All Topics

A B C D E F G H I J K L M N O P R S T U V W
AM-94 - Machine Learning Approaches

Machine learning approaches are increasingly used across numerous applications in order to learn from data and generate new knowledge discoveries, advance scientific studies and support automated decision making. In this knowledge entry, the fundamentals of Machine Learning (ML) are introduced, focusing on how feature spaces, models and algorithms are being developed and applied in geospatial studies. An example of a ML workflow for supervised/unsupervised learning is also introduced. The main challenges in ML approaches and our vision for future work are discussed at the end.

CV-34 - Map Icon Design

The use of map icons is an efficient way to condense a map object into a concise expression of geospatial data. Like all cartographic design, map icon design merges artistic and scientific elements into symbolic representations intended to be readily legible to map readers. This entry reviews the types of map icons and elements of icon design, including the ways in which the visual variables are used in map icon communication. As communicative devices, icons are imbued with cultural meanings and can oftentimes lead to the preservation of stereotypes. This review concludes with an examination of icons’ perpetuation of – and challenge to – cultural stereotypes.

CV-30 - Map Production and Management

Map production describes the experience of managing the many aspects and details of map creation. Often the map product is created for someone else—a client, supervisor, or instructor. Describing the intention of the map and evaluating available resources ahead of the project can help the cartographer define content requirements, stay on task, and ultimately meet deadlines. The project management life cycle involves clear communication between the cartographer and client, with resolutions to common questions best addressed at the beginning of the project. The process then iteratively cycles through phases that include research and production, followed by quality control, and concludes with file preparation and delivery.

CV-06 - Map Projections

Map projection is the process of transforming angular (spherical / elliptical) coordinates into planar coordinates. All map projections introduce distortion (e.g., to areas, angles, distances) in the resulting planar coordinates. Understanding what, where, and how much distortion is introduced is an important consideration for spatial computations and visual interpretation of spatial patterns, as well as for general aesthetics of any map.

CP-15 - Mobile Devices

Mobile devices refer to a computing system intended to be used by hand, such as smartphones or tablet computers. Mobile devices more broadly refer to mobile sensors and other hardware that has been made for relatively easy transportability, including wearable fitness trackers. Mobile devices are particularly relevant to Geographic Information Systems and Technology (GIS&T) in that they house multiple locational sensors that were until recently very expensive and only accessible to highly trained professionals. Now, mobile devices serve an important role in computing platform infrastructure and are key tools for collecting information and disseminating information to, from, and among heterogeneous and spatially dispersed audiences and devices. Due to the miniaturization and the decrease in the cost of computing capabilities, there has been widespread social uptake of mobile devices, making them ubiquitous. Mobile devices are embedded in Geographic Information Science (GIScience) meaning GIScience is increasingly permeating lived experiences and influencing social norms through the use of mobile devices. In this entry, locational sensors are described, with computational considerations specifically for mobile computing. Mobile app development is described in terms of key considerations for native versus cross-platform development. Finally, mobile devices are contextualized within computational infrastructure, addressing backend and frontend considerations.

CV-40 - Mobile Maps and Responsive Design

Geographic information increasingly is produced and consumed on mobile devices. The rise of mobile mapping is challenging traditional design conventions in research, industry, and education, and cartographers and GIScientists now need to accommodate this mobile context. This entry introduces emerging design considerations for mobile maps. First, the technical enablements and constraints that make mobile devices unique are described, including Global Positioning System (GPS) receivers and other sensors, reduced screensize and resolution, reduced processing power and memory capacity, less reliable data connectivity, reduced bandwidth, and physical mobility through variable environmental conditions. Scholarly influences on mobile mapping also are reviewed, including location-based services, adaptive cartography, volunteered geographic information, and locational privacy. Next, two strategies for creating mobile maps are introduced—mobile apps installed onto mobile operating systems versus responsive web maps that work on mobile and nonmobile devices—and core concepts of responsive web design are reviewed, including fluid grids, media queries, breakpoints, and frameworks. Finally, emerging design recommendations for mobile maps are summarized, with representation design adaptations needed to account for reduced screensizes and bandwidth and interaction design adaptations needed to account for multi-touch interaction and post-WIMP interfaces.

AM-44 - Modelling Accessibility

Modelling accessibility involves combining ideas about destinations, distance, time, and impedances to measure the relative difficulty an individual or aggregate region faces when attempting to reach a facility, service, or resource. In its simplest form, modelling accessibility is about quantifying movement opportunity. Crucial to modelling accessibility is the calculation of the distance, time, or cost distance between two (or more) locations, which is an operation that geographic information systems (GIS) have been designed to accomplish. Measures and models of accessibility thus draw heavily on the algorithms embedded in a GIS and represent one of the key applied areas of GIS&T.

KE-34 - Multi-Organizational GIS Coordination

For many years, collaboration has been a key cornerstone in the success of efforts achieved by the geospatial community.  When paired with governance, collaborative efforts often lead to sustainability and have the effect of broadening the benefits that can be achieved.  The following text shares how the geospatial community uses collaboration and governance as tools to achieve benefits across the community.  Case studies are provided to illustrate the process and the outcomes achieved. 

CV-12 - Multivariate Mapping

Bivariate and multivariate maps encode two or more data variables concurrently into a single symbolization mechanism. Their purpose is to reveal and communicate relationships between the variables that might not otherwise be apparent via a standard single-variable technique. These maps are inherently more complex, though offer a novel means of visualizing the nuances that may exist between the mapped variables. As information-dense visual products, they can require considerable effort on behalf of the map reader, though a thoughtfully-designed map and legend can be an interesting opportunity to effectively convey a comparative dimension.

This chapter describes some of the key types of bivariate and multivariate maps, walks through some of the rationale for various techniques, and encourages the reader to take an informed, balanced approach to map design weighing information density and visual complexity. Some alternatives to bivariate and multivariate mapping are provided, and their relative merits are discussed.

DC-16 - Nature of Multispectral Image Data

A multispectral image comprises a set of co-registered images, each of which captures the spatially varying brightness of a scene in a specific spectral band, or electromagnetic wavelength region. An image is structured as a raster, or grid, of pixels. Multispectral images are used as a visual backdrop for other GIS layers, to provide information that is manually interpreted from images, or to generate automatically-derived thematic layers, for example through classification. The scale of multispectral images has spatial, spectral, radiometric and temporal components. Each component of scale has two aspects, extent (or coverage), and grain (or resolution). The brightness variations of an image are determined by factors that include (1) illumination variations and effects of the atmosphere, (2) spectral properties of materials in the scene (particularly reflectance, but also, depending on the wavelength, emittance), (3) spectral bands of the sensor, and (4) display options, such as the contrast stretch, which affect the visualization of the image. This topic review focuses primarily on optical remote sensing in the visible, near infrared and shortwave infrared parts of the electromagnetic spectrum, with an emphasis on satellite imagery.  

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