# Radar Approach – Testing Points II

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Up to this point the required computations to compute the value of *p* in the camera referential coordinates, *pc* have been detailed. It is also assumed at this point that the pc.z has a value that is between *nearDist* and *farDist*, so its time to check the other coordinates, namely *pc.y* and *pc.x*.

Consider now a side view of the frustum in 2D to simplify the diagram. The horizontal arrow shows the value of *pc.z*. At that distance from the camera, *pc.z* the view frustum has a height *h*.

where *a* is the vertical field of view angle.

This implies that, for the Y coordinate of *pc* to be inside the view frustum,

-h/2<pc.y<h/2

or, in algorithmic style,

if (-h/2 > pc.y || pc.y > h/2) return(OUTSIDE)

The width of the frustum can be computed based on the height as

w=h*ratio;

So the X component of pc can be tested with the following *if* statement:

if (-w/2 > pc.x || pc.x > w/2) return(OUTSIDE)

The following figure, although a little bit complex ( ;-> ) provides some information about the components of *pc*.

This method should be faster than the previous approaches where six planes are tested. In here, only a dot product is performed for each pair of planes, whereas in the previous approaches a dot product was performed for every plane, in the worst case scenario. See the next section for an implementation.

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