基于实验室设备自主开发了一套320 kV锥束工业CT成像系统。首先设计了基于运动控制卡的六轴机械扫描平台,并将其与320 kV射线机、平板探测器结合搭建了锥束CT成像系统的硬件。其次,利用平板探测器和运动控制卡的动态链接库开发锥束CT投...基于实验室设备自主开发了一套320 kV锥束工业CT成像系统。首先设计了基于运动控制卡的六轴机械扫描平台,并将其与320 kV射线机、平板探测器结合搭建了锥束CT成像系统的硬件。其次,利用平板探测器和运动控制卡的动态链接库开发锥束CT投影数据采集软件和重建软件,自主开发FDK算法并基于CUDA架构实现FDK算法的GPU加速。最后,采用阻尼器对锥束CT成像系统进行测试。结果表明,整个系统运行稳定,可以获得高质量的CT重建图像,且重建效果与VG STUDIO MAX 3.4软件的重建效果一致。展开更多
In this article we present our system for scalable,robust,and fast city-scale reconstruction from Internet photo collections(IPC)obtaining geo-registered dense 3D models.The major achievements of our system are the ef...In this article we present our system for scalable,robust,and fast city-scale reconstruction from Internet photo collections(IPC)obtaining geo-registered dense 3D models.The major achievements of our system are the efficient use of coarse appearance descriptors combined with strong geometric constraints to reduce the computational complexity of the image overlap search.This unique combination of recognition and geometric constraints allows our method to reduce from quadratic complexity in the number of images to almost linear complexity in the IPC size.Accordingly,our 3D-modeling framework is inherently better scalable than other state of the art methods and in fact is currently the only method to support modeling from millions of images.In addition,we propose a novel mechanism to overcome the inherent scale ambiguity of the reconstructed models by exploiting geo-tags of the Internet photo collection images and readily available StreetView panoramas for fully automatic geo-registration of the 3D model.Moreover,our system also exploits image appearance clustering to tackle the challenge of computing dense 3D models from an image collection that has significant variation in illumination between images along with a wide variety of sensors and their associated different radiometric camera parameters.Our algorithm exploits the redundancy of the data to suppress estimation noise through a novel depth map fusion.The fusion simultaneously exploits surface and free space constraints during the fusion of a large number of depth maps.Cost volume compression during the fusion achieves lower memory requirements for high-resolution models.We demonstrate our system on a variety of scenes from an Internet photo collection of Berlin containing almost three million images from which we compute dense models in less than the span of a day on a single computer.展开更多
以线管式稀土钨阴极高温静电除尘器为研究对象,基于计算流体力学和直接模拟蒙特卡洛(Direct simulation of Monte Carlo,DSMC)方法的数学模型,建立高压电场条件下静电除尘器内部气、电、固多相流场模型,分析了高温静电除尘器的除尘特性...以线管式稀土钨阴极高温静电除尘器为研究对象,基于计算流体力学和直接模拟蒙特卡洛(Direct simulation of Monte Carlo,DSMC)方法的数学模型,建立高压电场条件下静电除尘器内部气、电、固多相流场模型,分析了高温静电除尘器的除尘特性,为除尘工艺参数优化提供了理论依据。将针对稀土钨阴极材料的含有温度项的电流密度经验公式引入到电场模型中,从而简化了颗粒在温度场下的受力情况。通过与实验结果的对比,验证了该模型的准确性。模拟结果表明降低气流速度,提高荷电电压都能使除尘效率显著提高。粉尘粒径越大最容易去除,提高温度可以改善线管式除尘性能。展开更多
文摘基于实验室设备自主开发了一套320 kV锥束工业CT成像系统。首先设计了基于运动控制卡的六轴机械扫描平台,并将其与320 kV射线机、平板探测器结合搭建了锥束CT成像系统的硬件。其次,利用平板探测器和运动控制卡的动态链接库开发锥束CT投影数据采集软件和重建软件,自主开发FDK算法并基于CUDA架构实现FDK算法的GPU加速。最后,采用阻尼器对锥束CT成像系统进行测试。结果表明,整个系统运行稳定,可以获得高质量的CT重建图像,且重建效果与VG STUDIO MAX 3.4软件的重建效果一致。
文摘In this article we present our system for scalable,robust,and fast city-scale reconstruction from Internet photo collections(IPC)obtaining geo-registered dense 3D models.The major achievements of our system are the efficient use of coarse appearance descriptors combined with strong geometric constraints to reduce the computational complexity of the image overlap search.This unique combination of recognition and geometric constraints allows our method to reduce from quadratic complexity in the number of images to almost linear complexity in the IPC size.Accordingly,our 3D-modeling framework is inherently better scalable than other state of the art methods and in fact is currently the only method to support modeling from millions of images.In addition,we propose a novel mechanism to overcome the inherent scale ambiguity of the reconstructed models by exploiting geo-tags of the Internet photo collection images and readily available StreetView panoramas for fully automatic geo-registration of the 3D model.Moreover,our system also exploits image appearance clustering to tackle the challenge of computing dense 3D models from an image collection that has significant variation in illumination between images along with a wide variety of sensors and their associated different radiometric camera parameters.Our algorithm exploits the redundancy of the data to suppress estimation noise through a novel depth map fusion.The fusion simultaneously exploits surface and free space constraints during the fusion of a large number of depth maps.Cost volume compression during the fusion achieves lower memory requirements for high-resolution models.We demonstrate our system on a variety of scenes from an Internet photo collection of Berlin containing almost three million images from which we compute dense models in less than the span of a day on a single computer.
文摘以线管式稀土钨阴极高温静电除尘器为研究对象,基于计算流体力学和直接模拟蒙特卡洛(Direct simulation of Monte Carlo,DSMC)方法的数学模型,建立高压电场条件下静电除尘器内部气、电、固多相流场模型,分析了高温静电除尘器的除尘特性,为除尘工艺参数优化提供了理论依据。将针对稀土钨阴极材料的含有温度项的电流密度经验公式引入到电场模型中,从而简化了颗粒在温度场下的受力情况。通过与实验结果的对比,验证了该模型的准确性。模拟结果表明降低气流速度,提高荷电电压都能使除尘效率显著提高。粉尘粒径越大最容易去除,提高温度可以改善线管式除尘性能。
