It is necessary to examine EERS1-SAR imaging mechanism of the sea surface for the ocean wave observation by using EERS1-SAR images. In this study, we performed a numerical simulation to examine EERS1-SAR imaging mechanism of ocean waves. In the numerical simulation, a two-dimensional wavenumber spectrum was calculated from the benchmark directional wave spectrum by a quasi linear theory. In addition, inversely to estimate the directional wave spectrum from waves visualized by the EERS1-SAR, we made a sequential analysis using the quasi-linear theory to calculate a two-dimensional wavenumber spectrum of a SAR image from the directional wave spectrum observed by wave gage array, and verified the validity of the analysis and clarified the problems of the inverse analysis that estimated the directional wave spectrum from EERS1-SAR images. It is clarified from the sequential analysis using the quasi-linear theory that the directional wave spectrum can be estimated from the SAR image.
This paper proposes Triangular-Prism Model Method (TPMM) for 3-D space description. TPM, considered as an extension of TIN model, consists of triangular prisms and each top triangle is surface of the ground, buildings, and other objects on the ground. Vertical walls also can be expressed with side face of prisms. TPMM simplifies visibility analysis between elements of surface model. Visibility among a group of triangular prisms can be related with visibility of a group of 2-D triangles that are projection of the prisms onto 2-D space. This paper introduces visibility sorting, where triangular prisms are sorted according to visibility from a viewpoint. The visibility sorting has been applied to true orthoimage processing where occlusions by buildings are essential. Tests with 30 aerial images of Shinjuku area resulted that occluded area around building was extracted in each true orthoimage. True orthoimages can be synthesized into one composite true orthoimage where occluded areas of one image are compensated with other true orthoimages.
A convenient 3D measurement using amateur digital camera is enormously expected from various fields according to appearance of the high resolution amateur digital cameras since pixel numbers of amateur digital cameras are amazingly increasing by modern semiconductor and digital technology. In these circumstances, software for low-cost digital photogrammetry“3DiVision”was designed to perform convenient 3D measurement using amateur digital cameras. However, there are problems for efficient digital photogrammetry using amateur digital camera. These problems are distance measurement and preliminary interior orientation, and these restrictions should be removed for ideal convenient photogrammetry. With this objective, composite photogrammetric device was developed by the authors consisting of 5 parts : mirrors, an amateur digital camera, a laser range finder, a personal computer and a monitor. The most remarkable point of this system is its ability to calculate orientation parameters without scale distance or GCP in an object field. This paper describes the composite photogrammetric device and its performance evaluation.