CBP Biometric Fusion and Multimodal Systems 3

Question 1

Bayesian fusion in multimodal biometrics computes the final decision by:

Accepted Answer

Combining likelihood ratios using Bayes' theorem to estimate posterior probability of identity

Answer

Bayesian fusion uses Bayes' theorem to combine evidence from multiple matchers by computing the posterior probability of a claimed identity given all observed match scores.

Question 2

How does multimodal biometric fusion help address the Failure to Enroll (FTE) problem?

Accepted Answer

It allows enrollment to succeed even if one modality fails, using remaining modalities

Answer

Multimodal systems can enroll users who fail in one modality (e.g., poor-quality fingerprints) by relying on other available modalities, reducing overall system FTE rate.

Question 3

In a weighted sum fusion rule, weights are typically assigned based on:

Accepted Answer

The Equal Error Rate (EER) or other performance measures of each individual matcher

Answer

Weights in weighted sum fusion are typically derived from the performance characteristics of each matcher, such as its EER, so that more accurate matchers have greater influence on the final score.

Question 4

Anti-spoofing (liveness detection) in a multimodal system is best described as:

Accepted Answer

An additional layer that verifies sample authenticity before or after fusion

Answer

Liveness detection operates independently of fusion strategy, verifying that each presented sample comes from a live person before or after the fusion stage to prevent presentation attacks.

Question 5

What is the concept of 'adaptive fusion' in multimodal biometric systems?

Accepted Answer

Dynamically adjusting fusion weights or strategy based on real-time signal quality or context

Answer

Adaptive fusion dynamically modifies the fusion parameters (e.g., weights, thresholds) based on factors such as sample quality scores or environmental conditions to optimize system performance.

(CBP) Certified Biometrics Professional Practice Test

(CBP) Certified Biometrics Professional Practice Test

CBP Biometric Fusion and Multimodal Systems 3