Extract a Volume of points from a PointCloud2 message

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Hi all, I'm trying to achieve something simple, yet I can't seem to find a way to do this. I have a PointCloud2 (as a .pcd file) and a bounding box defined in the same frame as the PointCloud2. I want to extract all the points that lie inside that bounding box and save them as a new .pcd file with the centroid of the box set as the origin of that point cloud.

A sample bounding box looks like this:

"bbox": {
            "position": {
                "position": {
                    "y": -24.204870224, 
                    "x": 23.0722198486, 
                    "z": -2.88637971878
                }, 
                "orientation": {
                    "y": -0.0256392564625, 
                    "x": 0.01510348171, 
                    "z": 0.704603254795, 
                    "w": 0.708977282047
                }
            }, 
            "size": {
                "y": 1.84718394279, 
                "x": 3.94384384155, 
                "z": 1.66313385963
            }
        }

So I have the position (which I want to be the origin of the new PointCloud), the size of the box, and also the orientation as a quaternion.

How can I do this? Any pointers to PCL tutorials would be helpful as well. Thank you!