[Proj] Creating a nadgrid shift file

Mon Jan 21 03:30:18 PST 2013

Hi Andre, could you send me the gsb-file you made, so I can have a look 
at the coordinates and values?

Jan

On 01/20/2013 07:28 PM, Andre Joost wrote:
> Hi,
>
> I think I found a solution, if I have understood your test data correct:
>
> What you have and what you want:
>
> source:
>    id |  lon   |   lat   | deg E |  deg N |   dms E  | dms N
> ----+--------+---------+-------+--------+----------+----------+
>    ll | 5.3876 | 52.1561 | 19395 | 187762 | 5d23'15" | 52d9'22"
>    lr | 5.4022 | 52.1561 | 19448 | 187762 | 5d24'08" | 52d9'22"
>    ur | 5.4022 | 52.1651 | 19448 | 187794 | 5d24'08" | 52d9'54"
>    ul | 5.3876 | 52.1651 | 19395 | 187794 | 5d23'15" | 52d9'54"
>
> destination:
>    id |  lon   |   lat   | deg E |  deg N |   dms E  | dms N
> ----+--------+---------+-------+--------+----------+----------+
>    ll | 5.37299| 52.14711| 19343 | 187730 | 5d22'23" | 52d8'50"
>    lr | 5.41681| 52.14711| 19501 | 187730 | 5d25'1"  | 52d8'50"
>    ur | 5.41682| 52.17409| 19501 | 187826 | 5d25'1"  | 52d10'27"
>    ul | 5.37298| 52.17409| 19343 | 187826 | 5d22'23" | 52d10'27"
>
> I expanded the data a bit:
> S 52.13811°N =187697"N
> N 52.18309°N =187859"N
> E -5.43142°E =-19553"E
> W -5.35838°E =-19290"E
> with zero values for the border cells
>
> My ASCII ntv2 file has the following header:
>
> NUM_OREC 11
> NUM_SREC 11
> NUM_FILE  1
> GS_TYPE SECONDS
> VERSION
> SYSTEM_F
> SYSTEM_T
> MAJOR_F        0.000
> MINOR_F        0.000
> MAJOR_T        0.000
> MINOR_T        0.000
> SUB_NAME
> PARENT  NONE
> CREATED
> UPDATED
> S_LAT     187697.000000
> N_LAT     187859.000000
> E_LONG    -19553.000000
> W_LONG    -19290.000000
> LAT_INC       32.400000
> LONG_INC      52.600000
> GS_COUNT    36
>
> dx and dy are swapped in the file, upper right first, and dx values
> inverted:
> -32.370100 -52.59180  0.000000  0.000000
> -32.363600 52.602400  0.000000  0.000000
>     32.35040 -52.64480  0.000000  0.000000
>     32.35610 52.634210  0.000000  0.000000
> (and a lot of null value lines between)
>
> Converted with GDAy, because the old GDAit won't run on Windows 7
> anymore :-(
>
> For cs2cs, I made an input file with your WGS84 values, and used
> Amersfoort lat/lon instead of the projected CRS.
>
> Put the following in a batch file:
>
> echo epsg4326 RDgrid.txt >out.txt
> cs2cs +init=epsg:4326 +to +proj=longlat +ellps=bessel
> +nadgrids=D:\Karten\gdal\ntv2\RD.gsb +no_defs RD-grid.txt >>out.txt
>
> echo Amersf ll nowgs84 - grid >>out.txt
> cs2cs +proj=longlat +ellps=bessel +towgs84=0,0,0,0,0,0,0 +no_defs +to
> +proj=longlat +ellps=bessel +nadgrids=D:\Karten\gdal\ntv2\RD.gsb
> +no_defs RD-grid.txt >>out.txt
>
> echo Amersf ll - grid >>out.txt
> cs2cs +proj=longlat +ellps=bessel
> +towgs84=565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725
> +no_defs +to +proj=longlat +ellps=bessel
> +nadgrids=D:\Karten\gdal\ntv2\RD.gsb +no_defs RD-grid.txt >>out.txt
>
> echo grid -   Amersf ll nowgs84 >>out.txt
> cs2cs +proj=longlat +ellps=bessel +nadgrids=D:\Karten\gdal\ntv2\RD.gsb
> +no_defs +to +proj=longlat +ellps=bessel +towgs84=0,0,0,0,0,0,0 +no_defs
> RD-grid.txt >>out.txt
>
> echo grid 2 Amersf ll >>out.txt
> cs2cs +proj=longlat +ellps=bessel +nadgrids=D:\Karten\gdal\ntv2\RD.gsb
> +no_defs +to +proj=longlat +ellps=bessel
> +towgs84=565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725
> +no_defs RD-grid.txt >>out.txt
>
> gives this result:
> epsg4326 RDgrid.txt
> 5d23'15.36"E	52d9'21.96"N 0.000
> 5d24'7.92"E	52d9'21.96"N 0.000
> 5d24'7.92"E	52d9'54.36"N 0.000
> 5d23'15.36"E	52d9'54.36"N 0.000
> Amersf ll nowgs84 - grid
> 5d23'15.36"E	52d9'24.046"N -698.431
> 5d24'7.92"E	52d9'24.046"N -698.431
> 5d24'7.92"E	52d9'56.446"N -698.420
> 5d23'15.36"E	52d9'56.446"N -698.420
> Amersf ll - grid
> 5d23'13.793"E	52d9'18.402"N 43.347
> 5d24'6.345"E	52d9'18.402"N 43.346
> 5d24'6.345"E	52d9'50.798"N 43.331
> 5d23'13.793"E	52d9'50.799"N 43.331
> grid -   Amersf ll nowgs84
> 5d22'23.077"E	52d8'47.83"N 698.441
> 5d25'0.512"E	52d8'47.823"N 698.441
> 5d25'0.565"E	52d10'24.624"N 698.411
> 5d22'23.046"E	52d10'24.63"N 698.411
> grid 2 Amersf ll
> 5d22'24.637"E	52d8'53.47"N -43.360
> 5d25'2.095"E	52d8'53.464"N -43.359
> 5d25'2.148"E	52d10'30.276"N -43.313
> 5d22'24.606"E	52d10'30.282"N -43.314
>
> Compared to the start, the "grid 2 Amersfoort" is the way to get the
> desired coordinates. Don't ask me why...
>
> Maybe a case of "If you give me rubbish, I do nothing"-behaviour of proj.
>
> HTH,
> André Joost
>
>
>
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