single parallel Lambert zones
A single-parallel Lambert is equivalent to some two-parallel Lambert.?ÿ If round numbers are used for one, the other may need some extra decimals to match up.?ÿ I heard that in an NGS talk, so you should be able to find the conversion information somewhere on their site.
@bill93 well in at least one, and maybe two software packages I never could get it to work, tried using the two parallel templates with same info for both parallels and anything else I could think of, no joy. I bug one vendor about twice a year, they say it is on the feature list, BUT apparently low priority!
I guess if some of the 2022 SPC zones are going to be single parallel there is hope sometime in the future.
SHG
single parallel Lambert zones
A single-parallel Lambert is equivalent to some two-parallel Lambert.?ÿ If round numbers are used for one, the other may need some extra decimals to match up.?ÿ I heard that in an NGS talk, so you should be able to find the conversion information somewhere on their site.
Here's an old thread on another fouorm where, after some muddle, good references were quoted and Michael Dennis (the master of projections and LDPs) gave an explanation.?ÿ
https://groups.google.com/forum/#!topic/lastools/ipj2kd-GDLo
@bill93 thanks for the link. I personally know Michael and sat in the room with him on the initial Oregon working group on the LDP's about 10 years ago. That still doesn't mean I have the ability to program commercial packages to implement what he suggests 🙂 ie: software that can use a single parallel LCC or as he suggests software that can implement both single and two parallel. Eventually it will happen, but lots of vendors are very slow to react since single parallel LCC are not widespread outside of likely the LDP's that Mr. Dennis had a hand in designing.
Not widespread, but not unknown, either. Special Publication 238 (1947) is a Lambert projection for the entire United States. Instead of being a low distortion projection, it is a high distortion projection. Its purpose was to facilitate calculation of air miles between US cities within an accuracy of less than a mile. Its defining parameters are a central parallel and a scale factor, so it is a single parallel Lambert projection.
It seems to be the same projection as the one in Special Publication 52 (1918), but coordinates don't duplicate exactly from one to the other.
The the air miles calculation is a grid calculation divided by a scale factor, an ellipsoidal distance. Both publications are available here: https://library.noaa.gov/Collections/Digital-Collections/USCGS-Special-Pubs
For a bit of insight into coordinate calculations for single parallel Lamberts, look here: https://surveyorconnect.com/gnss-geodesy/2019/05/02/lambert-meets-limon-an-ldp-at-a-cbl-with-a-quiz-at-the-end/
Won't solve the missing software problem, but a spreadsheet is fairly easy to develop.
