Efficient, simultaneous vision ray calibration and system orientation for high precision geometric-optical 3D-measurement systems

适用于高精度几何光学 3D 测量系统的高效、同步视觉射线校准和系统定向

• 批准号: 289307220
• 负责人: Professor Dr. Ralf Bernhard Bergmann
• 金额: --
• 依托单位: BIAS - Bremer Institut für Angewandte Strahltechnik GmbH
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/289307220?language=en
• 关键词: Efficient; simultaneous; vision; ray; calibration

Imaging optical metrology allows high-density, highly accurate, fast and non-contact acquisition of 3D data for quality control. The majority of the methods used are characterised by light rays propagating in straight lines and can be summarised under the term geometric-optical measurement technique. Since the image captured by the camera in the measuring system image is two-dimensional, no direct point-to-point mapping to 3D coordinates is possible; instead, a half-line, the so-called vision or sight ray, emanates from every pixel. Usually these assignments are determined by a camera calibration based on the so-called conventional pinhole camera model. It is assumed that the sight rays from all pixels run through a common point, the so-called pinhole aperture. Real lens systems, however, cannot be adequately characterised by this model. A more recent approach describes the sight rays for each pixel individually. Thus the calibration provides an individual 3D-half-line for each pixel, which offers the highest possible accuracy but is computationally very complex. Also, the smallest possible number of reference recordings is not known, and the possibility for theoretical predictions is curtailed by the quasi-model-free approach of the vision-ray calibration technique. Still, the most common method of camera calibration for metrological purposes is based on an extended pinhole camera model. For low-uncertainty geometric-optical measuring instruments, this approach is unsatisfactory because certain distortion and lens errors cannot be captured and corrected in this way.The aim of the proposed project is the realisation of a new method for the simultaneous implementation of vision-ray camera calibration and multi-camera measurement system orientation by developing new, numerically efficient and geometrically optimal calibration algorithms and strategies that will greatly simplify the calibration of multi-camera 3D coordinate measurement systems based on fringe projection. The project is divided into three sub-objectives: 1. Creation of a complete multi-camera simulation model of sight-ray calibration to investigate various model components, to test numerical optimization methods used and to explore multi-camera calibration methods. 2. Derivation of a specification for the camera line of sight calibration describing the minimal set of reference display positions that are necessary to maintain the uncertainty achieved with currently used methods. The measurement time shal be reduced from several hours to a maximum of 30 min. 3. Development of a calibration method for multi-camera set-ups that significantly reduces the number of recording steps by simultaneous calibration and orientation. Here the measurement effort shall be reduced to 45 min for a two-camera system and to 60 min in a system with four cameras.

成像光学计量可实现高密度、高精度、快速且非接触式的 3D 数据采集，以进行质量控制。所使用的大多数方法的特点是光线沿直线传播，并且可以概括为术语几何光学测量技术。由于测量系统图像中相机捕获的图像是二维的，因此无法直接点对点映射到 3D 坐标；相反，半线，即所谓的视觉或视线，从每个像素发出。通常，这些分配是通过基于所谓的传统针孔相机模型的相机校准来确定的。假设来自所有像素的视线穿过一个公共点，即所谓的针孔孔径。然而，该模型无法充分表征真实的透镜系统。更新的方法单独描述每个像素的视线。因此，校准为每个像素提供单独的 3D 半线，这提供了尽可能高的精度，但计算起来非常复杂。此外，参考记录的最小可能数量是未知的，并且视觉射线校准技术的准无模型方法限制了理论预测的可能性。尽管如此，用于计量目的的最常见的相机校准方法是基于扩展的针孔相机模型。对于低不确定度的几何光学测量仪器，这种方法不能令人满意，因为无法以这种方式捕获和校正某些畸变和镜头误差。该项目的目的是实现一种同时实现视觉射线的新方法通过开发新的、数值高效且几何优化的校准算法和策略，可以极大地简化基于条纹投影的多相机 3D 坐标测量系统的校准。该项目分为三个子目标： 1. 创建完整的视线标定多相机仿真模型，以研究各种模型组件，测试所使用的数值优化方法并探索多相机标定方法。 2. 推导相机视线校准规范，描述维持当前使用的方法所实现的不确定性所必需的最小参考显示位置集。测量时间应从几个小时减少到最长 30 分钟。 3. 开发多摄像机设置的校准方法，通过同时校准和定向，显着减少记录步骤的数量。在此，双摄像头系统的测量工作量应减少至 45 分钟，四摄像头系统的测量工作量应减少至 60 分钟。