Key Facts
- Type lines can vary in length and are crucial for enclosing fingerprint patterns.
- Bifurcations involve a single line splitting into two or more branches.
- Divergences occur when two parallel lines spread apart.
- Ridges can bifurcate but not diverge, and only diverging lines can be considered type lines.
- Fingerprint readers may fail to recognize quality due to their reliance on bifurcations in ridge mapping.
Type lines, which enclose fingerprint patterns, can be very short, or long.
Another very important characteristic of type lines is that they sometimes contain bifurcations or divergencies.
A bifurcation is the forking or dividing of one line into 2 or more branches, while a divergence is the spreading apart of 2 lines which have been running parallel or nearly parallel.
A single ridge may bifurcate, but not diverge. The 2 forks of a bifurcation are not type lines, unless the lines run parallel after bifurcating and then diverge.
The opposite of bifurcation is coalescence or fusion. This sometimes happens in older applicants, where previously separate ridges converge to form a single continuous ridge.
Often times, clients will have friction ridges that are pronounced and provide good electronic images, yet biometric fingerprint readers at the local level fail to indicate a “passing” fingerprint quality mark.
This is because the readers are trained to identify bifurcations as part of their mapping of ridges.
We will address the science of fingerprint identification in later posts.
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