# LightRow Axes X/Y/Z

Maybe I’m missing something but I’m pulling my hair out with the axis
configuration for a lightrow. After a lot of fiddling (and reading the SDK)
I’ve finally figured out that for some unknown reason the FS convention is XZ
on the ground plane (instead of XY) and the Y axis is the vertical axis
(instead of Z… why?) Now I’m trying to orient my approach lights to be
angled approximately 4.5 degrees up from horizontal, but for the life of me I
cannot figure out what the rotation axes definitions are. I have tried
everything, from 45 degree increments, flipping orientations by 180 degrees,
but I cannot figure out how these axes are defined (specifically the
rotational axes). The convention I’m used to is X being left/right, Y being
forward/backward, and Z being up/down. But even taking into account the
interesting definition of axes in the SDK, where is 0/0/0 in direction even
pointing? If I put in 0/0/90 my lightrow looks like this:

Makes sense so far. According to
the SDK definition: So now, you
would assume if I set the Y to 180 and keep X 0 and Z at 90, the
unidirectional light would face away from the camera. Nope:
What is going on here?! Am I
really missing something? How is setting Y to 180 degrees not reversing the
direction of these lights?

My post here: https://devsupport.flightsimulator.com/t/3262 Never got a
response so I don’t know if it’s a bug or if the docs are wrong, but it’s not
angles in degrees. It’s xyz coordinates of a point in the middle of the beam.
Think of it like tying a rope to the lamp and pulling it in a direction. This
means 1/1/1 is the same direction as 5/5/5, and it’s a 45 degree angle on both
the vertical and horizontal plane. Edit to add from my linked post:

UNIDIRECTIONAL:

• Light cone is about 90 degrees wide ****
• Position is position in meter, Y/Z/X with X along light row and Z being up.
• Direction is position in meter of a point in the center of the light cone. Y/Z/X with X along light row.

To get a 4.5 degree up angle on the light you probably want something like 1 /
0.079 / 0. If the light is pointing backwards replace 1 with -1. To calculate
the elevation use tan(4.5)=0.079. (Looking at the SDK axis diagram I see that
it would indeed actually be XYZ with z along light row and Y being elevation,
but the coordinate instead of degrees part of my post is correct)

Same here… It seems that something is not working properly