scholarly journals Congruence analysis of point clouds from unstable stereo image sequences

2014 ◽  
Vol XL-5 ◽  
pp. 301-306 ◽  
Author(s):  
C. Jepping ◽  
F. Bethmann ◽  
T. Luhmann
Keyword(s):  
High Speed ◽  
Image Data ◽  
Point Clouds ◽  
Image Sequences ◽  
Stereo Image ◽  
Free Form ◽  
Crash Test ◽  
3D Point Clouds ◽  
Congruence Analysis ◽  
Free Form Surfaces

This paper deals with the correction of exterior orientation parameters of stereo image sequences over deformed free-form surfaces without control points. Such imaging situation can occur, for example, during photogrammetric car crash test recordings where onboard high-speed stereo cameras are used to measure 3D surfaces. As a result of such measurements 3D point clouds of deformed surfaces are generated for a complete stereo sequence. The first objective of this research focusses on the development and investigation of methods for the detection of corresponding spatial and temporal tie points within the stereo image sequences (by stereo image matching and 3D point tracking) that are robust enough for a reliable handling of occlusions and other disturbances that may occur. The second objective of this research is the analysis of object deformations in order to detect stable areas (congruence analysis). For this purpose a RANSAC-based method for congruence analysis has been developed. This process is based on the sequential transformation of randomly selected point groups from one epoch to another by using a 3D similarity transformation. The paper gives a detailed description of the congruence analysis. The approach has been tested successfully on synthetic and real image data.

scholarly journals An Efficient Probabilistic Registration Based on Shape Descriptor for Heritage Field Inspection

2020 ◽  
Vol 9 (12) ◽  
pp. 759
Author(s):  
Yufu Zang ◽  
Bijun Li ◽  
Xiongwu Xiao ◽  
Jianfeng Zhu ◽  
Fancong Meng
Keyword(s):  
Cultural Heritage ◽  
Solution Space ◽  
Point Clouds ◽  
Shape Descriptor ◽  
Free Form ◽  
Registration Method ◽  
Field Inspection ◽  
3D Point Clouds ◽  
Quality Issues ◽  
Cultural Heritage Objects

Heritage documentation is implemented by digitally recording historical artifacts for the conservation and protection of these cultural heritage objects. As efficient spatial data acquisition tools, laser scanners have been widely used to collect highly accurate three-dimensional (3D) point clouds without damaging the original structure and the environment. To ensure the integrity and quality of the collected data, field inspection (i.e., on-spot checking the data quality) should be carried out to determine the need for additional measurements (i.e., extra laser scanning for areas with quality issues such as data missing and quality degradation). To facilitate inspection of all collected point clouds, especially checking the quality issues in overlaps between adjacent scans, all scans should be registered together. Thus, a point cloud registration method that is able to register scans fast and robustly is required. To fulfill the aim, this study proposes an efficient probabilistic registration for free-form cultural heritage objects by integrating the proposed principal direction descriptor and curve constraints. We developed a novel shape descriptor based on a local frame of principal directions. Within the frame, its density and distance feature images were generated to describe the shape of the local surface. We then embedded the descriptor into a probabilistic framework to reject ambiguous matches. Spatial curves were integrated as constraints to delimit the solution space. Finally, a multi-view registration was used to refine the position and orientation of each scan for the field inspection. Comprehensive experiments show that the proposed method was able to perform well in terms of rotation error, translation error, robustness, and runtime and outperformed some commonly used approaches.

Measurement of Surface Changes in a Scaled-Down Landslide Model Using High-Speed Stereo Image Sequences

2016 ◽  
Vol 82 (7) ◽  
pp. 547-557 ◽  
Author(s):  
Tiantian Feng ◽  
Huan Mi ◽  
Marco Scaioni ◽  
Gang Qiao ◽  
Ping Lu ◽  
...  
Keyword(s):  
High Speed ◽  
Image Sequences ◽  
Stereo Image ◽  
Landslide Model ◽  
Surface Changes

Computing Cutter Engagement Values in Milling Tessellated Free-Form Surfaces

2010 ◽  
Vol 10 (4) ◽  
Author(s):  
Zhiyang Yao ◽  
Ajay Joneja
Keyword(s):  
Computational Model ◽  
Cutting Force ◽  
High Speed ◽  
Tool Path ◽  
Free Form ◽  
High Speed Milling ◽  
Free Form Surfaces ◽  
Potential Use ◽  
Do So

High speed milling (HSM) has great potential use in die/mold cutting, but traditional machining plans do exploit HSM capabilities effectively. An important consideration in HSM is to limit cutting force variations, and one way to do so is to reduce cutter-workpiece engagement (CWE) variations. CWE is measured as the area of the tool instantaneously engaged with the part. Estimating CWE as a function of the tool path requires repeated, expensive computations. This paper develops algorithms for a discretized computational model to make CWE computations for arbitrary shaped parts.

Digital Measurement and its Error Analysis for the Machining Free-Form Surface

2014 ◽  
Vol 664 ◽  
pp. 263-267
Author(s):  
Feng Lu ◽  
Ning Li ◽  
Xiao Fei Zhang
Keyword(s):  
Laser Scanning ◽  
Optical Measurement ◽  
Three Dimensional ◽  
Point Clouds ◽  
Free Form ◽  
Digital Measurement ◽  
Machining Errors ◽  
Three Dimensional Measurement ◽  
Free Form Surface ◽  
Free Form Surfaces

To deal with the lack of accurate and efficient inspection methods in complex free-form surfaces, three-dimensional measurement method based on the optical measurement and computer image processing technology was proposed. It adopted laser scanning technology to get point clouds of free-form surface. Used rapid measurement software to inspect precision of point cloud& CAD model. What could be the cause of machining errors was analyzed. 3D deviation inspection of complex surfaces was applied by an artifact. Detected the machining error of an important section, and outputted test report. This research provides a convenient and swift method for the inspection of free-form surface and processing quality control.

Sign in / Sign up

Export Citation Format

Share Document