Tim McCarthy

Automated road markings extraction from mobile laser scanning data

Abstract Road markings are used to provide guidance and instruction to road users for safe and comfortable driving. Enabling rapid, cost-effective and comprehensive approaches to the maintenance of route networks can be greatly improved with detailed information about location, dimension and condition of road markings. Mobile Laser Scanning (MLS) systems provide new opportunities in terms of collecting and processing this information. Laser scanning systems enable multiple attributes of the illuminated target to be recorded including intensity data. The recorded intensity data can be used to distinguish the road markings from other road surface elements due to their higher retro-reflective property. In this paper, we present an automated algorithm for extracting road markings from MLS data. We describe a robust and automated way of applying a range dependent thresholding function to the intensity values to extract road markings. We make novel use of binary morphological operations and generic knowledge of the dimensions of road markings to complete their shapes and remove other road surface elements introduced through the use of thresholding. We present a detailed analysis of the most applicable values required for the input parameters involved in our algorithm. We tested our algorithm on different road sections consisting of multiple distinct types of road markings. The successful extraction of these road markings demonstrates the effectiveness of our algorithm.

Dual-scale validation of a medium-resolution coastal DEM with terrestrial LiDAR DSM and GPS

The use of medium-resolution photogrammetric-derived Digital Elevation Models (DEMs) to model coastal inundation risk is commonplace in the geosciences. However, these datasets are often characterised by relatively large and loosely defined elevation errors, which can seriously limit their reliability. Post-processed and static RTK dual-frequency GPS data and very high-resolution Terrestrial Laser Scanning DSM data are used here to quantify the magnitude and spatial distribution of elevation error on a 10km coastal section of a medium-resolution photogrammetric DEM. The validation data are captured at two scales and spatial-resolutions to minimise the risk of spatial bias in the validation results. The strengths and shortcomings of each validation dataset are assessed, and the complimentary value of GPS and Terrestrial Laser Scanning for external validation is demonstrated. Elevation errors highlighted in the photogrammetric DEM are found to be significantly larger than suggested by the data suppliers, with a tendency for the larger errors to occur with increasing proximity to the coastline. The results confirm the unsuitability of the DEM tested for the local spatial modelling of coastal inundation risk, highlighting difficulties that may be prone to occur when similar DEM datasets are used in coastal studies elsewhere.

Understanding the Geography of Post-Traumatic Stress: An Academic Justification for Using a Spatial Video Acquisition System in the Response to Hurricane Katrina

In the aftermath of a disaster like Hurricane Katrina, remote-sensing methods are often employed in an effort to assess damage. However, their utility may be limited by the aerial perspective and image resolution. The Spatial Video Acquisition System (SVAS), in conjunction with a Geographic Information System (GIS), has the potential to be a complementary methodology for obtaining damage assessment information as well as capturing recovery related geographies associated with post-traumatic stress. An example is provided from the Lower 9th Ward of New Orleans with data that could be used to predict neighborhood post-traumatic stress. Results reveal six dimensions in which a SVAS can improve existing disaster-related data collection approaches: organization, archiving, transferability, evaluation, objectivity, and feasibility.

Pharmaceutical process validation: An overview:

Abstract Drugs are critical elements in health care. They must be manufactured to the highest quality levels. End-product testing by itself does not guarantee the quality of the product. Quality assurance techniques must be used. In the pharmaceutical industry, process validation performs this task, ensuring that the process does what it purports to do. It is also a regulatory requirement. This paper presents an introduction and general overview of this process, with special reference to the requirements stipulated by the US Food and Drug Administration (FDA).

Portable X-ray fluorescence as a rapid technique for surveying elemental distributions in soil

ABSTRACT Case studies from two sites demonstrate how concentration distributions of hazardous contaminants can be rapidly measured and visualized using portable XRF (X-ray fluorescence) coupled with geostatistical interpolation tools. In this study, lead is used as an exemplar due to its well-known detrimental effect on human health through long-term exposure. A portable Thermo Scientific NITON X-ray fluorescence (XRF) instrument was used for real-time in-situ concentration measurements, which were linked to GPS coordinates of the sampling locations. A 52 point mixed sampling density survey was performed at a site near Maynooth, Co. Kildare, and a second 58 survey undertaken at Dublin City University (DCU). At Maynooth, high concentrations of Pb (above 110 mg/kg) were found close to the site where a local canal meets a road. At the DCU site, results indicate high Pb concentrations (above 160 mg/kg) near a busy main road. Geostatistical techniques were used to generate concentration prediction and critical threshold contour surfaces for both sites. Linked with GPS coordinates for each sampling location, this technology enables the distribution of multiple elements to be mapped over wide areas in a relatively short time. Supplemental materials are available for this article. Go to the publishers online edition of Spectroscopy Letters to view the supplemental file.

