Kinect - clamp detection range

Hi
Does anyone know of a way to clamp maximum detection range when using a Kinect device?

I want to limit the maximum distance at which a person is detected.
Pretty sure this is exposed in the Kinect SDK but don’t see anything in the Kinect TOP.

In shader land, I move pixels based on a z threshold

uniform float uDepthThreshold;

void main() {
vec4 pos = texture(sTD2DInputs[0], vUV.st);

if (pos.z < uDepthThreshold) {
    //move the point somewhere not visible by the camera
   pos.xyz = vec3(-10000);
}

// output pos
fragColor = pos;
}