3D Image Reconstruction Based On Range-gated Laser Imaging System

Because the water and haze condition have serious optical attenuation, so the visible distance is short,the contrast is low and visual effect is poor of the imaging system in this environment. Improve optoelectronic image clarity and imaging system detection performance is very important to the optoelectronic imaging detection in the serious optical attenuation. Range-gated laser imaging system is a “distance tomography” imaging technology, through control the delay between range-gate and laser pulse to imaging target in the special distance, the image have advantage in clear, high contrast, strong anti-interference capacity and, effected by environment and et al, so Range-gated laser imaging technology has become a key technology in China and abroad. China and abroad have extensively research in system miniaturization, noise reduction and enhancement to range image, real-time image processing and et al, it has become a mature photo electronic imaging system.3D imaging reconstruction technology is combine imaging system operating principle, according to 2D image to restore 3D information. 3D image can make us more clearly understand the 3D information of the target, it has great application prospect in remote sensing imagery analysis, military reconnaissance, robot navigation, virtual reality, manufacture, industry exploration and et al. Due to the “distance tomography” imaging mode of Range-gated laser imaging system, so 3D imaging reconstruction is possible based this technology. In China and abroad have some research on 3D imaging reconstruction based on Range-gated laser imaging system, and through combine some method achieved 3D imaging reconstruction based on Range-gated laser imaging technology.In this paper analyzed three method on 3D imaging reconstruction based on Range-gate laser imaging technology, it’s “slices method”, “centroid calibrate method” and “gain modulation method”. Analysis indicates: “ slices method” need acquire step delay range-gated image sequence, through deal with the range-gated image sequence to make the 3D imaging reconstruction of the target come true, but the reconstructing precision is decided by range gate, so need to use narrow gate to achieve high precision 3D reconstruction. “centroid calibrate method” also need step delay range-gated image sequence, but through the research we know that the centroid of the range-gated image sequence and target location is monotonous relation. We set the range gate and stepped size to 5ns and use the Gaussian temporal shape of laser pulse as the illumination sources to simulate, the result show that the relationship between target location and image sequence centroid is linear. This method of 3D reconstruction don’t have theoretic error and special requirement to the Range-gated laser imaging system. “Gain modulation method” through modulate the target reflected laser pulse by two types MCP gain, it’s linear gain and horizontal gain, to acquire the image under the two types MCP gain. To solve the every pixel value ratio of the two image, research show that the ratio and target location is linear relation. This reconstruction method also don’t have theoretic error, but MCP modulate result is very important to the reconstructing precision, so need to modulate the image intensifier MCP in the range gate very precisely.This paper based on Range-gated laser imaging system in laboratory conduct the error analyze and calibrate prove. Theory shows that centroid and target location is linear, so we design experiment to prove the relation, the result is same with the theory. Design the experiment to detection the precision of the calibrate result, the result shows that mean error less than 1cm. Experiments shows that this 3D reconstruction method have error in two categories, bent on the spot in global and undulate error in small range. We propose can using correction matrix and noise filtration to conduct the two categories error.