Integrating aerial videography and digital photography with terrain modelling: an application for coastal geomorphology

The integration of airborne imagery, derived from video and digital camera imagery, with terrain data from ground survey is within the scope of low-budget, small scale geomorphological investigations. Geographical Information Systems (GIS), available on standard desktop computer systems, are suitable for the integration of this imagery with other geomorphological survey data. Different georeferenced datasets can be combined to produce visualisations that can aid interpretation and measurement that may otherwise be difficult to achieve. As with all remote-sensed data, the synoptic view has considerable benefits, especially when combined with ground fieldwork. There are a variety of methods that can be used to collect and process these data dependent upon the aims of the geomorphologist. There is always a trade-off involving the cost, spatial resolution and temporal control for each of these methods, and this trade-off ultimately determines the absolute accuracy and suitability of the imagery for the purposes required. Although it always seems desirable to attempt to collect the highest resolution imagery possible, using the greatest degree of control and results that can enhance the value of standard field techniques. Decisions involving choice of capture equipment, methods of processing, methods of establishing position and attitude, and ground control techniques determine the quality of the imagery produced. The rectified imagery, when combined with digital terrain models, significantly aids the interpretative process and enables features with boundaries visible on the ground to be delimited on the terrain model and related to contour plots. Airborne video is a cheap, easily available and flexible method of producing this imagery. Recent advances in digital techniques have resulted in digital video and digital camera photography becoming alternatives to conventional video. The advantage of using a digital format is that the number of processing steps is reduced with potential savings in equipment, cost and time as well as improvements in resolution and accuracy. Digital camera photography shows particular promise with spectacular improvements in image resolution and continually falling costs making it an increasingly viable alternative to standard photographic film, particularly when the data are to be transferred onto a computer system. The accuracy and resolution that can be obtained are superior to those obtainable from orbiting systems and future availability of sensors covering a variety of bandwidths will enable multi-spectral analysis. The combination of this kind of imagery with terrain data is a powerful one, either for data visualisation and interpretation or for feature definition and measurement of change.

LiDAR data management pipeline; from spatial database population to web-application visualization

While the existence of very large and scalable Database Management Systems (DBMSs) is well recognized, it is the usage and extension of these technologies to managing spatial data that has seen increasing amounts of research work in recent years. A focused area of this research work involves the handling of very high resolution Light Detection and Ranging (LiDAR) data. While LiDAR has many real world applications, it is usually the purview of organizations interested in capturing and monitoring our environment where it has become pervasive. In many of these cases, it has now become the de facto minimum standard expected when a need to acquire very detailed 3D spatial data is required. However, significant challenges exist when working with these data sources, from data storage to feature extraction through to data segmentation all presenting challenges relating to the very large volumes of data that exist. In this paper, we present the complete LiDAR data pipeline as managed in our spatial database framework. This involves three distinct sections, populating the database, building a spatial hierarchy that describes the available data sources, and spatially segmenting data based on user requirements which generates a visualization of these data in a WebGL enabled web-application viewer. All work presented is in an experimental results context where we show how this approach is runtime efficient given the very large volumes of LiDAR data that are being managed.

Georeferenced four-dimensional virtual environments: principles and applications

Abstract This paper introduces and defines the concept of a four-dimensional virtual environment as “multidimensional/multimedia representations of phenomena in natural and built environments permitting the realistic monitoring, analysis and evaluation of the component phenomena”. It is argued that current geographic information systems cannot handle these representations and so new tools need to be built. This paper describes two applications of virtual environments: the first is an application which can link oblique or vertical aerial videography to map or surface models in real-time, while the second example is an application which links a user-browseable virtual world with a map. The paper concludes by suggesting that the approaches demonstrated here are indicative of what the next generation of geographic information handling might look like.

Influence of Basalt Fiber on Performance of Cement Mortar

This paper presents initial work with the application of basalt fiber (BF) in the field of reinforced cement composites. Effect of BF on mortar drying shrinkage, mechanical prosperities and bond performance were studied. The results showed that adding of BF reduced markedly dry shrinkage of mortar especially at early ages. BF mortar had a greater compressive and flexural strength at early hydration period，but had a little less strength at the age of 28-days than mortar without fiber. Four point bending tests shows that addition of BF increased effectively toughness of mortar specimen at 28-days at the same loading, but had not a remarkable effect on fracture strength. A good bond was observed between BF and mortar matrix interface zone by SEM in early ages and there was debonding phenomenon between BF and mortar matrix in the long-term ages.

Knowledge Management in the Designer/Constructor interface

In construction projects there are a number of information exchange and sharing interfaces between the designers and the contractors. This paper explores the evolution of these interfaces during a project and identifies the critical success factors for knowledge management in this domain. The specific phase of tender stage briefing is examined as it lays the foundation for efficient exchange of information throughout the project. Furthermore, the paper also examines the activities and flow of information throughout the entire project for one key aspect, namely, geotechnical and site investigation information. A formal activity model in IDEF0 and an information model in EXPRESS are presented for the domain of geotechnical information. These indicate the role of formal modelling of the knowledge/information flow in a project. This paper describes work that forms part of a project entitled Knowledge Learning In CONstruction (KLICON).