Image Capture and Mosaicing for Sediment Tube Trap

• Main Authors: Shih-jung Li, 李士榮
• Other Authors: Chau-Chang Wang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/49849401557408294437

碩士 === 國立中山大學 === 海下科技暨應用海洋物理研究所 === 101 === The changing process of suspension particles in water can be documented by collecting them in a sediment trap. Sinking particles are stored in a transparent tube similar to the conventional coring tubes. After recovering the sediment trap sample, it is necessary to take a series of photos to preserve the appearance of original layer structure. The sediment sample in the tube tends to degrade rapidly in room temperature. As a result, the image acquisition needs to be completed as soon as possible. Limited by the optics of the camera, a single high resolution image to preserve the sediment texture can only be done by mosaicing a series of close shots. Therefore, we need to have a moving table which keeps a fixed distance between the camera and the tube while moving smoothly along the main axis of the tube. Sediment layered structure can be easily disturbed by vibration. So the core tube needs to maintain vertical and still while taking the image. The light source is mounted on both sides of the tube,to provide high-speed shutter required.By using Area of Interest (AOI) mode of the camera, only a small linear area of the image is taken for mosaic. This method reduces the acquisition time and mosiacing time significant. Mosaicing technology lies in the image feature extraction and feature matching success rate of particle images in the settlement of this study Is more than the granular and lateral characteristics of the image, so the use of Harris Corner detection methods, the use of the characteristics of the corner feature extraction, and image feature point of the overlap region search. Application of the NCC (on Normalized Cross Correlation) to calculate the correlation coefficient of the highest match points to get preliminary estimates suggest that more accurate displacement, and then use the matching feature points out of the box features range during NCC''s calculations do fine-tuning operations to obtain the correct displacement of the stitching, to the automated core image capture mosaic technology.