Model orientation / azimuth calculations

Questions
1

Hello everyone!
is it possible to get somehow model orientation from the .glb file? I need to know where the north is. Or maybe there is some information in the scene about it?

2

Well, where is north? Do we say that (0,0,1) is north?

Then you can get the mesh rotation and see how it compares

3

Alright, I’ll check this tomorrow. I need it to calculate azymuth

Basically what I need to do is to calculate alfa angle.

image

Observer(black dot) is a mesh and orange dot is also a mesh in my case.

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4

I think what @Deltakosh ment is, there is no predefined correct rotation or n/s/e/w.
everything is relative :wink: north is where ever you choose it is compared to the rest of your scene.

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5

Totally. Basically in your case you can do the dot vector of (0,0,1) and the vector from a to b(you need to normalize it)

It will give you the cos of the azimuth so Math.acos will give you your angle

2 Likes
6

@Deltakosh, your comment was very helpful, I think I’m really close to the solution. What’s more, I found that (0, 0, -1) vector is the north in my model. But I came across two problems I couldn’t solve.

https://playground.babylonjs.com/#HZXM1I#5

  1. I think azimuth shouldn’t be changing when dragging Y axis.
  2. Your calculations are very good but it doesn’t work for the 0-360° range but for 0-180°. What I mean is when we put the red spheres(alfa = beta in this case) like in the image below they gonna have the same azimuth but it shouldn’t be the same…
    image
    image632×595 25.9 KB

    should be something like this:
    image
    image630×589 28.1 KB

    sorry for my bad drawings :slight_smile:
7

I think the sign of the dot should give you the quadrant (0,0,1).(0,0,-1) will return -1

8

I managed to fix previously mentioned two issues :slight_smile: Maybe not exactly in the mathematical way but I guess it gonna work well.

here’s the playground if someone ever needs it:
https://playground.babylonjs.com/#HZXM1I#7

1 Like