A processor system (200) processes image data from a camera (20) to render a virtual object in a 3D virtual environment and communicate via a network to a server system (300). A processor (220) obtains image data of the physical space from the camera and second data of a second device (30). The processor system sends the image data, the second data and a calibration command to the server system. In the server, a processing resource (320) processes the data according to the calibration command and sends calibration data indicative of a camera pose and a second pose of the second device. The processor generates 3D object data of the object by processing the image data based on the calibration data. The 3D object data is provided for rendering the virtual object in the 3D virtual environment. So, the processor is in control, while the calibration is executed by the server.