We describe a new real-time multispectral dynamic scene simulation system in this paper. Based on the spectral
signatures, we model the multispectral flying targets for scene simulation and consider the atmospheric attenuation effect
to enhance the scene reality. A key-frame based pre-calculation rendering algorithm is also present to accelerate the
scene simulation speed. We also realize the multi-resolution multispectral backgrounds texture generation and real-time
loading. In our simulation system, users can interactively real-time change the scene wavebands and viewpoints to
observe the flying targets. Users can also play back the videos of the dynamic processes for further analysis after the
simulation. The average dynamic rendering speed of our scene simulation is larger than 80fps and the experiments show
the potential of our multispectral dynamic scene simulation system.
In this paper, we propose a new method to generate complex IR scene image directly from the corresponding visual scene image based on material thermal database. For the input visual scene image, we realize an interactive tool based on the combined method of global magic wand and intelligent scissors to segment the object areas in the scene. And the thermal attributes are assigned to each object area from the thermal database of materials. By adopting the scene infrared signature model based on infrared Physics and Heat Transfer, the surface temperature distribution of the scene are calculated and the corresponding grayscale of each area in IR image is determined by our transformation rule. We also propose a pixel-based RGB spacial similarity model to determine the mixture grayscales of residual area in the scene image. To realistically simulate the IR scene, we develop an IR imager blur model considering the effect of different resolving power of visual and thermal imagers, IR atmospheric noise and the modulation transfer function of thermal imager. Finally, IR scene images at different intervals under different weather conditions are generated. Compared with real IR scene images, our simulated results are quite satisfactory and effective.
Images of outdoor scenes captured in bad weather usually suffer from poor contrast. The reason is that the light reflected from the scene is attenuated by heavy aerosol particles' scattering. And the attenuation increases exponentially with the distances of each scene point from the sensor. In this paper, we propose a simple method to remove weather effects using only a single image. Our algorithm has three main steps. First, based on the exponential law, we propose a new primary model for de-weathering with only one parameter which is simple and easy to manipulate and then we prove its theoretic validity. Second, we bring forward two distance fields to estimate the whole depth information in the image for two different situations. And they are computed in an interactive way. Third, to overcome the defect of a single image which lacks the exact depth information, we propose an interactive post modifying algorithm to adjust the local restoration effect finely. The modifying algorithm is based on two piecewise functions controlled by two parameters. Our algorithm is suitable not only for gray level images but also for RGB color images. Compared with other methods, our method is robust and the results are quite satisfying.
Recently infrared signature simulation has been in a state of great interest. Although various models have been developed to generate synthetic image of infrared scenes, little work has been done to create high fidelity infrared image of bridge. In this paper a realistic model for infrared image synthesis of bridge based on its thermal energy transmission is proposed to generate the infrared image of bridge at different time. Our new IR image synthesis model of bridge accounts for meteorological, environmental, material and artificial factors. Then an energy equilibrium equation is built based on the principle of heat transfer and infrared physics. And a finite difference method is adopted to solve the equations. Finally we get the radiance distribution of target surface. To get high fidelity, the effect of atmosphere is added using LOWTRAN model. The value of attenuation is pre-computed and stored in our database. We also pre-generate infrared texture and depth attenuated image from visible image. Infrared images of bridge from different viewpoints at different time can be rendered. Our results of simulation show that the model is robust and feasible.
A new model for realistic IR image rendering of city buildings was proposed in this paper. Within the model, We first analyzed the main kinds of factors affecting the infrared characteristic of city buildings such as air temperature, relative humidity, wind speed, sun and sky radiations. Then we established an energy equation based on principle of energy equilibrium for the surface parts of city building scene and by adopting multi-layer infinite difference method and Gauss-Seidier’s iterative method, the surface temperatures of building scene under various conditions were acquired. To make the IR scene more realistic, we proposed a new method to obtain IR texture from its corresponding visible image based on the spectral correlation and the thermal attribute of the classified materials in scene. Using Ray tracing to determine IR shadow area and render the IR scene of city building with high-reality. To simulate the attenuated and blurred effect of atmosphere, we propose an IR attenuation imaging model. Finally, various IR images of city buildings at different time in a day and at different detected distance are realistically rendered based on our model.
In recent years, there has been a growing need for accurate, high fidelity scene simulations in the visible, infrared, microwave and other wavelengths. Based on a rigorous material classification and incorporating material attribute information, we generate wavelength independent texture maps for multi-spectral scene simulation. We calculate the sensor radiance value of every pixel, and change them into color or gray. If a single pixel in the texture contains more than one material, we mixture them based on their radiation attribution. According to area consistency and coherence across scan lines, an extended Seed Filling Algorithm is used in those areas with same or similar materials. These optical steps are performed repeatedly until a satisfactory classfication and mixture is found and the texture maps in a certain wave band are obtained. In this way we generate infrared textures from visible maps and different simulation scence textures at different time of day and under different environment conditions can also be obtained. Finally we give some examples of multi-spectral scene simulation, which are quite satisfied compared with the measured images.
We establish an IR model for ground target such as tank considering the effect of inner heat source, friction and various environmental factors and draw IR images of target at various states using the techniques of Computer Graphics. We then propose a thermal model for different grounds using 1D finite difference method to calculate the surface temperature changing with time. The result are quite satisfied compared with the measured values. Also the re- distributing of temperature field after the touch between targets and ground is calculated and the realistic IR synthesis images of targets and the ground background are drawn. Finally by using the methods of 3D finite difference, we successfully calculate and render RI shadow which describes the effect of higher temperature distribution of the center area originally occupied by targets than that of the around area after the targets are driven away. We also draw different IR images of the ground at the different intervals after the targets have been driven away. Based on these IR images, we can determine the existence of the IR targets some certain interval ago.