即時的區域性立體視覺比對演算法分析與設計

Abstract

立體視覺廣泛的運用在許多領域，例如自走機器人、自動追蹤的攝影機、甚至於立體電視。由於許多的應用需要即時的立體視覺系統，因此需要設計一個能滿足高運算以及高頻寬的積體電路。 本篇研究提出了一個適合硬體設計的演算法，係基於適應性權重的計算(Adaptive Weight Generation)演算法結合微型普查(Mini-Census)的比對方式、兩次聚合(Two-Pass Aggregation)以及量子化指數曼哈頓距離(Quantized Manhattan Color Distance)等技巧。微型普查可以減少運算量，從原來的一個視窗的運算變成只有六個點運算。除此之外，他還加強了原本演算法中對於光線所造成的問題。兩階段資料匯集和量子化指數曼哈頓距離分別減少了88.7%和64.2%的運算複雜度。相較於原本的權重產生函式，量子化指數曼哈頓距離可以被實現成查表的硬體電路。 最後在聯華電子90奈米製程下，提出的設計可以在100MHz的工作時脈下達到每秒計算43張CIF畫面大小及64個階層的深度估測。晶片總共需要562,642個邏輯閘，以及21.3K的晶片記憶體。

Stereo matching has been widely used in many fields, such as automatic robots, auto-tracking system, and even the 3D-TV. With these real time application demands, VLSI implementation becomes necessary to fulfill the high complexity and high bandwidth requirements of stereo matching algorithms. In this thesis, we propose a hardware friendly algorithm, based on adaptive support weight (ADSW), with mini-census, two-pass aggregation, and quantized exponential Manhattan distance techniques. The mini-census reduces the computation complexity from a matching block to only 6 points. Besides, it also improves the capability of ADSW to deal with the radiometric problem. The two-pass aggregation and the quantized Manhattan color distance reduce about 88.7% and 64.2% computation of the cost aggregation respectively. Comparing to the original weight generation function, the quantized Manhattan color distance can be easily implemented by a table based circuit. The final design implemented by UMC 90nm CMOS technology can achieve 43 frames per second and 64 disparities with CIF image size under 100MHz clock rate. The chip consumes totally 562,642 K gate counts and 21.3K Bytes internal memory.