[OpenLayers-Users] ArcGIS Online Cached tiles datum shift
Vadim Bokin
vbokin at gmail.com
Mon Jul 19 19:53:06 EDT 2010
Hi,
Does anyone have the _exact_ proj4js definition for ESRI projections
EPSG:102100 and the older EPSG:102113?
My maps have a y-coordinate shift (both north and south at different zooms)
off by many map pixels. Always close, but no cigar. X-coordinate is always
dead on.
I can add in ArcGIS online content as dynamic layer without any problems.
But when adding cached tiles, there's always this shift. Has anyone seen
this before and/or been able to resolve it? I need to be able to use the
cached tiles.
I've used the one from spatialreference.org, as well as set it directly to
be equal to Google's EPSG:900913 but there's always a shift. I've tried
many different variations with +a and +rf and others but I feel like the
definition is missing a +towgs84=... adjustment to properly correct for the
shift on the map but I have no way of knowing what those parameters should
be and whether it should be the 3-parameter adjustment or the 7-parameter
one.
Here's my current definition:
Proj4js.defs["EPSG:102100"] = "+proj=merc +lon_0=0 +x_0=0 +y_0=0 +a=6378137
+b=6378137 +units=m +nadgrids=@null";
+towgs84=0,0,0,0,0,0,0 doesn't help, but I feel like the right values in
there will fix the problem.
Thank you,
-Vadim
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