Development of Software to create a Rectified Image of an Inclined Plane
Ryuji MATSUOKA
Tokai University Research & Information Center
2-28-4 Tomigaya, Shibuya-ku, Tokyo 151-0063, JAPAN
Phone: +81-3-3481-0611, Fax: +81-3-3481-0610
E-mail: ryuji@yoyogi.ycc.u-tokai.ac.jp
Naoki SHIRAI
Department of Research and Development, Kokusai Kogyo Co., Ltd.
2 Rokuban-cho, Chiyoda-ku, Tokyo 102-0085, JAPAN
Phone: +81-3-3288-5921, Fax: +81-3-3262-6150
E-mail: nshirai@kkc.co.jp
Keywords
image rectification, digital camera, analytical photogrammetry
Abstract
A piece of software to create a rectified image of an inclined plane for geological
survey at a construction site has been developed. The major advantage of our software is that it is easy for a nonprofessional to create a rectified image with sufficient quality.
Digital camera images of an inclined plane are utilized for geological survey at a construction site. A target slope is too large to be covered by one image with sufficient spatial resolution. Not less than several, usually more than ten digital images taken for a target slope should be rectified and connected each other to become an image covering the whole of the target slope. At present each acquired image is manually deformed one by one using a piece of photo-retouch software in PC, and deformed images are also manually connected. This work takes time and quality of the produced image depending on skill of an operator is unsatisfactory in some cases.
Accordingly, we decided to develop a piece of software to create a rectified image covering the whole of an inclined plane in a short time and sufficient quality without ground survey of control points. Our software is based on analytical photogrammetry and image processing technologies, and it is designed for an amateur such as a geological engineer without photogrammetric or image processing know-how to operate it easily after short-period training.
1. Introduction
Photographs of an inclined plane have been utilized for geological survey at a site of a massive scale construction such as dam and highway construction. A lot of analog photographs used to be taken at a construction site. As performance of a digital camera becomes better and its price becomes lower in recent years, digital camera images are becoming major at a construction site.
A digital camera image has several advantages; one is that its quality can be examined immediately after exposure without development, and another is that image data can be transferred directly into a computer. However, a major weak point of a digital camera image is its lower spatial resolution. A target inclined plane is too large to be covered by one image with sufficient spatial resolution. Not less than several, usually more than ten digital images are taken for a target slope. They should be rectified and connected each other to become an image covering the whole of the target slope.
Figure 1 shows a pair of adjacent images of an inclined plane. Each image has a pair of scales on both left and right sides. Though a pair of scales was laid in parallel on the slope, a pair of scales on the image looks not in parallel because a photographer faced obliquely to the target plane. Figure 2 demonstrates a process of creating a rectified image. Each image is deformed and connected each other to become an image covering the whole of the target slope.
At present each acquired image is manually deformed one by one using a piece of photo-retouch software in PC, and deformed images are also manually connected. This work takes time and quality of the produced image depending on skill of an operator is unsatisfactory in some cases. Accordingly, we decided to develop a piece of software to create a rectified image covering the whole of an inclined plane in a short time with sufficient quality.
Figure 1 A pair of adjacent images of an inclined plane
