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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1answer
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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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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) ...
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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 ...
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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 ...
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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
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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
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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 ...
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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 ...