It will be a mute point is a couple of years since passive BMs will be obsolete. Beat the rush to clean you office and send my you LS15 now.
Do you have any literature to back up this statement? Who makes the LS15? Were you joking?
Obsolete is perhaps too strong a word, because there will remain uses for them.
But Google NATRF2022. The official definition of new elevation data will be based on GNSS and a geoid model, rather than physical monuments.
Very interesting reading concerning NATRF2022 at https://www.esri.com/about/newsroom/arcuser/moving-from-static-spatial-reference-systems-in-2022/.
The funny thing about the new datum is that around the PNW they will be very similar to NGVD29. Go figure.
I was kind of joking. As Bill says, the new vertical datum will not based on passive marks. Levels will still be needed locally to keep relative control vertically precise. The LS15 is Leica's current 1st order digital level. I'd love to replace my DNA03, their previous 1st order model, purely for the fact that the LS15 uses the same batteries and data format as my CS20.
The change to GPS based elevations scheduled next year will be a beginning.
I'm doubtful I will ever need to deal with it.
It will take some time to work through the system.
FEMA mapping which is as political as it is engineering will take many years to incorporate the new elevation basis. FEMA mapping is a big driver for changes.
I can see DOT using it for new projects after a few years to let it settle in. Yet older projects in the slowed down pipeline already designed won't change.
Anyone under a certain age will be subject to the new elevations down the road.
https://www.nrcan.gc.ca/maps-tools-publications/maps/height-reference-system-modernization/9054
Heights on the traditional benchmarks are also available in CGVD2013. These heights come from a readjustment of the entire federal first-order levelling network. However, CGVD2013 heights obtained from GNSS and geoid model CGG2013a prevail over the published elevations because NRCan cannot confirm the accuracy of the heights and stability of the benchmarks derived from the aging levelling network.
NEW:In 2022, the US National Geodetic Survey (NGS) will replace the North American Vertical Datum of 1988 (NAVD 88) with a geoid-based height reference system called the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). This future US datum has the same definition as CGVD2013 and at the time of release will enable a unified continental height system.
NRCAN's PPP system will become a lot more useful for my friends south of the border once uptake of NAPGD2022 takes place IMO.
Whether you want to is another story
I have no experience using a least squares adjustment (LSA) in any aspect of surveying. I can read about in a textbook, but I don't know how it's used in the real world. It seems to me that the key words in its use are "redundant observations." I conclude that topo traverse points elevated in a straight level run between two published benchmarks don't warrant the use of LSA because the traverse points have only been observed once. I further conclude that running at least two looped or straight level runs between two published benchmarks, in each case, through a new benchmark warrants a LSA on the new benchmark.
What I meant by that comment is that LS offers a way to honor all measurements in a redundantly measured system. It doesn't release you from the responsibility to do a proper job of measuring.
The LS15 is Leica's current 1st order digital level.
I just read about it. I wonder if Leica has solved the problem of shade on a level rod with this new level.
The shade issue was a big problem with the old NA2002 levels but I have not had much troubles with the DNA03. I'm sure the LS series is an improvement. These instruments are based on visible light cameras so you have to figure that lighting conditions are going to effect them some.
When shade is an issue, are there any alternatives to setting up on the other side of the road or rotating the level rod to gather more sunlight? If you do the later, at what point (30 degrees, 40 degrees, etc.) of rotation is the accuracy of the reading affected? I've never tested that.
As John said, its not a big problem with the newer models. It has to be really dark to be one. But if you were levelling underground or something you could bring along a really strong flashlight and illuminate the rod.
Once you've done levelling with digital you won't want to do it any other way. The only reasons to stick with optical only levels are 1) expense, and 2) batteries. Item 2 is an extension of 1, and 1 takes care of itself by inreasing efficiency if you are doing much levelling at all.
Vegetation is also a digital-killer, as the level needs a clear view of a relatively large patch of rod in order to obtain a reading. So if you're trying to look through leaves or between branches, it doesn't work well, if at all.
That was true with the NA2002. Not so much with the DNA03. These are the units I have the most experience with.
