The funny thing about the new datum is that around the PNW they will be very similar to NGVD29.?ÿ Go figure.
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.?ÿ 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.?ÿ?ÿ
Once you've done levelling with digital you won't want to do it any other way.?ÿ The only reasons to stick with optical only levels are 1) expense, and 2) batteries.?ÿ Item 2 is an extension of 1, and 1 takes care of itself by inreasing efficiency if you are doing much levelling at all.?ÿ?ÿ
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.?ÿ So if you're trying to look through leaves or between branches, it doesn't work well, if at all.
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That was true with the NA2002. Not so much with the DNA03. These are the units I have the most experience with.?ÿ
My DNA03 doesn't like leaves or branches.?ÿ I've learned to avoid using it in situations like that, as it has trouble getting the shots.?ÿ (But I don't use it much these days anyway.)
https://www.nrcan.gc.ca/maps-tools-publications/maps/height-reference-system-modernization/9054
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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.
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NRCAN's PPP system will become a lot more useful for my friends south of the border once uptake of NAPGD2022 takes place IMO.
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.?ÿ?ÿ