynet) in the area I live in (NE US) apparently only uses GPS and Glonass. This means we have to set a base nearby (typically on the roof of the vehicle) and do RTK over radio or cell. However, I use the Trimble VRSNow system sometimes and, at least in the areas I was in, it uses the 4 constellations, and I could usually get good VRS in the woods, although the work was done leaf-off.?ÿ
On the other hand, there are areas in the east where it still requires the GNSS pair/total station method in mid summer due to really thick canopy.?ÿ?ÿ
I am wondering how many of the VRS systems in the US have upgraded their receivers and network to use 3 or 4 constellations??ÿ
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Not Indiana. ?ÿLast I checked, they don??t know when. ?ÿI really wish they (we) would, please.
I think NC now has all four.
Florida DOT has 4, and better post process than OPUS.
Missouri's (MODOT) statewide network doesn't all have Galileo yet, according to the FAQ section on their site, but will upgrade as funds allow.
Did you do any of that work up in Michigan? In 2018 I was up in Charlevoix county using the MDOT VRS?ÿ with an R8-3 and got pretty good results with GPS and Glonass.?ÿ
In Las Cruces we weren't using anything except (GPS and Glonass)what Dona Ana county provided in the VRS supporting the EBID and that was always suspect to outages and delays for updates depending on funding and covid etc.
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@brad-ott I realize of course it is a financial decision, getting new receivers costs $$$. The decisions being made by a government entity (DOT, etc) are surely different than a private for-profit entity.?ÿ
I have heard that there may be a nationwide player coming along soon, so that may change everything. The autonomous vehicle market will be many times larger than the survey and ag market, IMO. I just hope they don't forget about us.?ÿ
I can say that it definitely makes a difference in init times and accuracy. And of course in the woods or other compromised locations.?ÿ
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@jitterboogie Never did any USGS work in Michigan. But that VRS has been around for quite a while.?ÿ
I think NC now has all four.
Agreed. Update notice from admin in June 2020:
As of today, June 1, 2020, the VRS_CMRx and VRS_RTCM32 mountpoints have been configured to include the Galileo and BeiDou satellite data into the correction solution to NC RTN users. CMRx and RTCM 3.2 are the only versions of the output formats the NC RTN has available for the mountpoints that support the Galileo and BeiDou satellite data. The other mountpoints (VRS_CMRp, VRS_RTCM23, VRS_RTCM3) will still include only the GPS and GLONASS satellite data in the solution. Although the VRS_CMRx and VRS_RTCM32 mountpoints are now configured to include the Galileo and BeiDou satellite data, users may not receive any BeiDou satellite correction data because the NC RTN application can??t process the data from the latest BeiDou satellites (BeiDou-3) yet.
I haven't done any heavily canopied topo work since that time (mostly blue sky areas) so, I'm unsure what vertical improvements have been realized.
Side thought/ seeking concurrence- It is the L5 signal that improves canopy shots, correct?
Anyone in NC seeing vast improvements? Do we really know 😉
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EDIT: I want to add, the NC RTN kicks arse. Thanks to all those that maintain it and keep it available to our community. ????ÿ
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Our local net has been using all 4 for maybe 3 years although Beidou has only been useful for the last year.?ÿ The biggest bump for us was Galileo a few years ago.?ÿ Getting 10/10 Beidou right now.
@ekillo do we? see I thought the same too but then a certain brand salesman the other day told me that NCGS's VRS system was only GLONASS & GPS still? If so that would be a huge help for me in making some equipment decisions moving forward in 2022
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** edit - nevermind I saw backchain's response
Oregon's ORGN has three of the four on many of their CORS.
Ohio's VRS does
A portion of NYSNET has four constellations.?ÿ
For deep woods projects I set control points or occupy monuments with Static GNSS network using as many as 12 recievers. Oftentimes I use atleast four. Much more reliable than RTK or VRS. It looks like very few surveyors post process their own static observations these days. RTK/VRS or OPUS for most.
Here in Maine MDOT has just GPS and Glonass at the moment. heard upgrades are coming.?ÿ
