added CH init file (#145)

git-svn-id: http://svn.osgeo.org/metacrs/proj/trunk@2175 4e78687f-474d-0410-85f9-8d5e500ac6b2

1 files changed, 22 insertions, 0 deletions

diff --git a/nad/CH b/nad/CH
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index 00000000..7ae73187
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+# This init file provides definitions for CH1903 and CH1903/LV03
+# projections using the distortion grids developed by Swisstopo.
+# See: http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/lv03-lv95/chenyx06/distortion_grids.html
+#
+# You'll need to download the grids separately and put in a directory
+# scanned by libproj. Directories may be added to the scan list through
+# the PROJ_LIB environment variable
+#
+# Note that an independent effort was made to derive an usable grid
+# from the CH1903->CH1903+ grid initially available from the Swisstopo
+# website. You can read about this other effort here:
+# http://lists.maptools.org/pipermail/proj/2012-February/006093.html
+# It may be of interest because the latter was by some reported as being
+# more accurate than the former:
+# http://lists.maptools.org/pipermail/proj/2012-February/006119.html
+#
+# This init file uses the official one
+#
+# CH1903/LV03
+<1903_LV03>  +proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +k_0=1 +x_0=600000 +y_0=200000 +ellps=bessel +units=m +nadgrids=chenyx06etrs.gsb +no_defs
+# CH1903
+<1903> +proj=longlat +ellps=bessel +nadgrids=chenyx06etrs.gsb +no_defs  <>