Point Cloud to CAD Model Registration Methods in Manufacturing Inspection

2006 ◽  
Vol 6 (4) ◽  
pp. 418-421 ◽  
Author(s):  
Thomas M. Tucker ◽  
Thomas R. Kurfess
Keyword(s):  
Computer Vision ◽  
Virtual World ◽  
Point Cloud ◽  
Physical World ◽  
Coordinate Frame ◽  
Cad Model ◽  
Modern Computer ◽  
Coordinate Metrology ◽  
Flow Of Information

Modern computer vision and coordinate metrology systems provide an ever-increasing flow of information from the physical world we live in to the virtual world inside computer systems. Often the coordinate system of the metrology device has a different coordinate frame from that of the existing objects in the virtual world. To rectify these differences, a process called registration is often applied. This paper uses a case study to highlight the differences between various registration techniques.

Everyone in Space Wants to Hear You Scream

2020 ◽  
Vol 1 (3) ◽  
pp. 15-34
Author(s):  
Stephen Tatlow
Keyword(s):  
Virtual Worlds ◽  
Social Communication ◽  
Virtual World ◽  
Physical World ◽  
Virtual Space ◽  
Game World ◽  
Character Identity ◽  
Marketing Materials

When considering player voice in the context of game sound, existing examinations remain inconclusive. As player voice exists in a liminal position between reality and virtuality, some academics see them as sonic violations of the game space. Voice can convey information about identity, which may oppose our understanding of the avatars within the game world. Voice can facilitate social communication, which may remind us of the physical world outside the virtuality. Mediations of voice into the virtual world may introduce obstacles or inflections that interfere with our enjoyment of the virtual space. Alongside these concerns, however, we can also find virtual worlds that prioritize and privilege player voice. Player voice can become part of character identity. Gameworlds can encourage us to communicate ludically, without disrupting immersion. Interruptions and disruptions can be limited by players. Amongst others, the virtual world of the long-running MMORPG EVE Online demonstrates how voice can coexist with immersion. Marketing materials for the game now place player voice at the center of consumer focus. Including an interview with one of the videographers who placed player voice at the center of his fan videos, the article uses EVE Online as a case study for the integration of player voice into virtual worlds. By examining virtual worlds and the role of voice within them, this article develops a framework for understanding player voice in the context of game sound. This allows us to recognize how player voice, an often overlooked aspect of game sound, can function within virtual worlds.

Implementing Point Assignment Using Octrees and GPU

2007 ◽  
Author(s):  
Koushik V. Aravalli ◽  
Thomas R. Kurfess ◽  
Thomas M. Tucker
Keyword(s):  
Point Cloud ◽  
Point Clouds ◽  
Computer Hardware ◽  
Model Complexity ◽  
Data Sets ◽  
Cad Model ◽  
Point Set Registration ◽  
Coordinate Metrology ◽  
Point Set ◽  
Processor Unit

Data point set registration is an important operation in coordinate metrology. Registration is the operation by which sampled point clouds are aligned with a CAD model by a 4×4 homogeneous transformation (e.g., rotation and translation). This alignment permits validation of the produced artifact’s geometry. Registration is an iterative nonlinear optimization operation assigning points on the CAD model for the sampled points. The objective is to minimize the sum of the squares of the normal distances between each point in the point cloud and the closest point in the CAD model. State-of-the-art metrology systems are now capable of generating thousands, if not millions, of data points during an inspection operation, resulting in increased computational power to fully utilize these larger data sets. The execution time for assigning the point set in registration process is directly related to the number of points processed and CAD model complexity. A brute force approach to registration, which is often used, is to compute the minimum distance between each sampled point and its normal projection on the CAD model. As the point cloud size and CAD model complexity increase, this approach becomes intractable and inefficient. This paper proposes a new approach to efficiently identify the closest point in the CAD model for a given point. This approach employs a combination of readily available computer hardware, graphical processor unit (GPU) and a formulation of the point assignment problem, using an octree data structure that is suited for execution on the GPU.

ON METHODS OF OBJECT DETECTION IN VIDEO STREAMS

2017 ◽  
Vol 2 (1) ◽  
pp. 80-87
Author(s):  
Puyda V. ◽  
◽  
Stoian. A.
Keyword(s):  
Computer Vision ◽  
Object Detection ◽  
Open Source ◽  
Feature Detection ◽  
Video Stream ◽  
Object Identification ◽  
Vision Systems ◽  
Modern Computer ◽  
Computer Vision Systems ◽  
Open Source Hardware

