In this paper we introduce a software tool for image based computer simulation of an underwater gated viewing system. This development is helpful as a tool for the discussion of a possible engagement of a gated viewing camera for underwater imagery. We show the modular structure of implemented input parameter sets for camera, laser and environment description and application examples of the software tool. The whole simulation includes the scene illumination through a laser pulse with its energy pulse form and length as well as the propagation of the light through the open water taking into account complex optical properties of the environment. The scene is modeled as a geometric shape with diverse reflective areas and optical surface properties submerged in the open water. The software is based on a camera model including image degradation due to diffraction, lens transmission, detector efficiency and image enhancement by digital signal processing. We will show simulation results on some example configurations. Finally we will discuss the limits of our method and give an outlook to future development.
The Triangle Orientation Discrimination (TOD) is one of several methods to characterize electro-optical system performance. It is conducted by presenting an equilateral triangle pointing either up, down, right or left, to an observer who is forced to judge the direction. Based from the probability on the correctness of the answers in dependence of the size of the triangle, the quality of the system can be assessed. In order to gain experience with this method it was applied here to test Fraunhofer IOSBs new equipment for perception experiments.
An experiment with four observers, ten contrast levels and six triangle sizes was conducted. Its results were analysed for observer performance versus time, illumination conditions and variations in the TOD-curve. Furthermore, different approaches on analysing the data were compared.
The outcome showed the observers performance variation on different days to be statistically insignificant. In addition, the illumination conditions had no statistically significant influence on the result. Interestingly a larger difference was found between the observers. Although they had normal or corrected to normal eyesight, different visual acuity is the only explanation for the differences. This leads to the necessity to check observers of perception experiments more closely. The different approaches to curve fitting also gave variations, which would result in different ranges when applied in camera assessment. Here a standardization seems necessary when the method is applied in analytical models for imaging systems.
There is a large diversity of phase functions for the computer simulation of light under water. Some papers look at the influence of these phase functions on the results of computer simulations of the remote sensing reflectance. We study the influence of these phase functions on the computer simulation of the resulting image of a target illuminated by a laser. For these simulations we are only interested in those parts of the light that reach the camera position. Therefor we investigate the influence of the phase function on the image. We use a Monte Carlo Simulator with several Fournier-Forand, Henyey-Greenstein phase functions. The resulting signals at the receiver of these simulations are compared to a simulation with a Petzold function that is based on measurements of the phase function.
Conference Committee Involvement (1)
Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIX