fromScene( scene, sigma = 0, near = 0.1, far = 100 ) {

    		_oldTarget = this._renderer.getRenderTarget();
    		const cubeUVRenderTarget = this._allocateTargets();

    		this._sceneToCubeUV( scene, near, far, cubeUVRenderTarget );
    		if ( sigma > 0 ) {

    			this._blur( cubeUVRenderTarget, 0, 0, sigma );

    		}

    		this._applyPMREM( cubeUVRenderTarget );
    		this._cleanup( cubeUVRenderTarget );

    		return cubeUVRenderTarget;

    	}
Generates a PMREM from a supplied Scene, which can be faster than using an
image if networking bandwidth is low. Optional sigma specifies a blur radius
in radians to be applied to the scene before PMREM generation. Optional near
and far planes ensure the scene is rendered in its entirety (the cubeCamera
is placed at the origin).