True north-based azimuths

Can I automatically find True north-based azimuths based on certain value of an azimuth from a refference point ?

Let's say if I have a value of 90 the result will be East, I have a value of 25 the result will be North-northeast.

I could do a function but maybe there's more easier methodes.

Thank you!

Answer 1

[Bjorn Gustavsson]

Your question doesn't make much sense, sure you can do that - but that would be more of "establishing" your azimuth-convention. If you are thinking of calculating the azimuth clockwise from North to a point [x,y] from a point [x0,y0]. Then atan2 should be your friend:

phi = atan2(x0-x,y0-y);

Or atan2d if you directly want the angle in degrees - which I've found to be a dangerous habit to use, it is in my experience strongly preferable to have all angles in radians and convert to degrees when displaying.

HTH

[Cristian Martin]

Bjorn, I mean Cardinal points, sorry. Based of an specified azimuth. If the az=90 result be East.

[Bjorn Gustavsson]

What is your problem? Do you want to convert a set of azimuth-angles relative to some cardinal direction to an azimuth clockwise from north?

[Cristian Martin]

I think my question was not so clear, excuse me.

Let's say I have:

Coord 1:

lat1 = value 1 in dm;

lon1 = value 2 in dm;

Coord 2:

lat2 = value 3 in dm;

lon2 = value 4 in dm;

The azimut from coord 1 to coord 2 is 45 degree. Matlab has a command for displaying cardinal point in this case Northeast ?

I have found something but I don't know how to adapt it in my case

directionValues = 0:22.5:337.5;

directionNames = {'N','NNE','NE','ENE','E','ESE','SE','SSE','S','SSV','SV','VSV','V','VNV','NV','NNV'};

directionValues(strcmp(directionNames,'V'));

[Bjorn Gustavsson]

If you want to display the label from directionNames with the directionValues closest to an arbitrary angle, phi, you only have to determine the "best matching direction". You can for example do this:

dl2 = ((cosd(phi)-cosd(directionValues)).^2 + ...
       (sind(phi)-sind(directionValues)).^2); % should be robust to wrap-arounds
[dl,idx_best] = min(dl2);
disp(directionNames);

HTH

[Cristian Martin]

Thanks Bjorn !