DocumentVerificationOverlay is overlay for RecognizerRunnerFragment, best suited for combined recognizers because it manages the scanning of multiple document sides in the single-camera opening and guides the user through the scanning process.
Combined recognizers have the option to scan both front and the back side together with the extraction of the images of the document. Some combined recognizers support scanning of multiple document types, but only one document type can be scanned at a time.
List of the supported combined recognizers:
MRTD Combined - The
MrtdCombinedRecognizer scans Machine Readable Zone (MRZ) after scanning the full document image and face image (usually MRZ is on the back side and face image is on the front side of the document). Internally, it uses DocumentFaceRecognizer for obtaining full document image and face image as the first step and then MrtdRecognizer for scanning the MRZ.
USDL Combined - The
UsdlCombinedRecognizer scans PDF417 barcode from the back side of US / Canada driver's license after scanning the full document image and face image from the front side. Internally, it uses DocumentFaceRecognizer for obtaining full document image and face image as the first step and then UsdlRecognizer for scanning the PDF417 barcode.
- back side of Austrian ID after scanning the front side and combines data from both sides
- Austrian passport
- back side of new German ID after scanning the front side and combines data from both sides
- front side of old German ID
- German passport
This video tutorial describes how to use documentVerificationOverlay with UsdlCombinedRecognizer. In version 4.1 we discovered a small bug in our UI which was caused by the SuccessFrameGrabber. After captured complete frame, it didn't prompt the user to switch scanning to the back side, even if recognizer for the back side scanning is active.
Removing the FrameGrabber will result in not returning the full frame from the video stream but it will prompt a user to scan the back side.