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phitheta2uv

Convert phi/theta angles to u/v coordinates

Description

example

UV = phitheta2uv(PhiTheta) converts the phi/theta angle pairs to their corresponding u/v space coordinates.

Examples

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Find the corresponding u-v representation for φ = 30° and φ = 0°.

uv = phitheta2uv([30; 0])
uv = 2×1

     0
     0

Input Arguments

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Phi and theta angles, specified as a two-row matrix. Each column of the matrix represents an angle in degrees, in the form [phi; theta].

Data Types: double

Output Arguments

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Angle in u/v space, returned as a two-row matrix. Each column of the matrix represents an angle in the form [u; v]. The matrix dimensions of UV are the same as those of PhiTheta.

More About

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Phi Angle, Theta Angle

The phi angle (φ) is the angle from the positive y-axis to the vector’s orthogonal projection onto the yz plane. The angle is positive toward the positive z-axis. The phi angle is between 0 and 360 degrees. The theta angle (θ) is the angle from the x-axis to the vector itself. The angle is positive toward the yz plane. The theta angle is between 0 and 180 degrees.

The figure illustrates phi and theta for a vector that appears as a green solid line.

The coordinate transformations between φ/θ and az/el are described by the following equations

sinel=sinϕsinθtanaz=cosϕtanθcosθ=coselcosaztanϕ=tanel/sinaz

U/V Space

The u/v coordinates for the hemisphere x ≥ 0 are derived from the phi and theta angles.

The relations are

u=sinθcosϕv=sinθsinϕ

In these expressions, φ and θ are the phi and theta angles, respectively.

In terms of azimuth and elevation, the u and v coordinates are

u=coselsinazv=sinel

The values of u and v satisfy the inequalities

1u11v1u2+v21

Conversely, the phi and theta angles can be written in terms of u and v using

tanϕ=u/vsinθ=u2+v2

The azimuth and elevation angles can also be written in terms of u and v

sinel=vtanaz=u1u2v2

Extended Capabilities

Introduced in R2012a