3D Toolkit Research Articles

Targetless Coregistration of Terrestrial Laser Scanning Point Clouds Using a Multi Surrounding Scan Image-Based Technique

The coregistration of terrestrial laser point clouds is widely investigated where different techniques are presented to solve this problem. The techniques are divided either as target-based or targetless approaches for coarse and fine coregistration. The targetless approach is more challenging since no physical reference targets are placed in the field during the scanning. Mainly, targetless methods are image-based and they are applied through projecting the point clouds back to the scanning stations. The projected 360 point cloud images are normally in the form of panoramic images utilizing either intensity or RGB values, and an image matching is followed to align the scan stations together. However, the point cloud coregistration is still a challenge since ICP like methods are applicable for fine registration. Furthermore, image-based approaches are restricted when there is: a limited overlap between point clouds, no RGB data accompanied to intensity values, and unstructured scanned objects in the point clouds. Therefore, we present in this paper the concept of a multi surrounding scan MSS image-based approach to overcome the difficulty to register point clouds in challenging cases. The multi surrounding scan approach means to create multi-perspective images per laser scan point cloud. These multi-perspective images will offer different viewpoints per scan station to overcome the viewpoint distortion that causes the failure of the image matching in challenging situations. Two experimental tests are applied using point clouds collected in Enschede city and the published 3D toolkit data set in Bremen city. The experiments showed a successful coregistration approach even in challenging settings with different constellations.

The Root-Cause Analysis on Failed Patient-Specific Measurements of Pencil-Beam-Scanning Protons

The purpose of this study is to present the root-cause analysis on failed patient-specific quality assurance (QA) measurements of pencil-beam-scanning (PBS) protons; referred to as PBS-QA measurement.A criterion to fail a PBS-QA measurement is having a < 95% passing-rate in a 3.0%-3.0mm Gamma-index analysis. The 2D Gamma-index analysis toolkit was clinically used to obtain the passing-rate. A 2D detection array with finite-size ionization-chamber was utilized.A total 2488 PBS-QA measurements were catalogued. The percentage of measurements for the sites of Head/Neck, Breast, Prostate, and Other are 53.3%, 22.7%, 10.5%, and 13.5% respectively. The percentage of measurements with a passing rate of 100%-to-95%, 94%-to-89%, and < 89% were 93.6%, 5.6%, and 0.8% respectively. The percentage of failed measurements with a < 95% passing rate was 10.9%. 8.1% became acceptable by either re-measurement or re-analysis to remove the setup or user errors. A feature of > 3% per-mm dose gradient along depth of beam path was observed on the failed measurements. To study the effect of depth dose gradient, a 3D Gamma-index analysis toolkit was used. 43.1% of measurements improved using this 3D toolkit. A feature among measurements that remained sub-optimal was a sharp > 3% per-mm lateral dose gradient that may not be well handled by using the detector size of 5.0mm in-diameter. An analysis of the sampling of finite-size detectors using 1D error function showed a large dose deviation at locations of low doses in a valley between two plateaus. User error, large depth dose gradient, and the effect of detector-size are identified.With an understanding and mitigation of these root causes, the goals of patient-specific QA, specifically detecting actual deviation of beam delivery or identifying limitations of dose calculation algorithm in used treatment planning system, can be directly related to the failure of PBS-QA measurements.

The root cause analysis on failed patient-specific measurements of pencil beam scanning protons using a 2D detection array with finite size ionization chambers.

The aim of this report is to present the root cause analysis on failed patient‐specific quality assurance (QA) measurements of pencil beam scanning (PBS) protons; referred to as PBS‐QA measurement. A criterion to fail a PBS‐QA measurement is having a <95% passing rate in a 3.0%‐3.0 mm gamma index analysis. Clinically, we use a two‐dimensional (2D) gamma index analysis to obtain the passing rate. The IBA MatriXX PT 2D detection array with finite size ionization chamber was utilized. A total of 2488 measurements performed in our PBS beamline were cataloged. The percentage of measurements for the sites of head/neck, breast, prostate, and other are 53.3%, 22.7%, 10.5%, and 13.5%, respectively. The measurements with a passing rate of 100 to >94%, 94 to >88%, and <88% were 93.6%, 5.6%, and 0.8%, respectively. The percentage of failed measurements with a <95% passing rate was 10.9%. After removed the user errors of either re‐measurement or re‐analysis, 8.1% became acceptable. We observed a feature of >3% per mm dose gradient with respect to depth on the failed measurements. We utilized a 2D/three‐dimensional (3D) gamma index analysis toolkit to investigate the effect of depth dose gradient. By utilizing this 3D toolkit, 43.1% of the failed measurements were improved. A feature among measurements that remained sub‐optimal after re‐analysis was a sharp >3% per mm lateral dose gradient that may not be well handled using the detector size of 5.0 mm in‐diameter. An analysis of the sampling of finite size detectors using one‐dimensional (1D) error function showed a large dose deviation at locations of low‐dose areas between two high‐dose plateaus. User error, large depth dose gradient, and the effect of detector size are identified as root causes. With the mitigation of the root causes, the goals of patient‐specific QA, specifically detecting actual deviation of beam delivery or identifying limitations of the dose calculation algorithm of the treatment planning system, can be directly related to failure of the PBS‐QA measurements.

