Declination Diagram (Arrow) Tool

[JustinOdell]

Hi all,

I have downloaded the Declination Diagram toolbox for ArcGIS 10.2 and am having some difficulties with it's execution.

I follow the instructions provided and have copied the elements into my map.

When running the tool in my projected map (UTM z XX), it does calculate True North and a centroid for my map, however the tool calculates the Magnetic Declination Angle in Decimal Degrees as 'None', and hence it spits out the following:

Magnetic Declination Angle in Decimal Degrees = None

Annual Drift = None

Magnetic Declination Direction = W

Exception : int() argument must be a string or a number, not 'NoneType'

The tool fails to execute.

Can anybody offer any suggestions as to why the tool is calculating the magnetic declination angle as None?

[JustinOdell · Accepted solution]

Well, I was able to answer my own question.

The World Magnetic Model 2015-2020 coefficients were being installed to a separate location, and were not overwriting the existing WMM.xml file that the Declination Tool was looking for.  i.e. I had 2 x WMM.xml files located in different places.

After searching for, and updating the WMM.xml file that the Declination tool uses, everything works as expected.

This has since raised a new problem however, in that my Grid North does not point straight up, but rather True North does, despite the UTM projection...

[SepheFox]

That is normal. The data frame is by default lined up with true north. If you want to rotate it, you can set that under data frame properties, general tab.