This is a real camera parameter:
const originExtrinsic = [0.9994466143126584, 0.033033376071303994, 0.003906559137689193, 0.20487898588180542, 0.0025198193977806005, 0.0419178508124942, 0.9991178830816032, 0.0013696063542738557, 0.033167991334523576, 0.9985748293686324, 0.04181141593201179, 0.10943480581045151, 0, 0, 0, 1]
const originIntrinsic = [1.2100629810000000e+03, 0.0, 1.0224299030000000e+03, 0.0,1.2058507139999999e+03, 7.9254164400000002e+02, 0.0, 0.0, 1.0]
the real camera photo size: width(2048px), height(1536px)
I transform them into internal parameter matrix and external parameter matrix
const extrinsic = new Matrix4()
extrinsic.set(originExtrinsic[0], originExtrinsic[1], originExtrinsic[2], originExtrinsic[3], originExtrinsic[4], originExtrinsic[5], originExtrinsic[6], originExtrinsic[7], originExtrinsic[8], originExtrinsic[9], originExtrinsic[10], originExtrinsic[11], originExtrinsic[12], originExtrinsic[13], originExtrinsic[14], originExtrinsic[15])
const intrinsic = new Matrix3()
intrinsic.set(originIntrinsic[0], originIntrinsic[1], originIntrinsic[2], originIntrinsic[3], originIntrinsic[4], originIntrinsic[5], originIntrinsic[6], originIntrinsic[7], originIntrinsic[8])
projection matrix:
const resMatrix4 = new Matrix4().setFromMatrix3(intrinsic).multiply(extrinsic)
Suppose there is a point coordinate in 3D space.
const myPoint = new Vector3(x,y,z)
Now, I have 3 questions:

How to derive a PerspectiveCamera based on existing conditions (extrinsic, intrinsic, resMatrix4) ?

How can I tell if myPoint appears in the real camera photo?
//if i know the perspectiveCamera const frustum = new Frustum() frustum.setFromProjectionMatrix(perspectiveCamera.projectionMatrix) // right? frustum.containsPoint(myPoint)

How to judge the position of myPoint in the real camera photo ?
//Is the code below correct? const position = myPoint.applyMatrix4(resMatrix4) const s = 1 / position.z position.set(position.x * s, position.y * s, 1) //position.x and position.y is the coordinate of point on the real camera photo ?