How to extract camera parameters from Projection matrix

Question

I have a Perspective Camera with a certain projection matrix ,I just want to extract the fow , near plane and far plane from it. I know there is a function in Three.js :

.updateProjectionMatrix()

it creates a projection matrix based on parameters listed above, basically i want the reverse process.

Possible duplicate: https://stackoverflow.com/questions/46182845/field-of-view-aspect-ratio-view-matrix-from-projection-matrix-hmd-ost-calib — WestLangley, Jun 03 '19 at 14:45
From what I read he does not say how to calculate the near and far plane @WestLangley — binaryRat, Jun 03 '19 at 15:10

score 5 · Accepted Answer · answered Jun 04 '19 at 07:22

5

I solved with this 3 formulas :

fov = 2 * atan(1/camera.projectionMatrix.elements[5]) * 180 / PI;

near = camera.projectionMatrix.elements[14] / (camera.projectionMatrix.elements[10] - 1.0);

far = camera.projectionMatrix.elements[14] / (camera.projectionMatrix.elements[10] + 1.0);

Sources :

3D Projection

Decompose the OpenGL projection matrix

Field of view + Aspect Ratio + View Matrix from Projection Matrix

answered Jun 04 '19 at 07:22

binaryRat

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Do you happen to know if there's anything else to extract from the matrix to completely 'clone' the camera behavior? I did setup a [JsFiddle](https://jsfiddle.net/jurito/013x78n4/19/) with an example of what i want to achieve. Basically you click on the scene and it switches camera to another one created with the extracted properties, but as you see it's not working as expected.. – jurito Dec 19 '21 at 15:46

How to extract camera parameters from Projection matrix

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