how to get the custom projection matrix of UIImagePickerController 's camera

I use UIImagePickerController as camera. Now I want to integrate with ogre 3d render to make an ar application. Does someone know how to get the custom projection matrix of UIImagePickerController.

I convert cameracontroller.cameraviewtransform to a matrix. and the view matrix I just convert 2dar affinetransform to transf开发者_JS百科orm3d.

but it doesn't work.

Worse comes to worst, you can generate the projection transform from what you know about the camera, which is primarily just the FOV angle. Things like the orientation and location of the camera in an AR application are simply offsets from whatever your defaults are, and this data can be retrieved from the gyro and accelerometer.