Hi,
Using the C# GDAL FileGDB API V 1.5 (https://trac.osgeo.org/gdal/wiki/FileGDB)
I have written a simple test application which writes and rereads a polygon
geometry. The test FileGDB is using WKID 21781 (CH1903_LV03), XYScale of
20'000 and XYTolerance of 0.0004.
Using the test application I have written a polygon with the following
coordinates
POLYGON((
660440.402 232655.598,
660419.723456789 232646.789153456,
660398.588123 232712.410135,
660477.806 232751.485, ...))
Reading the polygon using OgrInfo gets following coordinates
MULTIPOLYGON (((
660440.402 232655.598,
660419.723450001 232646.78915,
660398.588100001 232712.410149999,
660477.806 232751.485, ...)))"
Rereading the geometry using the C# Esri.FileGDBAPI gets following coordinates
point[0] 660440.40199999884 232655.59800000116
point[1] 660419.72345000133 232646.78914999962
point[2] 660398.58810000122 232712.41014999896
point[3] 660477.80600000173 232751.4849999994
...
Regarding the XYScale of 20'000 it is correct that the position 660398.588123
is altered to 660398.58810. But considering the value of 660398.588100001 the
coordinates seems not to be stored as whole numbers.
Using the Esri.FileGDBAPI the values differ even more. It seems to be a
floating point accuracy problem but I don't really understand why. How are the
coordinates stored in FileGDB and why does the read values differ between
OgrInfo and Esri.FileGDBAPI?
Thanks in anticipation
Benno Wiss
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