Targetless Coregistration of Terrestrial Laser Scanning Point Clouds Using a Multi Surrounding Scan Image-Based Technique

The coregistration of terrestrial laser point clouds is widely investigated where different techniques are presented to solve this problem. The techniques are divided either as target-based or targetless approaches for coarse and fine coregistration. The targetless approach is more challenging since no physical reference targets are placed in the field during the scanning. Mainly, targetless methods are image-based and they are applied through projecting the point clouds back to the scanning stations. The projected 360 point cloud images are normally in the form of panoramic images utilizing either intensity or RGB values, and an image matching is followed to align the scan stations together. However, the point cloud coregistration is still a challenge since ICP like methods are applicable for fine registration. Furthermore, image-based approaches are restricted when there is: a limited overlap between point clouds, no RGB data accompanied to intensity values, and unstructured scanned objects in the point clouds. Therefore, we present in this paper the concept of a multi surrounding scan MSS image-based approach to overcome the difficulty to register point clouds in challenging cases. The multi surrounding scan approach means to create multi-perspective images per laser scan point cloud. These multi-perspective images will offer different viewpoints per scan station to overcome the viewpoint distortion that causes the failure of the image matching in challenging situations. Two experimental tests are applied using point clouds collected in Enschede city and the published 3D toolkit data set in Bremen city. The experiments showed a successful coregistration approach even in challenging settings with different constellations.

3D Mass Customization Toolkits Design, Part I: Survey and an Evaluation Model

Mass customization (MC) allows consumers to design their own products or services through online MC toolkits. The application of geometric modeling through modern web-browsers allows for the presentation of a virtual 3D product, resulting in a number of commercial 3D MC sites. To gain a deeper understanding of the toolkits that drive these sites, this article provides a comprehensive investigation into web-based toolkit design. Based on this review, an evaluation model for 3D MC toolkits is proposed that considers four aspects: Individual Differences, Solution Space, Interaction Design and Enabling Technologies. This leads to a follow-up article that applies the 3D toolkit evaluation model to assess commercial 3D toolkits which are available on the current market.

TOWARDS GLOBALLY CONSISTENT SCAN MATCHINGWITH GROUND TRUTH INTEGRATION

Abstract. The scan matching based simultaneous localization and mapping method with six dimensional poses is capable of creating a three dimensional point cloud map of the environment, as well as estimating the six dimensional path that the vehicle has travelled. The essence of it is the registering and matching of sequentially acquired 3D laser scans, while moving along a path, in a common coordinate frame in order to provide 6D pose estimations at the respective positions, as well as create a three dimensional map of the environment. An approach that could drastically improve the reliability of acquired data is to integrate available ground truth information. This paper is about implementing such functionality as a contribution to 6D SLAM (simultaneous localization and mapping with 6 DoF) in the 3DTK – The 3D Toolkit software (Nüchter and Lingemann, 2011), as well as test the functionality of the implementation using real world datasets.

Serious games: virtual reality’s second coming?

The 1980s and 1990s were marked by a series of important events in the history of interactive computer graphics. Significant evolutions in real-time hardware and software prompted the launch of a number of ‘‘movements’’ throughout the globe, including computer-generated imagery and animation (e.g. for the film and TV industries), scientific visualisation, Virtual Reality and wearable computing. Whilst these groups did much to bring a range of unique technologies to the attention of a much wider global audience than ever before, they were also responsible for creating a culture of myth, hype and false promise. This was particularly the case for VR. From the perspective of potential adopters throughout many commercial sectors (including defence and medicine), VR delivered a roller coaster ride of achievement and failure throughout the 1990s. Factors such as commercial naivety on the part of VR companies, significant failures to deliver meaningful and usable intellectual property on the part of so-called academic ‘‘centres of excellence’’, expensive and unreliable hardware, an absence of case studies with cost-benefit analyses and a widespread absence of attention to the requirements and limitations of the end users, all took their toll by the end of the 1990s. However, long before the late 1980s, when VR broke free from its NASA and Department of Defense ‘‘shackles’’, the future potential of computer games to solve the accessibility and affordability problems of modelling and rendering tools for ‘‘serious’’ interactive 3D applications had already been recognised. Battlezone—a wireframe tank game published in 1983 for the Atari—represented a true breakthrough in the exploitation of games technology for part-task training. Less well remembered, but representing a major step forward in interactive 3D was The Colony—an excellent first-person space survival game created in 1988 for the Apple Macintosh by David Smith (who was also accredited with developing the first VRML Internet tool kit in 1995). Smith’s game development software, which was commercialised as a 3D toolkit (Virtus WalkThrough) when he founded the Virtus Corporation in 1990, was subsequently modified for use as a virtual scene planning tool for the science fiction film The Abyss and later formed the basis of a relationship with Tom Clancy that was to spawn such memorable titles as SSN and Rainbow Six. From the late 1990s, the ‘‘serious games’’ community steadily built up significant momentum, exploiting the powerful software underpinning such games as the Unreal, Quake and Half-Life series, Operation Flashpoint, FarCry and many more. Much has been written about serious games, particularly with regard to the future of gaming in simulation and training. It is generally accepted that they are games with ‘‘a purpose’’—games that go beyond entertainment to deliver engaging learning experiences across a wide range of sectors. Since 2005, it is fair to say that, whilst serious games still have some way to go before conclusive statements can be made as to their training efficacy (promoting positive skills or knowledge transfer and minimising skill fade, for example), their appearance on the technologybased training stage in many countries has, in the main, met with surprisingly positive receptions. This is despite the fact that the term ‘‘serious games’’ seems to have attracted as many opponents as proponents and there still exists a good population of sceptics who are still recovering from R. Stone (&) Human Interface Technologies Team, School of Electronic, Electrical and Computer Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK e-mail: r.j.stone@bham.ac.uk