Detecting objects in a video stream is a typical problem in modern computer vision systems that are used in multiple areas. Object detection can be done on both static images and on frames of a video stream. Essentially, object detection means finding color and intensity non-uniformities which can be treated as physical objects. Beside that, the operations of finding coordinates, size and other characteristics of these non-uniformities that can be used to solve other computer vision related problems like object identification can be executed. In this paper, we study three algorithms which can be used to detect objects of different nature and are based on different approaches: detection of color non-uniformities, frame difference and feature detection. As the input data, we use a video stream which is obtained from a video camera or from an mp4 video file. Simulations and testing of the algoritms were done on a universal computer based on an open-source hardware, built on the Broadcom BCM2711, quad-core Cortex-A72 (ARM v8) 64-bit SoC processor with frequency 1,5GHz. The software was created in Visual Studio 2019 using OpenCV 4 on Windows 10 and on a universal computer operated under Linux (Raspbian Buster OS) for an open-source hardware. In the paper, the methods under consideration are compared. The results of the paper can be used in research and development of modern computer vision systems used for different purposes. Keywords: object detection, feature points, keypoints, ORB detector, computer vision, motion detection, HSV model color

Toward a Philosophical Approach of the Hermeneutics of the Qur’an

2006 ◽  
Vol 23 (1) ◽  
pp. 15-34
Author(s):  
Aliaa Ibrahim Dakroury
Keyword(s):  
Modern Technology ◽  
Interesting Case ◽  
Philosophical Approach ◽  
True Meaning ◽  
Flow Of Information ◽  
The Relationship

Although claims questioning whether religious sacred books can be “translated” or not have been heard for quite some time, they have increased with the emergence of globalization and the increasing openness and flow of information due to modern technology. In the context of the relationship between hermeneutics and communication, one could argue that interpreting the Qur’an is an interesting case study for many reasons. Among them is the number of debates and discourses that have been raised both for and against its translation. Another reason, perhaps one of the largest barriers according to some religious Muslim groups, is that the Qur’an is fundamentally revealed and written in Arabic, and, therefore, its true meaning cannot be translated into another language. Certain verses, such as “It is a Qur’an in Arabic, without any crookedness (therein): in order that they may guard against evil” (28:39), have been presented to support this argument.

scholarly journals Back to reality: transition techniques from short HMD-based virtual experiences to the physical world

2021 ◽  
Author(s):  
Robin Horst ◽  
Ramtin Naraghi-Taghi-Off ◽  
Linda Rau ◽  
Ralf Dörner
Keyword(s):  
Virtual Reality ◽  
Virtual World ◽  
Visual Cues ◽  
User Study ◽  
Physical World ◽  
Direct Communication ◽  
Common Presentation ◽  
Presentation Media ◽  
Virtual Experiences ◽  
Short Times

AbstractEvery Virtual Reality (VR) experience has to end at some point. While there already exist concepts to design transitions for users to enter a virtual world, their return from the physical world should be considered, as well, as it is a part of the overall VR experience. We call the latter outro-transitions. In contrast to offboarding of VR experiences, that takes place after taking off VR hardware (e.g., HMDs), outro-transitions are still part of the immersive experience. Such transitions occur more frequently when VR is experienced periodically and for only short times. One example where transition techniques are necessary is in an auditorium where the audience has individual VR headsets available, for example, in a presentation using PowerPoint slides together with brief VR experiences sprinkled between the slides. The audience must put on and take off HMDs frequently every time they switch from common presentation media to VR and back. In a such a one-to-many VR scenario, it is challenging for presenters to explore the process of multiple people coming back from the virtual to the physical world at once. Direct communication may be constrained while VR users are wearing an HMD. Presenters need a tool to indicate them to stop the VR session and switch back to the slide presentation. Virtual visual cues can help presenters or other external entities (e.g., automated/scripted events) to request VR users to end a VR session. Such transitions become part of the overall experience of the audience and thus must be considered. This paper explores visual cues as outro-transitions from a virtual world back to the physical world and their utility to enable presenters to request VR users to end a VR session. We propose and investigate eight transition techniques. We focus on their usage in short consecutive VR experiences and include both established and novel techniques. The transition techniques are evaluated within a user study to draw conclusions on the effects of outro-transitions on the overall experience and presence of participants. We also take into account how long an outro-transition may take and how comfortable our participants perceived the proposed techniques. The study points out that they preferred non-interactive outro-transitions over interactive ones, except for a transition that allowed VR users to communicate with presenters. Furthermore, we explore the presenter-VR user relation within a presentation scenario that uses short VR experiences. The study indicates involving presenters that can stop a VR session was not only negligible but preferred by our participants.

