I have an infinite 3d elliptical, tilted cone that is defined by a vertex point P(x,y,z) and by 4 angles: the first pair of angles represent the spatial orientation of the cone: θ is the polar angle and φ is the azimuthal angle (in a similar way to the way spherical coordinates are defined). the second pair of angles, α and β, represent the vertical and horizontal "aperture" of the cone (I'm not sure if it's the proper terminology), respectively.

I want to check whether a point U(x2,y2,z1) is inside this cone. How can I do that?

I've found similar questions here, but in those questions the cone was defined differently, and was not tilted. therefore I'm not sure how to apply the previously offered solutions to this problem.

Thank you in advance.


1 Answer 1

  1. Translate $U$ by $-(x,y,z)$
  2. Convert the translated point to spherical coordinates - call the resulting point $(r, t, p)$.
  3. Check if $({t - \theta \over \alpha})^2 + ({p - \phi \over \beta})^2 < 1$
  • $\begingroup$ Could you please elaborate? In step 1, I assume I should translate the point U. In step 2, should I convert the translated point U to spherical coordinates? $\endgroup$ Apr 21, 2015 at 6:17
  • $\begingroup$ Yup. However I just noticed that you want an elliptical cone, updating the answer... $\endgroup$ Apr 21, 2015 at 6:22
  • $\begingroup$ Thank you. the existence of two separate angles, alpha and beta, rather than one angle, means that this cone is necessarily elliptical, or am I wrong? $\endgroup$ Apr 21, 2015 at 6:29

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