Mobile capture of remote points of interest using line of sight modelling

Recording points of interest using GPS whilst working in the field is an established technique in geographical fieldwork, where the user’s current position is used as the spatial reference to be captured; this is known as geo-tagging. We outline the development and evaluation of a smartphone application called Zapp that enables geo-tagging of any distant point on the visible landscape. The ability of users to log or retrieve information relating to what they can see, rather than where they are standing, allows them to record observations of points in the broader landscape scene, or to access descriptions of landscape features from any viewpoint. The application uses the compass orientation and tilt of the phone to provide data for a line of sight algorithm that intersects with a Digital Surface Model stored on the mobile device. We describe the development process and design decisions for Zapp present the results of a controlled study of the accuracy of the application, and report on the use of Zapp for a student field exercise. The studies indicate the feasibility of the approach, but also how the appropriate use of such techniques will be constrained by current levels of precision in mobile sensor technology. The broader implications for interactive query of the distant landscape and for remote data logging are discussed

Multi-dimensional modelling for the national mapping agency: a discussion of initial ideas, considerations, and challenges

The Ordnance Survey, the National Mapping Agency (NMA) for Great Britain, has recently begun to research the possible extension of its 2-dimensional geographic information into a multi-dimensional environment. Such a move creates a number of data creation and storage issues which the NMA must consider. Many of these issues are highly relevant to all NMA’s and their customers alike, and are presented and explored here. This paper offers a discussion of initial considerations which NMA’s face in the creation of multi-dimensional datasets. Such issues include assessing which objects should be mapped in 3 dimensions by a National Mapping Agency, what should be sensibly represented dynamically, and whether resolution of multi-dimensional models should change over space. This paper also offers some preliminary suggestions for the optimal creation method for any future enhanced national height model for the Ordnance Survey. This discussion includes examples of problem areas and issues in both the extraction of 3-D data and in the topological reconstruction of such. 3-D feature extraction is not a new problem. However, the degree of automation which may be achieved and the suitability of current techniques for NMA’s remains a largely unchartered research area, which this research aims to tackle. The issues presented in this paper require immediate research, and if solved adequately would mark a cartographic paradigm shift in the communication of geographic information – and could signify the beginning of the way in which NMA’s both present and interact with their customers in the future

Digital Urban - The Visual City

Nothing in the city is experienced by itself for a city’s perspicacity is the sum of its surroundings. To paraphrase Lynch (1960), at every instant, there is more than we can see and hear. This is the reality of the physical city, and thus in order to replicate the visual experience of the city within digital space, the space itself must convey to the user a sense of place. This is what we term the “Visual City”, a visually recognisable city built out of the digital equivalent of bricks and mortar, polygons, textures, and most importantly data. Recently there has been a revolution in the production and distribution of digital artefacts which represent the visual city. Digital city software that was once in the domain of high powered personal computers, research labs and professional software are now in the domain of the public-at-large through both the web and low-end home computing. These developments have gone hand in hand with the re-emergence of geography and geographic location as a way of tagging information to non-proprietary web-based software such as Google Maps, Google Earth, Microsoft’s Virtual Earth, ESRI’s ArcExplorer, and NASA’s World Wind, amongst others. The move towards ‘digital earths’ for the distribution of geographic information has, without doubt, opened up a widespread demand for the visualization of our environment where the emphasis is now on the third dimension. While the third dimension is central to the development of the digital or visual city, this is not the only way the city can be visualized for a number of emerging tools and ‘mashups’ are enabling visual data to be tagged geographically using a cornucopia of multimedia systems. We explore these social, textual, geographical, and visual technologies throughout this chapter

Assessing handheld mobile laser scanners for forest surveys

Abstract: A handheld mobile laser scanning (HMLS) approach to forest inventory surveying allows virtual reconstructions of forest stands and extraction of key structural parameters from beneath the canopy, significantly reducing survey time when compared against static laser scan and fieldwork methods. A proof of concept test application demonstrated the ability of this technique to successfully extract diameter at breast height (DBH) and stem position compared against a concurrent terrestrial laser scan (TLS) survey. When stems with DBH > 10 cm are examined, an HMLS to TLS modelling success rate of 91% was achieved with the root mean square error (RMSE) of the DBH and stem position being 1.5 cm and 2.1 cm respectively. The HMLS approach gave a survey coverage time per surveyor of 50 m 2/min compared with 0.85 m2/min for the TLS instrument and 0.43 m2/min for the field study. This powerful tool has potential applications in forest surveying by providing much larger data sets at reduced operational costs to current survey methods. HMLS provides an efficient, cost effective, versatile forest surveying technique, which can be conducted as easily as walking through a plot, allowing much more detailed, spatially extensive survey data to be collected

Integration of LiDAR and stereoscopic imagery for route corridor surveying

Transportation networks are, typically, one of the most economic valuable resources for any nation requiring a large percentage of GDP to build and maintain. These route corridors attract their own unique set of spatial information requirements in terms of overall management including planning, engineering and operation. Various disciplines within a road management agency require high quality, spatial data of objects and features occurring along these networks from road infrastructure, sub-surface pavement condition through to modelling noise. This paper examines the integration of relatively novel sensor data against some pressing spatial information requirements for a small European road management agency. LiDAR systems are widely available and now used to record data from both aerial and terrestrial survey platforms. One of the chief LiDAR outputs are X,Y,Z points enabling a reliable 2.5-D geometric surface to be produced. Stereoscopic imagery is also collected from similar airborne and terrestrial mobile platforms. Both provide different datasets in terms of their respective optical and geometric properties. For example, stereoscopic cameras mounted on a survey vehicle record different data compared to LiDAR mounted near vertically on an airborne platform. Airborne LiDAR provides a more comprehensive geometric record whereas stereoscopic imagery can be used to provide a more comprehensive visual descriptor of the immediate route corridor. Acquisition systems for both sensors are relatively well understood and developed. Both systems collect large volumes of data that require a significant amount of data processing in order to produce useful information. A more efficient result can be achieved by integrating these two datasets within a GIS. The preliminary results of integration of airborne LiDAR with ground based stereo imaging systems are presented. How well this integration satisfies the growing spatial information requirements of the road agency are also examined

Mapping for Indoor Walking Environment from Point Clouds by Using Mobile Mapping Systems

Walkability is one of the issues to be addressed in the planning of smart urban cities. Although, there is a substantial amount of studies on outdoor walking pedestrian, limited study has been done to address indoor walkability. Recently, most of the pedestrians are likely to use indoor route than outdoor route to protect themselves from sun and rain as most of the indoor routes are located on the buildings such as shopping mall and rail transit station. Therefore, it important to collect all the relevant information in the indoor building to addressed the walkability issues. The GeoSLAM ZEB REVO scanner is used for its convenience to access narrow space, busy area and complex building structure. This scanner is portable and easy to handle by the operator as it can be attached on the cart or carry it with backpack. The scanner captures the building geometry and facilities and present it in the form of point cloud. Then necessary information can be extracted from the point cloud using point cloud segmentation method. The end user such as town planner can benefit from the final product to design future building with pedestrian-friendly tool to encourage more people to walk. Therefore, it brings impact to the society by providing the healthy lifestyle in addition to reducing the use of private vehicle on the road