多角度人臉辨識電腦視覺應用裡相當挑戰性的主題。本論文主要探討兩大情景，一是常見的對每位註冊者使用一張正面人臉影像，測試影像為註冊者不同視角之影像。另一則採用正面RGB-D影像於註冊，測試影像和前者相同為不同視角之RGB影像。第二種情景模擬僅註冊階段具備RGB-D攝影機，並可對所有不含深度資訊之RGB影像進行人臉辨識。本論文對第一情景提出兩種方法架構：基於全人臉與局部人臉區域的方法。前者為一人臉重建方法之延伸，透過採用不同數目之人臉特徵、使用多個參考模型來改善其效能。後者著重於對局部人臉區域進行重建，人臉區域是根據角度不變性的特徵所定義，辨識考慮各個區域在不同視角下的比對。此一基於局部人臉區域，進行三維重建用於多角度人臉辨識，在過去的文獻當中相當少被探討。在第二種基於RGB-D影像的情景中，儘管與第一種情景在辨識部分存在相似之處，其創新之部分在於處理深度讀取過程所產生之取樣雜訊。本論文提出對失真深度表面平滑之方法，此方法可大幅改善辨識效能。所有提出之方法皆評估於現有資料庫上，其效能與現有之方法相比不相上下。

Face recognition across pose is a challenging problem in computer vision. Two scenarios are considered in this thesis. One is the common setup with one single frontal facial image of each subject in the gallery set and the images of other poses in the probe set. The other considers a RGB-D image of the frontal face for each subject in the gallery, but the probe set is the same as in the previous case that only contains RGB images of other poses. The second scenario simulates the case that RGB-D camera can be available for user registration only and recognition can be performed on regular RGB images without the depth channel. Two approaches are proposed for handling the first scenario, one is holistic and the other is component-based. The former is extended from a face reconstruction approach and improved with different sets of landmarks for alignment and multiple reference models considered in the reconstruction phase. The latter focuses on the reconstruction of facial components obtained by the pose-invariant landmarks, and the recognition with different components considered at different poses. Such a component-based reconstruction for handling cross-pose recognition is rarely seen in the literature. Although the approach for handling the second scenario, i.e., the RGB-D based recognition, is partially similar to the approach for handling the first scenario, the novelty is on the handling of the depth readings corrupted by quantization noise, which are often encountered when the face is not close enough to the RGB-D camera at registration. An approach is proposed to resurface the corrupted depth map and substantially improve the recognition performance. All of the proposed approaches are evaluated on benchmark databases and proven comparable to state-of-the-art approaches.

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