Study On Constructing Log Digital Outline By Through-type Scanning

The purpose of study is to explore a digital scanning system which could precisely scan the real outline of log. In this study, the line-shape laser is selected to serve as marking equipment, adopting the way of through-type scanning to obtain the real outline of cross section of log, on the base of these above, we reconstruct the 3D digital outline of log. There are four steps to obtain real outline of log cross section in random location at the ordinate axis direction: Camera Calibration, Image Restoring, Image Composition and Edge Extraction. When the log is moved forward, the equipment work continuously, at the same time scanning data information is stored in computer. Therefore the scanning efficiency is relatively high, and not restricted by length of log.The whole system is made up of hardware system and software system, the former can be divided into image acquisition system and equipment installation system, the latter can be divided into image grabbing, image processing and 3D display.The conclusions of study are listed as follows:1. CCD camera and image grabbing card are selected as image acquisition equipment, line shape laser as marking equipment, to construct the whole system of through-type scanning; Experimental results prove that when log diameter is confined between 200mm and 400mm, the precisely real outline of log cross section is achieved.2. Interference of natural daylight is suppressed by adopting line shape laser as marking equipment under dark environment. Experimental results prove the laser can reflect the real outline of log cross section and distinguish from background.3. Calibrating the system to get the relation between distance on image and real distance. Calculating based on the relation to find the real dimension of log.4. The system program could achieve log outline digital processing, displaying the feature of log outline on screen and changing the viewing angle; Experimental results prove that the 3D digital outline could precisely present the log feature of knots, cracks etc.