Database: update to EPSG 10.088

[rouault]

The import script has been modified to avoid import errors on the following Danish CRS:

• Skipping EPSG:10258 GS reconstruction east-orientated as we do not handle yet projection method EPSG:1102 / Lambert Conic Conformal (1SP variant B)
• Skipping EPSG:10262 GSB reconstruction east-orientated as we do not handle yet projection method EPSG:1102 / Lambert Conic Conformal (1SP variant B)
• Skipping EPSG:10266 KK reconstruction east-orientated as we do not handle yet projection method EPSG:1102 / Lambert Conic Conformal (1SP variant B)

CC @busstoptaktik Looking at EPSG revision history, it appears you're the one having submitted the above CRS to IOGP. Currently we don't import them into proj.d as the projection method EPSG:1102 / Lambert Conic Conformal (1SP variant B) is not mapped to a PROJ map projection. Do you have a plan doing that ?
I also see new grids being added. I guess you'll submit them to PROJ-data ?

[busstoptaktik]

EPSG:1102 / Lambert Conic Conformal (1SP variant B) is not mapped to a PROJ map projection

The expected PROJ expressions are:

GS:  proj=lcc   ellps=danish lon_0=10.37775   lat_0=55   lat_1=56
GSB: proj=lcc   ellps=danish lon_0=14.92775   lat_0=55   lat_1=56 x_0=-18831.460 y_0=5614.621
KK:  proj=lcc   ellps=danish lon_0=10.37775   lat_0=55   lat_1=56

If the problem relates to whether PROJ implements Variant A (EPSG:9801) or Variant B (EPSG:1102), I did actually check whether PROJ implements one or the other prior to submitting the material to EPSG. I did so by checking the examples from the IOGP Guidance Note 7.2, and as shown below, PROJ implements Variant B (EPSG:1102).

LCC 1SP, Variant B: Example from "IOGP Publication 373-7-2 – Geomatics Guidance Note number 7, part 2 – May 2022, section 3.4.1.3, p. 23"

Parameters

Latitude  of natural origin: 44+(22+45/60)/60 = 44.37916666666666667
Latitude  of false   origin: 45+11/60         = 45.18333333333333333
Longitude of false   origin:  6+49/60         =  6.81666666666666667

Easting at false origin: 150000 m
Northing at false origin: 50000 m

Test point

Latitude: 47 N
Longitude: 7 E

PROJ implementation:

echo 47 7 | proj -srf %.4f +proj=lcc +ellps=GRS80 +lat_1=44.37916666666666667 +lat_0=45.1833333333333333 +lon_0=6.816666666666666667 +x_0=150000 +y_0=50000

Result N,E:   252043.3067 163958.3661
Expected N,E: 252043.307  163958.366

Conformance! - i.e. PROJ implements variant B

LCC 1SP, Variant A: Example from "IOGP Publication 373-7-2 – Geomatics Guidance Note number 7, part 2 – May 2022, section 3.4.1.2, p. 22"

Parameters

Latitude  of natural origin: 18 N
Longitude of natural origin: 77 W
False easting  250000 m
False northing 150000 m

Test point

Latitude:  17+(55+55.80/60)/60 = 17.932166666666666667 N
Longitude: 76+(56+37.26/60)/60 = 76.943683333333333333 W

PROJ implementation:

echo 17.932166666666666667 76.943683333333333333 | proj -srf %.4f +proj=lcc +ellps=clrk66 +lat_1=18 +lat_0=18 +lon_0=-77 +x_0=250000 +y_0=150000

Result N,E:  6533195.6266   14749527.0037
Expected N,E: 142493.51       255966.58

Discrepancy - i.e. PROJ does not implement "Variant A"

I also see new grids being added. I guess you'll submit them to PROJ-data ?

Your guess is correct :-)

The process with registering old Danish systems with EPSG has been extremely long an winded, but the grids have already been available from the SDFI ftp-server for some time now.

[rouault]

Discrepancy - i.e. PROJ does not implement "Variant A"

Ouch, I almost had a heart attack reading this given this is a widely used method, but you just got the numerical application wrong, with the sign of the input longitude :-) Here's the correct input that shows we are conformant:

$ echo 17.932166666666666667 -76.943683333333333333 | bin/proj -srf %.4f +proj=lcc +ellps=clrk66 +lat_1=18 +lat_0=18 +lon_0=-77 +x_0=250000 +y_0=150000
142493.5110	255966.5818

The good news is that the mapping of LCC_1SP variant B to +proj=lcc is trivial. I'll look at adding the mapping part

[busstoptaktik]

numerical application wrong,

Thanks for noticing - never a good idea trying to reconstruct year-old computations at 6 in the morning after a sleepless night :-) ... the sheer amount of offset should obviously have told me, especially since it is just a few days ago, I diagnosed a similar case in connection with some old Greenlandic Systems.

In other words, the PROJ implementation is conforming for both Variant A and B, the difference is exclusively in the selection of parameters.

Originally, I probably tried variant B only, concluded it was PROJ compatible, then proceeded using it for the relevant parts of the "reconstruction of old Danish systems" project.

[rouault]

Support for LCC 1SP Variant B added in extra commit:

$ PROJ_DATA=data bin/projinfo EPSG:10262
PROJ.4 string:
+proj=lcc +lat_1=56 +k_0=1 +lat_0=55 +lon_0=14.92775 +x_0=-18831.46 +y_0=5614.621 +a=6377019.27 +rf=300 +units=m +no_defs +type=crs

WKT2:2019 string:
PROJCRS["GSB reconstruction east-orientated",
    BASEGEOGCRS["GSB-IRF",
        DATUM["Generalstabens System Bornholm Intermediate Datum",
            ELLIPSOID["Danish 1876",6377019.27,300,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        ID["EPSG",10260]],
    CONVERSION["GSB-reconstruction",
        METHOD["Lambert Conic Conformal (1SP variant B)",
            ID["EPSG",1102]],
        PARAMETER["Latitude of natural origin",56,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8801]],
        PARAMETER["Scale factor at natural origin",1,
            SCALEUNIT["unity",1],
            ID["EPSG",8805]],
        PARAMETER["Latitude of false origin",55,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8821]],
        PARAMETER["Longitude of false origin",14.92775,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8822]],
        PARAMETER["Easting at false origin",-18831.46,
            LENGTHUNIT["metre",1],
            ID["EPSG",8826]],
        PARAMETER["Northing at false origin",5614.621,
            LENGTHUNIT["metre",1],
            ID["EPSG",8827]]],
    CS[Cartesian,2],
        AXIS["(E)",east,
            ORDER[1],
            LENGTHUNIT["metre",1]],
        AXIS["(N)",north,
            ORDER[2],
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Geodesy, topographic mapping."],
        AREA["Denmark - Bornholm onshore."],
        BBOX[54.94,14.59,55.38,15.25]],
    ID["EPSG",10262]]

[kbevers]

Looks good to me. I'll add the grids to PROJ-data within the next couple of days.

[kbevers]

@rouault the first commit can be backported, right?

[rouault]

the first commit can be backported, right?

yes, I see I forgot to add the backport tag. Will do manually. actually I intended to backport both commits, unless you want otherwise.

[kbevers]

actually I intended to backport both commits, unless you want otherwise.

I think it's fine. I figured you didn't add the backport tag because the second commit sort of introduces new functionality. I agree that backporting both is suitable.