The Application Of Digital Close-range Photogrammetry In Measureing The Growth Of Plants

Ordinary digital camera is widely used in the field of Close-range photogrammetry, because of its low prices, portability and easy operation, the research of close-range obojects' 3D reconstruction by using ordinary digital camera is rapidly becoming a hotspot in the recent years. This paper applied the technique to help measure the growth of fascicular plants with stimulant test for the first time.In the experiment,we used an ordinary digital camera to get objects' images, 3D control field is then use to determine lens distortion of the digital camera. As this photogrammetric techniques and methods are based on ordinary digital images, it can be applied extensively in the measurement which requests only a moderate accuracy. Because it is difficult to find textures from the surface of fascicular plant, we used some easily manipulable color silk thread. We also desigs a portable control system to compute the orientation parameters. In order to improve the precision, we use bundle adjustment algorithms in the data processing and regard the value of the control points as the value.In this paper, we discuss the principles and methods of digital close-range photogrammetry. Besides, based on the characteristic of man-made textures, we integrate Ziplock snakes and the Ribbon snakes algorithms to improve traditional active sketh models in extracting the centre line of the man-made zonary texture from complicated background. Homonymous epipolar lines are used to obtain feature points from linear texture. From the above processes, we finaly reconstructe the 3D models of the sample plants in different growth stages, and calculate the corresponding volume increments of the sample plants.The results show that the sample plants' volume increments and growth data can be easily calculated through a number of image taken by ordinary digital camera without the need of tremendous field measure work. In addition, the calculated results can be easily output as figures and/or forms. Most importantly, this method does not damage the sample plant and its growth environment. It provide a new way for investigating the status of outdoor plants'growth.