視覺障礙者占了台灣總人口的0.24%，是需要大家關注和幫忙的弱勢族群，而視障者最常碰到的就是導航問題，即獨自前往目的地的能力。視障者導航的相關文獻很多，也各有各的優缺點，本論文提出一個以電腦視覺技術為基礎的導航方法，利用顏色資訊配合擴增實境的編碼標籤(marker)，設計出一種彩色標籤，可以擺放在環境中，視障者只需使用智慧型手機的鏡頭來搜尋，手機便會找出環境中的標籤並發出回饋給視障者。數個標籤可以在環境中建構出路徑資訊，並儲存在資料庫中，當視障者輸入其目的地時，手機便比對環境中的標籤和資料庫中的標籤，將視障者沿著路徑導引至目的地。彩色標籤修改自擴增實境經常使用的黑白標籤，為了能穩定的在影像中找出顏色特徵，本論文使用了YCbCr和HSV兩種色彩空間的資訊來將影像二值化，以取出標籤的顏色區域。接著在二值化影像中尋找輪廓，檢查每個輪廓是否符合標籤的條件，並對符合條件的輪廓進行解碼以得到編碼的資訊，最後將編碼資訊轉換成導航資訊並發出回饋給使用者。實驗結果顯示，本論文提出的color marker可在室內和室外環境中使用，並能夠正確的將使用者引導至目的地，可見這個架構對於視障者導航的應用來說是相當有幫助的。Visually impaired people occupy 0.24% of the total population in Taiwan, they are the minority people who need to be looked after. The major challenge encountered by them is that of way finding, i.e., the ability of a person to find his way to a destination. There are a lot of literatures about way finding for visually impaired people, they all have pros and cons comparing with each other. In this thesis, a computer vision based algorithm is proposed, using the color information and the marker encoding method used in Augmented Reality, we design these color markers which can be placed in the environment. In practice, users used a smartphone to find the marker, and the phone will send a feedback to the users. A route can be built by several markers and saved in the database, when a user input his destination to the phone, it will conduct matching between the markers from the environment and the markers from the database so as to guide the user to their destination.The color markers are the modification of the binary markers which are commonly used in Augmented Reality. To get the color pattern from the image stably, we use the information from YCbCr and HSV color spaces to get marker’s color region in the image. Then, we try to find contours in the binary image. For each contour, we check if it fit the requirement for the marker. If it does, we decode it to generate the encoded message. Finally, the encoded message is translated to way finding information and feedbacks are sent to the users.Experimental results show that our color marker can be used in indoor and outdoor environments and can guide the users successfully to their destination. It reveals the validity and feasibility of the system in way finding for visually impaired people.
