[GRASSLIST:1703] Re: v.proj bug?

[Hamish]

> I have a raster dataset in the old New Zealand South Island grid 
> (Transverse Mercator: central meridian 171.5E, latitude of origin 44S,
> scale 1, false easting 500000, false northing 500000, units yards, 
> ellipse international). This projection is included in ArcMAP and when
> I compare a graticuled map in ArcMAP to (coarse scaled) printed grid
> of the raster  for the dataset, there is a very close match.

I have this definintion (from "concord"):

SNAT "South Island National Grid (yards)" REF_FRAME NZGD1949 &
          PROJECTION TM 171.5 -44 1.00000 500000.0 500000.0 0.91439841 &
          RANGE 0 0 800000 1000000


No time to look into this right now, but you might compare against what
"concord" gives: [runs fine under wine]

http://www.linz.govt.nz/rcs/linz/pub/web/root/core/SurveySystem/GeodeticInfo/Software/snapdownload/index.jsp

That "should" give a correct answer....



** Check if you are using the correct parameters for the NZGD49 datum:
[use GRASS 5.3+]

src/libes/gis/datum.table
src/libes/gis/datumtransform.table
----------------------------------

http://www.linz.govt.nz/rcs/linz/pub/web/root/core/SurveySystem/GeodeticInfo/GeodeticDatums/nzgd49tonzgd2000/index.jsp
nzgd49 "New_Zealand_Geodetic_Datum_1949" international dx=54.4  dy=-20.1  dz=183.1


http://www.linz.govt.nz/rcs/linz/pub/web/root/core/SurveySystem/GeodeticInfo/Software/snapdownload/index.jsp
nzgd49 "nadgrids=nzgd2kgrid0005.gsb" "New Zealand" "LINZ NZGD49 NTv2 Distortion Model, accuracy 10-30cm"


http://www.linz.govt.nz/rcs/linz/6149/osgpol97_3.pdf
nzgd49 "towgs84=59.47,-5.04,187.44,0.47,-0.1,1.024,-4.5993" "New Zealand" "Accuracy approx. 4m"


I'll get around to looking into this at some point, but can't now.

Curious to know what the data is & where it's from..



regards,
Hamish
(way way down on the South Island, New Zealand)