基于分区标定的相机畸变校正研究

针对应用张氏标定法进行图像畸变校正存在的校正不足和过度校正问题,本文采用分区标定的方式对标定方法进行改进。通过将相机视场进行均匀分区并获取分区标定参数,并对分区标定结果进行研究分析,以新的畸变校正方式对图像进行校正,解决了小畸变相机的过度校正问题。为了验证本文方法的准确性和实用性,本文将对比不同校正方法校正后的立体匹配结果。实验结果表明:本文方法相比传统方法在平面度测量上有所提高,有一定的借鉴作用。

基于结构光视觉技术的圆柱度测量新方法

针对机器视觉测量轴类零件的圆柱度误差时因使用畸变严重的鱼眼镜头影响测量精度的问题,提出了一种基于结构光视觉技术的圆柱度测量新方法。该方法投射的结构光与被测轴轴线方向近似平行,考虑轴类零件的特征和鱼眼镜头畸变分布的规律,将视场分为多个区域进行畸变修正。给出了结构光分区标定的模型、测量数据的提取及数据转换的方法。通过对标准轴的测量检验了本文方法的可行性和准确性,实验结果表明,直径为27.68mm、长为300mm的轴的圆柱度的测量精度为20μm。该方法不仅满足产品几何技术规范的采样要求,而且具有非接触、高效、在线测量的特点,能为圆柱度的精确评定提供可靠的数据信息。

宽视场光学设备畸变修正方法

光学畸变是宽视场光学设备测角精度的主要影响因素,通过深入分析研究现有光学畸变修正方法,提出了基于视场分区标定建立光学畸变多修正多模型的新方法。通过实验表明,该方法可以有效的提高宽视场光学设备的测量精度,特别适用于成像探测器像元尺寸较大的宽视场光学设备的畸变高精度修正,为连发齐射多目标、快速目标、大动态目标等弹道高精度测量提供了技术支撑。

A new technique for high precision sub-regional camera calibration based on checkerboard pattern

Camera calibration is critical in computer vision measurement system, affecting the accuracy of the whole system. Many camera calibration methods have been proposed, but they cannot consider precision and operation complexity at the same time. In this paper, a new technique is proposed to calibrate camera. Firstly, the global calibration method is described in de-tail. It requires the camera to observe a checkerboard pattern shown at a few different orientations. The checkerboard corners are obtained by Harris algorithm. With direct linear transformation and non-linear optimal algorithm, the global calibration pa-rameters are obtained. Then, a sub-regional method is proposed. Those corners are divided into two groups, middle corners and edge corners, which are used to calibrate the corresponding area to get two sets of calibration parameters. Finally, some experimental images are used to test the proposed method. Experimental results demonstrate that the average projection error of sub-region method is decreased at least 16% compared with the global calibration method. The proposed technique is simple and accurate. It is suitable for the industrial computer vision measurement.

Distribution and quantitative zonation of unloading cracks at a proposed large hydropower station dam Site

Rock mass unloading is an important rock engineering problem because unloading may impact the stability of a rock mass slope. Based on hydroelectric engineering principles, this study focuses on the classification of unloading zones to reflect the rock mass structure characteristics. Geological background and slope structure of the study region were considered to investigate the distribution and deformation of the unloading process. Quantitative indices were classified according to the formation mechanisms and the geological exhibition of unloading zones. The P-wave velocity(V_P), the ratio of the wave velocity(V_p) the ratio of the test P-wave velocity along the adit depth to the P-wave velocity of intact rock, the sum of joint openings every 2 meters(S_t), and the density of open joints(D_t) were calculated as quantitative indices for the rock mass unloading zone. The characteristics of the unloading zone of rock mass slopes at the dam site were successfully determined. The method of combining qualitative data with quantitative indices was found to be effective for the classification of slope unloading zones.

圆形渐变滤光片光谱辐射计辐射定标

基于分区线性法对圆形渐变滤光片型光谱辐射计开展辐射定标研究,以解决温度范围大、工作波段宽的测量目标对该类型光谱辐射计造成的非线性问题。所提光谱辐射计的主要技术原理是将待测目标的温度区间分为多个子区间,采集目标温度区间内多个不同温度黑体对应的测量光谱,并计算各个温度下的响应度函数。在进行红外光谱测量时,将目标光谱与区间内记录的不同温度点光谱进行比对,从而确定待测目标所属温度子区间的上下限。根据子区间计算的响应度函数,通过线性插值求得待测目标的响应度函数并进行辐射定标。基于该方法的实验结果表明,待测目标理论辐亮度与使用分区线性法进行辐射定标得到的辐亮度在波长范围内的平均偏差小于1%。通过定标结果反演测量黑体的等效温度,等效温度误差小于2%。

一种2～14μm红外光谱辐射计的辐射定标方法

提出了一种分区多点标定的辐射定标方法。定标原理如下:将测量目标的温度区间分为n个子区间,测量并记录目标温度区间内n+1个不同温度黑体对应的红外光谱辐射计输出数据,并分别计算各个子区间的定标系数;进行红外光谱辐射测量时,比对红外光谱辐射计输出数据和记录数据,确定待测目标所属温度子区间;使用对应子区间的定标系数进行辐射定标,以提高测量精度。使用该方法对研制的渐变滤光片型红外光谱辐射计进行辐射定标,并根据定标结果反演测量黑体的等效亮温温差。实验结果表明,该方法的辐射定标精度优于1.5 K,可应用于红外光谱辐射计的辐射定标。