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# reprojecting bearings

1824
2
04-24-2012 01:37 PM
Deactivated User
Hi,

So I have a point dataset on circulation for the whole world. The data is unprojected. One of the attributes is a bearing for the atmospheric circulation, with a compass direction.

Now I want to reproject this, to for instance Winkel III - is there any way to reproject it so that the value 0 in the bearing attribute still points towards north? Reprojecting the location of the points is simple, the crux is how to recalculate the bearings!

Hope you understand what I mean!

Any tips are welcome!
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1 Solution

Accepted Solutions
Honored Contributor
What I think you want is to convert the true north value to a new field with a grid based bearing.
If this is the problem you are in luck - there is a command for that! Not sure when it appeared 10.0(?)
That refers to an earlier obsolete tool Calculate Geodesic Angle if you are still on 9.x

CalculateGridConvergenceAngle_cartography (in_features, angle_field, {rotation_method}, {coordinate_sys_field})
2 Replies
Honored Contributor
What I think you want is to convert the true north value to a new field with a grid based bearing.
If this is the problem you are in luck - there is a command for that! Not sure when it appeared 10.0(?)
That refers to an earlier obsolete tool Calculate Geodesic Angle if you are still on 9.x

CalculateGridConvergenceAngle_cartography (in_features, angle_field, {rotation_method}, {coordinate_sys_field})
Deactivated User
What I think you want is to convert the true north value to a new field with a grid based bearing.
If this is the problem you are in luck - there is a command for that! Not sure when it appeared 10.0(?)
That refers to an earlier obsolete tool Calculate Geodesic Angle if you are still on 9.x

CalculateGridConvergenceAngle_cartography (in_features, angle_field, {rotation_method}, {coordinate_sys_field})

Excellent, thanks - just what I was looking for. Then I would have to give up the projection that I am currently using though (Wagner VII, which I use Global Mapper to project the data to) and using something else - but I can live with that. I didn't a quick search through the documentation, but I must have missed this one.