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Optical Simulation

 

Areté’s core optics simulation technology is a radiative transfer code that provides accurate radiance calculations in an ocean environment. This code is organized into a series of modules that include radiative transfer in the ocean volume, through and off the ocean surface and through the atmosphere. The ocean technology includes wind generated waves, swells, three dimensional boat wakes, and whitecaps. The atmosphere technology includes mirage effects, polarization effects, and scattered cloud effects.

 

The above images show several visible band scenes generated by the radiative transfer technology. The image on the left is a sunset scene showing the scattering of the sun and atmosphere off the ocean surface. The image on the right shows a winter scene with clouds and whitecaps.

One major optics simulator developed by Areté is the Synthetic Ocean Scene Generator (SOSG). This tool provides a full space time simulation of visible and IR cameras viewing a time ocean scene. The scene can include any number of surface and airborne objects. The simulator models the motion of the objects and their dynamic interaction with the ocean surface. This tool combines the best of Areté technology with existing third party technology to provide a comprehensive ocean environment simulation tool. SOSG combines Areté radiative transfer and hydrodynamics code with ThermoAnalytics MuSes software for hardbody thermal signatures and with MODTRAN software for atmospheric radiances into a user friendly software tool that runs on a Windows workstation. The tool also interfaces with the COADS database to set simulation parameters relevant to any location on the earth at any time of the year. The overall architecture of the tool is shown in the figure below and is representative of the modular design of all of our simulation tools.

The tool generates radiance fields that compare favorably with actual ocean data. The figure below shows a simulated SOSG image that includes a mine floating in the water along with a screen capture of the GUI.

Another major set of tools based on our core optics technology is used to perform lidar simulations. In this case the propagation of the laser pulses from laser to receiver are modeled throughout the scene. The figure below shows an example of an Areté ladar simulation of an ocean scene consisting of a group of objects floating in the water. The simulation is shown in the upper left corner. Below the simulation is object detector output and to the right are the detections superimposed over a map.

In the coming year, Areté will be extending its optics simulation into the land based scenes in a program called the “Battlefield Environment Laser Radar Modeling Tool.” In this program Areté is developing an extensible, user-friendly modeling and simulation tool for performance evaluation of ladar systems operating in a battlefield environment. This tool will be based on a unique software architecture that provides flexible model fidelity choices to the user. This capability will allow user-selectable control of system models to provide the desired balance between model fidelity and processing speed. Thus, the software will support a range of processing activities, from quick-look analyses to high fidelity simulations, all in one package. The modular, extensible architecture will provide a mechanism for future expansion of capability.

The software tool will be a standalone application running on standard PC platforms. It will feature realistic models of battlefield obscurants and clutter such as fog, rain, smoke, and foliage. It will also feature an implementation architecture that takes advantage of platform-optimized vector and image processing libraries operating on standard CPUs and graphics processors. As a consequence, the user will have access to useful physical models in a package optimized for processing speed.

The above image shows a cartoon of the type of scene the Battlefield Environment Laser Radar Modeling Tool will simulate.