Questions tagged [convergence]
meridian convergence is the angle between true north (i.e., the direction of local meridian) and grid north (i.e., the grid's Y-axis)
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questions
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1answer
145 views
Calculating Grid Convergence
When ESRI tool "Calculate Grid Convergence Angle (Cartography)" is used to calculate line bearing or azimuth, is the bearing referenced to True North or Grid North?
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votes
1answer
246 views
Calculating convergence angle for point data in QGIS
I have been a user of ArcGIS Desktop for many years and this function is easily done within ArcMap using the 'Calculate Grid Convergence Angle (Cartography)' tool.
I am wondering if there is a ...
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0answers
113 views
proj4js: calculate meridian convergence
Given a projection and coordinates of a single point, how do I calculate the meridian convergence at that point?
Is it even possible? I'm unable to find anything useful using Google.
If it is not ...
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0answers
237 views
Precision Ag and UTM declination
I've written an open source Precision Agriculture application called AgOpenGPS that does everything from auto steer, to mapping, implement and section turn on/off, auto headland turns and more. It's ...
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0answers
145 views
Calculate Grid Convergence Angle within ModelBuilder Model
I am trying to use the 'Calculate Grid Convergence Angle" tool (from Cartography toolbox -> Data Driven Pages) into ModelBuilder. The tool is pretty simple -
(1) import,
(2) remove no data
(3) ...
1
vote
1answer
526 views
Grid convergence
I was trying to overlay the British National Grid (OSGB 1936 UTM projection) onto the Eurostat grid (ETRS 1989 LAEA Europe) and realized that they do not perfectly overlay (after projecting the ...
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0answers
106 views
meridian convergence local coordinate systems [duplicate]
I am new to the concept of meridian convergence. I understand that it is the angle between True North and Grid North. But I have problems understanding how
meridian convergence affects local ...
3
votes
2answers
2k views
How SAGA calculates Convergence Index
I have calculated convergence index on my DEM with SAGA.
Output results seems to be ok (values in range -100;100), but I don't understand how it works.
Here is some sample data from my DEM:
I know ...
8
votes
5answers
30k views
Calculating grid convergence (True North to Grid North)
I would like to know how to calculate the grid convergence angle between True North and Grid North for UTM maps.
I am using ArcGIS 10.0 (ArcView licence). and have used the Calculate Grid Convergence ...
3
votes
1answer
675 views
Declination Diagram
What point on a UTM map does the declination diagram refer to? Is it the centre? Is it the edges? Is there a standard?
The central meridian on a UTM map points to true north. Are grid north and true ...
5
votes
1answer
14k views
Applying proper conversion from True to Grid bearing
Assume that Grid North is 1.49 deg W of True North.
Also, the magnetic declination is 13.11 deg.
If I wanted to take gyroscopic surveys (measured from True North) and then convert them to Grid ...
4
votes
2answers
10k views
How to Calculate North?
I am working on a field survey and a client requirement is to differentiate various norths, like magnetic north, true north and grid north. My question is what is the methodology of calculating north ...
