为了对高速公路车辆速度进行限制,建立了基于卷帘式CMOS(Complementary Metal Oxide Semiconductor)图像传感器的相机测速系统,并对该系统采用的标定技术、测速算法等进行了研究。卷帘式快门数字相机测量速度是利用卷帘式快门曝光,具有...为了对高速公路车辆速度进行限制,建立了基于卷帘式CMOS(Complementary Metal Oxide Semiconductor)图像传感器的相机测速系统,并对该系统采用的标定技术、测速算法等进行了研究。卷帘式快门数字相机测量速度是利用卷帘式快门曝光,具有一定的延时,对运动物体拍摄会产生一定的畸变,通过对图像的畸变部分进行图像处理和计算,即可得到运动物体的速度参数。根据相机成像的几何原理,分析了相机的标定原理,根据相机测速时的特点,提出了简单、有效的标定方法。进一步研究了相机标定和测速的实验方法和步骤,进行了标定及测速实验。经实验验证:利用卷帘式快门CMOS数字相机方法对运动目标测速值较精确,误差在2.5%以内。基本满足高速公路相机测速系统精度要求。展开更多
Background: Taxicab drivers have high homicide rates compared to all worker occupations. To help taxi fleets select effective taxicab security cameras, this project tested eight sample taxicab security cameras for det...Background: Taxicab drivers have high homicide rates compared to all worker occupations. To help taxi fleets select effective taxicab security cameras, this project tested eight sample taxicab security cameras for determining their photographic quality which correlated to the effectiveness of in-taxicab facial identification. Methods: Five photographic quality metric thresholds: 1) resolution, 2) highlight dynamic range, 3) shadow dynamic range, 4) lens distortion, and 5) shutter speed, were employed to evaluate the photographic quality of the sample cameras. Waterproof tests and fire-resistive tests on recording memory cards were conducted to determine the memory card survivability in water and simulated fire. Results: The Full-HD (1920 × 1080 pixels), HD (1280 × 720 pixels) and dual-lens VGA (2 × 640 × 480 pixels with wide-angle and telephoto lenses) cameras performed well in resolution tests in daylight conditions. The resolution of a single-lens VGA (640 × 480 pixels) camera did not meet the resolution minimum requirements. All of the recording memory cards passed the five-meter/72-hour waterproof test. A fire resistant chamber made with one fire insulation material could protect a single memory card at 538°C/1000°F for a five-minute simulated fire test. Conclusions: Single-lens VGA-resolution (640 × 480 pixels) cameras are not suggested for use as security cameras in taxicabs with two or more rows of seats. The recording memory cards can survive 5-meter/72-hour waterproof tests. The memory card chamber built with an existing heat insulation material can protect an individual memory card during 538°C?(1000°F)/5-minute fire resistance oven-test.展开更多
文摘为了对高速公路车辆速度进行限制,建立了基于卷帘式CMOS(Complementary Metal Oxide Semiconductor)图像传感器的相机测速系统,并对该系统采用的标定技术、测速算法等进行了研究。卷帘式快门数字相机测量速度是利用卷帘式快门曝光,具有一定的延时,对运动物体拍摄会产生一定的畸变,通过对图像的畸变部分进行图像处理和计算,即可得到运动物体的速度参数。根据相机成像的几何原理,分析了相机的标定原理,根据相机测速时的特点,提出了简单、有效的标定方法。进一步研究了相机标定和测速的实验方法和步骤,进行了标定及测速实验。经实验验证:利用卷帘式快门CMOS数字相机方法对运动目标测速值较精确,误差在2.5%以内。基本满足高速公路相机测速系统精度要求。
文摘Background: Taxicab drivers have high homicide rates compared to all worker occupations. To help taxi fleets select effective taxicab security cameras, this project tested eight sample taxicab security cameras for determining their photographic quality which correlated to the effectiveness of in-taxicab facial identification. Methods: Five photographic quality metric thresholds: 1) resolution, 2) highlight dynamic range, 3) shadow dynamic range, 4) lens distortion, and 5) shutter speed, were employed to evaluate the photographic quality of the sample cameras. Waterproof tests and fire-resistive tests on recording memory cards were conducted to determine the memory card survivability in water and simulated fire. Results: The Full-HD (1920 × 1080 pixels), HD (1280 × 720 pixels) and dual-lens VGA (2 × 640 × 480 pixels with wide-angle and telephoto lenses) cameras performed well in resolution tests in daylight conditions. The resolution of a single-lens VGA (640 × 480 pixels) camera did not meet the resolution minimum requirements. All of the recording memory cards passed the five-meter/72-hour waterproof test. A fire resistant chamber made with one fire insulation material could protect a single memory card at 538°C/1000°F for a five-minute simulated fire test. Conclusions: Single-lens VGA-resolution (640 × 480 pixels) cameras are not suggested for use as security cameras in taxicabs with two or more rows of seats. The recording memory cards can survive 5-meter/72-hour waterproof tests. The memory card chamber built with an existing heat insulation material can protect an individual memory card during 538°C?(1000°F)/5-minute fire resistance oven-test.
