Digital fingerprints generated from coil brazing

A method for generating digital fingerprints from coil brazing, comprising:

• receiving video footage from a camera configured to record video of evaporator coil slabs after they exit an automated coil brazer, the footage comprising a plurality of evaporator coil slabs;
• converting the video footage to greyscale;
• isolating, from the greyscale footage:
• a first frame comprising an image of a first evaporator coil slab, the coil slab comprising a plurality of brazed tube junctions;
• a second frame comprising an image of a second evaporator coil slab, the coil slab comprising a plurality of brazed tube junctions;
• identifying, using a corner detection algorithm, a first plurality of feature points in the first frame and a second plurality of feature points in the second frame, the feature points comprising corners;
• determining that a first subset of feature points selected from the first plurality of feature points and a second subset of feature points selected from the second plurality of feature points are rotationally invariant, wherein a point is rotationally invariant if it remains identifiable in images of the slab taken from a different angle;
• applying a binary descriptor algorithm to the first subset of feature points to generate a first digital fingerprint comprising a binary feature vector for each point in the first subset of feature points;
• and
• applying the binary descriptor algorithm to the second subset of feature points to generate a second digital fingerprint comprising a binary feature vector for each point in the second subset of feature points.

A computer program comprising executable instructions stored in a non-transitory computer readable medium that when executed by a hardware processor cause the hardware processor to:

• convert video footage, received from a camera configured to record video of evaporator coil slabs after they exit an automated coil brazer, to greyscale;
• isolate, from the greyscale video footage:
• a first frame comprising an image of a first evaporator coil slab, the coil slab comprising a plurality of brazed tube junctions;
• a second frame comprising an image of a second evaporator coil slab, the coil slab comprising a plurality of brazed tube junctions;
• identify a first plurality of feature points in the first frame and a second plurality of feature points in the second frame, the feature points comprising corners;
• determine that a first subset of feature points selected from the first plurality of feature points and a second subset of feature points selected from the second plurality of feature points are rotationally invariant, wherein a point is rotationally invariant if it remains identifiable in images of the slab taken from a different angle;
• generate a first digital fingerprint comprising a binary feature vector for each point in the first subset of feature points;
• and
• generate a second digital fingerprint comprising a binary feature vector for each point in the second subset of feature points.