I think what you are looking for is exactness, which doesn't exist regardless of which coordinate system you are using. All surveyors measure differently (which procedures and statistical analysis is used) which was alluded to in a previous post by Math Teacher.
You've probably decided what to do, but here are some things that might be helpful going forward. First, CA Zone 6 state plane is defined by NGS, so you want a projection that duplicates the NGS definition:
Second, it's likely that you want survey feet, so EPSG:2771, EPSG:3499, and EPSG:26946 would be eliminated, because they are in meters. Otherwise, they are identical, so if meters is ok, any one of them is ok.
The other three are identical as well, so any of them is ok, but you should be aware of a minor shortcoming in each. To see it, go to your reference list website:
https://spatialreference.org/ref/?page=1&search=California+Zone+6 ?ÿ ?ÿ
Select 2230 and click on Proj4. This will show the part of the WKT file that the coordinate engine uses. Note that +x_0 and +y_0 do not exactly match the NGS definition values for E0 and Nb. To see why, click on WKT as HTML back at the reference website and note the values for false easting and false northing. They are?ÿ feet rounded to 3 decimals. Converted back to meters for use in Proj4, there's a bit of a discrepancy that shifts the projection origin slightly, not enough to matter for most applications, but you have to be the judge of that. It's not an issue in the esri version because feet are carried to many more decimal places in the WKT file.
One other thing to note is that little WKT line +TOWGS84 that sometimes appears. If it's not followed by all zeros, then Proj4 will apply a transformation to the coordinate system.?ÿ It's not an issue here, but it's one more thing that needs to be checked when choosing a projection.
My first choice would be the esri version, otherwise any of the other three will do.
But what about the different realizations of NAD83? Well, state plane coordinates result from a rigorous mathematical process applied to lat/lon coordinates. The point 33?ø N, 107?ø W will always produce the same state plane coordinates regardless of the realization. So the burden of not mixing coordinates from different realizations is squarely on the user.
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This site is absolutely the greatest thing since sliced bread!
EPSG codes are just a way to embed meta data in your zone. The underlying SPC parameters are all the same for a given zone because the definition of NAD83 is the same over time, the realization on the face of the earth is what changes.
As a surveyor, I have to deal with picking the correct EPSG zone about once in 40 years, I can get correct data on a map without relying on an EPSG code.
Math Teacher's post just above has some good info!!!
SHG
If you are a GIS guy, listen to Melita.?ÿ 99% of the world will consume your PRJ with an ESRI formed projection which will include the datum tag.?ÿ Lambert Conformal, from my days listening to multiple Michael Dennis (NGS geodesist) presentations reduce issues, including the ones we have in Alaska(East-West).
If your basing this on ''Best" for GPS data, tied to CORS, then use the published CORS coordinates in NAD83(2011) Epoch 201o.?ÿ?ÿ
Joel
If you are a GIS guy, listen to Melita.?ÿ 99% of the world will consume your PRJ with an ESRI formed projection which will include the datum tag.?ÿ Lambert Conformal, from my days listening to multiple Michael Dennis (NGS geodesist) presentations reduce issues, including the ones we have in Alaska(East-West).
If your basing this on ''Best" for GPS data, tied to CORS, then use the published CORS coordinates in NAD83(2011) Epoch 201o.?ÿ?ÿ
Joel