Authoritarianism and anonymity

2021 ◽  
Vol 49 (3) ◽  
pp. 19-27
Author(s):  
Michael Heron ◽  
Pauline Belford
Keyword(s):  
Computer Ethics ◽  
Teaching Tool ◽  
Academic Context ◽  
Modern Computer ◽  
Culture Of Fear ◽  
Multiple Groups ◽  
The University ◽  
Witch Hunts

The Scandal in Academia [32] [33] [34] [35] is an extended fictional case-study intended for use as a teaching and discussion aid for educational practitioners looking to introduce elements of computer ethics into their curricula. Inspired by Epstein [17] [18] it is a full-cycle scenario involving many individuals which touches upon the complexity and interrelations of modern computer ethics. It has been trailed and evaluated as a teaching tool by the authors [36] and with multiple groups since then. However its utility as a general resource is limited without the academic context that supports deeper investigation of the material. It is to address this issue that the authors offer this commentary on the Scandal, with a focus on the ninth and tenth newspaper items presented within. Specifically these are Culture of Fear and Nepotism at University and Witch-Hunts at the University - IT Crackdown Causes Criticisms.

scholarly journals Measurement of Gem Colour Using a Computer Vision System: A Case Study with Jadeite-Jade

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 791
Author(s):  
Sufei Zhang ◽  
Ying Guo
Keyword(s):  
Computer Vision ◽  
Regression Model ◽  
Vision System ◽  
Expert Group ◽  
Group Test ◽  
System A ◽  
Real Objects ◽  
Practical Tool ◽  
Almost All

This paper introduces computer vision systems (CVSs), which provides a new method to measure gem colour, and compares CVS and colourimeter (CM) measurements of jadeite-jade colour in the CIELAB space. The feasibility of using CVS for jadeite-jade colour measurement was verified by an expert group test and a reasonable regression model in an experiment involving 111 samples covering almost all jadeite-jade colours. In the expert group test, more than 93.33% of CVS images are considered to have high similarities with real objects. Comparing L*, a*, b*, C*, h, and ∆E* (greater than 10) from CVS and CM tests indicate that significant visual differences exist between the measured colours. For a*, b*, and h, the R2 of the regression model for CVS and CM was 90.2% or more. CVS readings can be used to predict the colour value measured by CM, which means that CVS technology can become a practical tool to detect the colour of jadeite-jade.

scholarly journals A computer vision-based object detection and counting for COVID-19 protocol compliance: a case study of Jakarta

2020 ◽  
Author(s):  
Muhammad Lanang Afkaar Ar ◽  
Sulthan Muzakki Adytia S ◽  
Yudhistira Nugraha ◽  
Farizah Rizka R ◽  
Andy Ernesto ◽  
...  
Keyword(s):  
Computer Vision ◽  
Object Detection ◽  
Detection And Counting ◽  
Protocol Compliance

scholarly journals MATLAB Virtual Toolbox for Retrospective Rockfall Source Detection and Volume Estimation Using 3D Point Clouds: A Case Study of a Subalpine Molasse Cliff

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Dario Carrea ◽  
Antonio Abellan ◽  
Marc-Henri Derron ◽  
Neal Gauvin ◽  
Michel Jaboyedoff
Keyword(s):  
Point Cloud ◽  
Natural Hazard ◽  
Point Clouds ◽  
Volume Estimation ◽  
Natural Phenomena ◽  
Frequency Distributions ◽  
Erosion Rates ◽  
3D Point Clouds

The use of 3D point clouds to improve the understanding of natural phenomena is currently applied in natural hazard investigations, including the quantification of rockfall activity. However, 3D point cloud treatment is typically accomplished using nondedicated (and not optimal) software. To fill this gap, we present an open-source, specific rockfall package in an object-oriented toolbox developed in the MATLAB® environment. The proposed package offers a complete and semiautomatic 3D solution that spans from extraction to identification and volume estimations of rockfall sources using state-of-the-art methods and newly implemented algorithms. To illustrate the capabilities of this package, we acquired a series of high-quality point clouds in a pilot study area referred to as the La Cornalle cliff (West Switzerland), obtained robust volume estimations at different volumetric scales, and derived rockfall magnitude–frequency distributions, which assisted in the assessment of rockfall activity and long-term erosion rates. An outcome of the case study shows the influence of the volume computation on the magnitude–frequency distribution and ensuing erosion process interpretation.

Solution space reduction of disassembly sequences generated automatically via computer aids

2014 ◽  
Vol 229 (16) ◽  
pp. 2977-2986 ◽  
Author(s):  
Louisa Issaoui ◽  
Nizar Aifaoui ◽  
Abdelmajid Benamara
Keyword(s):  
Solution Space ◽  
Target Component ◽  
Cad Model ◽  
Simulation Tool ◽  
Sequence Generation ◽  
Space Solution ◽  
Space Reduction ◽  
Automatic Sequence ◽  
Selective Disassembly

To develop a simulation tool for automatic disassembly in computer aid design (CAD) environment two difficulties are found: the huge space of generated sequences and their feasibility especially in combinatory generation. This article deals with automatic sequence generation for selective disassembly of mechanical product. Starting from a CAD model a new appropriate connection tree of a target component is constructed. This tree aims at reducing space solution by eliminatory rules. The generation of sequence is based on reading of connection tree branches and eliminatory tests of feasibility. The feasibility is checked by updating the disassembly mobility of each sequence’s element. A case study is presented to prove the effectiveness of the proposed approach.

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