MAPCSLIBRARY Errors and Omissions

[Pointdump]

This is an attempt to list errors and omissions in MAPCSLIBRARY.
The Tern Island 1961 Datum, Code: Tern61, shows an EPSG Code of 6707. It should be >>>EPSG:4707<<<. The EPSG site erroneously also lists the Tern Island 1961 Datum as >>>EPSG:6707-datum<<<, so it's not completely Autodesk's fault. EPSG:6707 should be >>>RDN2008 / UTM zone 32N (N-E)<<<.
To be honest, I don't understand the distinction between a Datum and a GCS(Geographic Coordinate System) in MAPCSLIBRARY. Feel free to school me.

[Pointdump]

Add EPSG:4647 ETRS89/UTM zone 32N (zE-N), as noted in >>>This AKN Article<<<. Topic came up in >>>This Thread<<<.

[O_Eckmann]

Hi @Pointdump ,

In the AKN Article there is a mistake in scale reduction between texte written and screen capture.

In texte it's written 0.996    (only 2 times number 9)

In screen capture there is 0.9996  (3 times number 9)

Which is good?

Olivier

[Pointdump]

Hi Olivier,
I noticed that too. A typo maybe?
I went with the "official" >>>EPSG:4647 ETRS89/UTM zone 32N(zE-N)<<< which shows:
PARAMETER["scale_factor",0.9996]
Dave

[ChicagoLooper]

Duplicate post 

 

[ChicagoLooper]

The author of that AKN will confuse readers. Compare the EPSG codes. The title should show the correct one which is 25832.  The AKN has a typo and shows the wrong one: 28532 

Misinformation? Yes.
Proofreading? Not so much. 

 

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[Pointdump]

@ChicagoLooper,
I noticed that neither EPSG or MAPCSLIBRARY had 28532. I didn't tumble to the switched numbers and just went with ETRS89.UTM-32 in Map's Library. Good eyes.
Dave

[Pointdump]

From >>>this post<<<, to fix >>>this -32,000,000 Meter problem<<<, add >>>EPSG:4647<<< to MAPCSLIBRARY. Workaround for now is to add as shown >>>here<<<.

Edit: This post is a duplicate of an earlier post, but with more info and links.

[Pointdump]

Hover your cursor over the "Elliposid" symbol. Oopsie!
I'm using 2022, so this might have been corrected in 2023.
Dave

[Pointdump]

Amtrak Coordinate System. From >>>This Request<<<.
I found details >>>Here<<<.

[Pointdump]

With the nice Transformation Tool in Civil 3D being able to, in theory, transform vertical datums, MAPCSLIBRARY should include coordinate system with vertical definitions. Like >>>EPSG:6653<<<, NAD83(CSRS) / UTM zone 10N + CGVD2013 height. When I do a search for EPSG:6653, MAPCSLIBRARY shows ITRF94 Datum. But ITRF94 should be >>>EPSG:8994<<<.
If I search for NAD83(CSRS)/UTM zone 10N, I find CSRS.UTM-10N, which shows EPSG:3157. But let's compare WKT listings.
MAPCSLIBRARY:
TOWGS84[0.0000,0.0000,0.0000,0.000000,0.000000,0.000000,0.00000000]
EPSG:
TOWGS84[-0.991,1.9072,0.5129,-1.25033E-07,-4.6785E-08,-5.6529E-08,0]
Transformation to WGS84 should use the CSRS GSB file for British Columbia, so at this point my head is spinning.

[Pointdump]

From >>>This Thread<<<, the StevensMN-F Coordinate System is not correct.
The coordinate system definition >>>Here<<< agrees with >>>ESRI:103783<<<. There are 2 problems with the MAPCSLIBRARY definition. First one is easy to fix. The extents are just flat wrong and don't cover Stevens County, Minnesota at all.

The second problem is that Minnesota uses a different size Ellipsoid than NAD83:
Semi-major Axis (meters): 6378502.761
Semi-minor Axis (meters): 6357116.84

[Pointdump]

Definition of Terms are wrong in the Definition of GRS1980 Ellipsoid.
Equatorial radius should be Semimajor axis of the geodetic ellipsoid
Polar radius should be Semiminor axis of the geodetic ellipsoid
I know that's a quibble. I'm getting my terms and formulas from James Stem's white paper >>>Here<<<.
Inverse flattening should be just "flattening"
Flattening is not 0.00335281068118332. It is 0.00335281068118329
Eccentricity squared shows 0.0818191910428279. This number should be called First eccentricity.

And Eccentricity squared should indicate whether it is First or Second Eccentricity squared.
First Eccentricity Squared = (a^2 - b^2)/a^2 = 2f - f^2 = 0.0066943800229028
Second Eccentricity Squared = (a^2 - b^2)/b^2 = e^2 /1 - e^2 = 0.0067394967754810
First eccentricity of the ellipsoid = sqrt(2f-f^2) =0.0818191910428277

[Pointdump]

Still misspelling Ellipsoid as "Elliposid" in 2023 MAPCSLIBRARY.
Dave

[Pointdump]

Unable to define projection parameters with "Oblique Mercator" projection in MAPCSLIBRARY. Page is blank.

[Pointdump]

Problem posted >>>Here<<<.
PT-TM06/ETRS89 is a bad definition in MAPCSLIBRARY.
ETRS89/PT-TM06 more closely matches >>>EPSG:3763<<<.

[rmacan]

I stopped holding my breath for EPSG:6150 over five years ago. It's almost like it's....no one's job.

[Pointdump]

Hi Randy,
Civil 3D and Map 3D can't do anything with the vertical part of a Compound Coordinate System like >>>EPSG:6150<<<, but you can add the horizontal part as a custom coordinate system. Strangely, if you punch in 6150 in MAPCSLIBRARY you get 2 listings for datums, neither of which is EPSG:6150.
While more coordinate systems are added each release, Autodesk really needs to have someone go through MAPCSLIBRARY from top to bottom and correct things like this.
Dave

[Pointdump]

The Library doesn't have >>>EPSG:6703<<<, noted in >>>This Post<<<.

[Pointdump]

The Library erroneously notes the WGS84 Datum as being EPSG:6326. It should be 4326. (There is no 6326 listed in the EPSG site)

[Pointdump]

MAPCSLIBRARY erroneously notes the NAD83 Datum as being EPSG:6269. It should be >>>4269<<<. In the EPSG registry >>>6269<<< refers to the MAGNA-SIRGAS / San Jose del Guaviare urban grid.