Development of Digital Surface Model and Feature Extraction by Integrating Laser Scanner and Ccd Sensor with Imu

Three dimension data are in great demand for the various applications such as 3D GIS, navigation, digital archive, simulation, computer games, and so on. In order to represent space in details, it is indispensable to acquire 3D shape and texture together. However, there still lacks a reliable, quick, and handy method of acquiring three dimension data at higher resolution. In this research, we propose a combination of a digital camera and a small (cheap) laser scanner with inexpensive IMU (Inertial Measurement Unit) for unmanned air vehicles. 3D shape is acquired by laser scanner as point cloud data, and texture is acquired by CCD sensor from the same platform simultaneously. Positioning data is acquired by GPS (Global Positioning System) and IMU. All the sensors are synchronized with movement or attitude of the platform. In this paper, a method of integrating all the sensors is focused. All the sensors are tightly fixed on the platform to establish rigorous geometric relationships. Calibration of laser scanner and CCD camera is conducted to know relative position and attitude of each sensor against GPS and IMU. Through Kalman filter, an optimal estimate of the sensor position and attitude is estimated from GPS and IMU. Bundle block adjustment is conducted using continuous CCD images. The result of bundle block adjustment aids Kalman filter by initialization of position and attitude. Using this measurement system, a procedure for automated construction of digital surface model is developed using these sensors. This paper proposes a new method of rendering objects with rich shape and detailed texture. Sensor position and attitude for mapping are basically acquired by GPS/IMU and their errors are complemented by digital camera images using tie point. In case of real time mapping, colored point cloud model is produced as a quick view. Feature extraction is conducted by range data and image data. Geometric shape which is acquired by leaser scanner represent features. Texture information, which is acquired by digital camera, details those features. That is, more detailed extraction is possible using both 3D shapes and colors. It is possible to extract not only man-made object but also natural object such as people and vegetation. * Corresponding author. Masahiko Nagai Tel: +81-3-5452-6417 [email protected]