共查询到18条相似文献,搜索用时 140 毫秒
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内方位元素测试仪是测量航测相机的主点、主距及畸变的仪器。本文介绍了内方位元素测试仪光学系统设计,包括光学参数、结构形式的确定,成象质量和最终设计结果. 相似文献
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文章简单介绍了数字航测相机的特点 ,电子系统的组成 ,配电总体的作用。分析了飞机直流电源系统的特点 ,给出了配电系统采取的相应措施。以及为保证系统的电磁兼容性 ,在配线方面采取的相应措施。 相似文献
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文章简单介绍了数字航测相机的特点,电子系统的组成,配电总体的作用。分析了飞机直流电源系统的特点,给出了配电系统采取的相应措施。以及为保证系统的电磁兼容性,在配线方面采取的相应措施。 相似文献
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由于需要对大面阵航空CCD相机带来的庞大航测图像数据进行压缩,在研究多种图像压缩算法的基础上提出了一种基于比特位平面编码的码率预分配图像压缩算法(RPCA)。首先将图像进行多级整数小波变换,以去除图像像素之间相关冗余。根据率失真理论并结合各个子带对图像重建质量的重要性原则,编码前事先确定每个子带在总码率一定的情况下各个子带在实际编码中应当分配的码率大小,再利用自适应MQ算术编码对每个子带比特平面进行熵编码,从而得到细致的嵌入式码流。实验仿真结果表明,该RPCA码率分配精准,图像压缩质量与JPEG2000标准相当,且支持无损到有损的任意倍率图像压缩,但复杂度低于JPEG2000标准,适合于硬件的高速实现。 相似文献
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关于数字航摄像机(DMC)若干问题的探讨及研究 总被引:1,自引:0,他引:1
数码航摄像机是直接获取高精度数字影像的重要手段之一,本文介绍了最完善的用于高精度、高分辨率的航空摄影测量任务的数字航摄像机(Digital Mapping Camera,简称DMC)系统、结构及其关键技术;着重分析了它们与中心投影的关系及成像原理,并指出这种航空数码像机相对于其他各类像机的优缺点。 相似文献
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AbstractAccuracy, flexibility and cost effectiveness are advantages of using digitized aerial photographs as a data source for remote sensing studies of the environment, such as forests. However, the relationship between the resolution of digital images and the aerial photographs from which they were derived must be addressed to ensure valid application using the environmental data. This communication considers issues that affect the information content of environmental data through the spatial resolution of photographs and digitized images, and suggests how users can optimize the spatial resolution of the latter by selecting an appropriate scanning aperture. An optimal scanning aperture can be chosen by considering the combination of the resolving power of the camera system, the scale of the original photograph and the desired pixel size of the digital image. Optimizing spatial resolution while scanning will maximize the spatial information obtained from the original photographs without generating unnecessarily large file sizes. The authors make several recommendations for the digitization of aerial photographs for environmental applications, such as analyses of forests. 相似文献
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基于CCD的航空相机自动检焦系统 总被引:1,自引:0,他引:1
要使航空相机获得高质量的图像,必须保证镜头的焦距和实际成像面的位置符合技术要求。提出了一种自动检测航空相机焦距和是否离焦(实际成像面的位置是否在焦深范围内)的系统,论述了系统的工作原理、硬件组成和软件设计。该系统采用平行光管产生检焦信息,利用CCD摄像头作光电转换器件接收图像,采用重心法处理数据,由光电线位移传感器和光栅数显表共同作用实现摄像头轴向的精确平移,从而能够确定相机的最佳成像位置和图像尺寸。最佳图像位置用来判断是否离焦,最佳图像尺寸用来计算焦距。使用该系统对航空相机镜头焦距的检测准确率达到99.87%、是否离焦的判断与试飞结果完全相同。 相似文献
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The field of view of digital in-line holography for flow field diagnostics is restricted to a small volume due to the finite size and the low spatial resolution of the available CCD. Expansion of the measurement cross section of digital holographic particle image velocimetry was investigated with a lens-based holography configuration. By sampling the chirp signal in the center lobe completely and undersampling the chirp signal in the second- and higher-order lobes by a magnified virtual recording plane produced by an imaging camera lens, the field of view is expanded. Simulation results show that the three-dimensional (3D) location and size of the relatively large particle can be reconstructed with good accuracy. A digital holographic particle image velocimetry system was established for coal particle flow field diagnostics. Compared with the lensless configuration, the field of view of the digital holography system was enlarged 1.9 times, up to 2.78 cm × 2.78 cm × 3 cm. The 3D location, size distribution, and the 3D vector field of coal powder were obtained. The results show that the application of digital in-line holography to measure large particle flow field is feasible. 相似文献
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飞机姿态变化是影响航空相机成像质量的关键因素,尤其是飞机进行大坡度转弯将影响航空相机照相分辨率和重叠率。采用公式推理、坐标旋转变换等方法详细分析了飞机大坡度转弯对相机照相分辨率和重叠率的影响,并以摆扫型全景相机为例,给出了飞机大坡度转弯时相机的像移模型,分析结果表明:飞机大坡度转弯过程中相机产生的最大前向像移量接近4个像素,需要进行像移补偿;而垂直飞行方向上的最大像移量小于1/8像元,对成像分辨率影响不大。依据分析结果对像移模型进行了简化,为像移补偿提供了理论依据。针对飞机大坡度转弯对照相重叠率的影响,提出了依据转弯半径和转弯角速率调整曝光时间的方法加以解决。上述分析为摆扫相机在大坡度转弯时获取高质量图像提供了理论依据。 相似文献
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To apply digital holography to the measurement of three-dimensional dense particle fields in large facilities, we have developed a hybrid digital holographic particle-imaging system. The technique combines the advantages of off-axis (side) scattering in suppressing speckle noise and on-axis (in-line) recording in lowering the digital sensor resolution requirement. A camera lens is attached to the digital sensor to compensate for the weak object wave from side scattering over a large recording distance. A simple numerical reconstruction algorithm is developed for holograms recorded with a lens without requiring complex and impractical mathematical corrections. We analyze the effect of image sensor resolution and off-axis angle on system performance and quantify the particle positioning accuracy of the system. The holographic system is successfully applied to the study of inertial particle clustering in isotropic turbulence. 相似文献
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