The External Camera feature is a part of the Vuforia Engine Driver Framework. The External Camera defines all the specifics required for Vuforia Engine to access external image sources. Up until the introduction of the External Camera feature, Vuforia Engine has handled the acquisition of the camera frame data internally. With External Camera, developers are able to define how Vuforia Engine acquires frame data. The External Camera must implement several APIs which the Vuforia Engine uses to access the external system. For more information on how to create your own External Camera, refer to Creating a Custom Driver.
It’s important to note that only vision-based features are currently supported through the External Camera feature. This is all Vuforia features, however DeviceTracker will work only using
FUSION_PROVIDER_VUFORIA_VISION_ONLY. This will make Ground Plane cease to work and ModelTargets will operate in a less robust manner."
Vuforia Engine provides two Samples which demonstrate how to access image data from external systems. The File Driver loads a sequence of images from device storage. The UVC Camera Driver allows developers to access USB cameras from within Android.