Sensor modelling for aerial mobile mapping with Three-line Scanner (TLS) imagery

extraction. ABSTRACT: This paper describes the sensor modeling and the photogrammetric triangulation procedure for the TLS (Three-Line-Scanner) system. This system is a new airborne digital sensor developed by Starlabo, Tokyo, jointly with the Institute of Industrial Science, University of Tokyo. It utilizes the Three-Line-Scanner principle to capture digital image triplets in along-strip mode. The imaging system contains three times (red, green and blue channels) three parallel one-dimensional CCD arrays, with 10200 pixels of 7mm each. They produce seamless high-resolution images (3.5 – 5.8 cm footprint on the ground at 300 – 500 m height) with three viewing directions (forward, nadir and backward). In order to get precise attitude data and high quality image data from an aerial platform, a high quality stabilizer stabilizes the camera and outputs attitude data at 500 Hz. A Trimble MS750 serves as Rover GPS and collects L1/L2 kinematic data at 5 Hz and another Trimble MS750 serves as Base GPS on the ground. The position and attitude elements measured by the on-board GPS/INS do not refer to the perspective center of the imaging camera. Additionally, there is a boresight misalignment between the axes of the INS and the camera. These translational and rotational offsets have been taken into account in our sensor model and combined triangulation procedures. In our experiments, the following 3 trajectory model are evaluated: (a) Direct georeferencing with stochastic exterior orientations (DGR), (b) Piecewise Polynomials with kinematic model up to second order and stochastic first and second order constraints (PPM) and (c) Lagrange Polynomials with variable orientation fixes (LIM)