Biometrics 简明教程

Multimodal Biometric Systems

迄今为止我们讨论的所有生物识别系统都是单模态的，它们采用单一信息来源进行验证。顾名思义，多模态生物识别系统可以接受两个或更多生物识别输入的信息。

All the biometric systems we discussed till now were unimodal, which take single source of information for authentication. As the name depicts, multimodal biometric systems work on accepting information from two or more biometric inputs.

多模态生物识别系统增加了系统从用户处获取的输入信息范围和种类，用于验证信息。

A multimodal biometric system increases the scope and variety of input information the system takes from the users for authentication.

Why Multimodal Biometrics is Required?

单模态系统需要应对各种挑战，例如缺乏隐秘性、样本的非普遍性、用户在使用系统时的舒适度和自由程度、存储数据的欺骗攻击等。

The unimodal systems have to deal with various challenges such as lack of secrecy, non-universality of samples, extent of user’s comfort and freedom while dealing with the system, spoofing attacks on stored data, etc.

采用多模态生物识别系统可以解决其中一些挑战。

Some of these challenges can be addressed by employing a multimodal biometric system.

需要它还有许多其他原因，例如 -

There are several more reasons for its requirement, such as −

  1. Availability of multiple traits makes the multimodal system more reliable.

  2. A multimodal biometric system increases security and secrecy of user data.

  3. A multimodal biometric system conducts fusion strategies to combine decisions from each subsystem and then comes up with a conclusion. This makes a multimodal system more accurate.

  4. If any of the identifiers fail to work for known or unknown reasons, the system still can provide security by employing the other identifier.

  5. Multimodal systems can provide knowledge about “liveliness” of the sample being entered by applying liveliness detection techniques. This makes them capable to detect and handle spoofing.

Working of Multimodal Biometric System

多模式生物识别系统具有单模式系统所具有的所有常规模块 -

Multimodal biometric system has all the conventional modules a unimodal system has −

  1. Capturing module

  2. Feature extraction module

  3. Comparison module

  4. Decision making module

此外，它还具有融合技术，以整合来自两个不同认证系统的的信息。融合可以在以下任何级别完成 -

In addition, it has a fusion technique to integrate the information from two different authentication systems. The fusion can be done at any of the following levels −

  1. During feature extraction.

  2. During comparison of live samples with stored biometric templates.

  3. During decision making.

multimodal biometric system

在初始阶段集成或融合信息的多分系统被认为比在后期集成信息的系统更有效。原因很明显，早期阶段比比较模块的匹配分数包含更准确的信息。

The multimodal biometric systems that integrate or fuse the information at initial stage are considered to be more effective than the systems those integrate the information at the later stages. The obvious reason to this is, the early stage contains more accurate information than the matching scores of the comparison modules.

Fusion Scenarios in Multimodal Biometric System

在多分身生物特征识别系统中，特征和组件的数量可能会有所不同。它们可能是以下形式 -

Within a multimodal biometric system, there can be variety in number of traits and components. They can be as follows −

  1. Single biometric trait, multiple sensors.

  2. Single biometric trait, multiple classifiers (say, minutiae-based matcher and texture-based matcher).

  3. Single biometric trait, multiple units (say, multiple fingers).

  4. Multiple biometric traits of an individual (say, iris, fingerprint, etc.).

然后对这些特质进行操作以确认用户的身份。

These traits are then operated upon to confirm user’s identity.

Design Issues with Multimodal Biometric Systems

在设计多分身生物特征识别系统时，您需要考虑许多因素 -

You need to consider a number of factors while designing a multimodal biometric system −

  1. Level of security you need to bring in.

  2. The number of users who will use the system.

  3. Types of biometric traits you need to acquire.

  4. The number of biometric traits from the users.

  5. The level at which multiple biometric traits need integration.

  6. The technique to be adopted to integrate the information.

  7. The trade-off between development cost versus system performance.