GIS Data, Spatial Analysis

The map shows age-adjusted colorectal cancer incidence and mortality rates per 100,000 population for Illinois residents by county and the locations of Federally Qualified Health Centers (FQHC). The purposes of the map are to identify areas with increased colorectal cancer incidence and mortality rates, educate the public and stakeholders on the burden of colorectal cancer in Illinois, and assist with future collaborative efforts toward reducing the burden of colorectal cancer among Illinois residents.

Overview of Public Health and GIS

This article provides an overview of the use of GIS as in public health. It includes a short history of its development as a tool in the field, explains how GIS is used, different data sources and how the privacy of sensitive health information is maintained. Examples of current research using GIS within the public health field are also provided.

Spatial Analysis

Predicting the post apocalyptic geography of zombies using fuzzy logic. Source: The Undead Liven Up the Classroom, Edward González-Tennant.

Overview of Fuzzy Logic Site Selection in GIS

Site selection is a type of GIS analysis that is used to determine the best site for something and fuzzy logic is one site selection method. It assigns membership values to locations that range from 0 to 1 and is commonly used to find ideal habitat for plants and animals. This article examines fuzzy logic and explains how and when to use it.

Spatial Analysis

Map showing results of site selection analysis. Red indicates areas with the highest matching criteria and blue shows areas that rank lowest in meeting all the criteria.

Overview of Weighted Site Selection and Suitability Analysis

Site selection is a type of analysis used in GIS to determine the best place or site for something. Weighted site selection analysis is one type of site selection that allows users to rank raster cells and assign a relative importance value to each layer. This article examines weighted site selection by explaining how it works and when it should be used. It also provides an example of a weighted site selection project for reference.

Spatial Analysis

Using a GIS-based “Least Cost Path Analysis” we investigated the connectivity among find locations along South Africa’s coast that are classified as Middle Stone Age. The methodology identifies the “cheapest” way to get from one point to another using the least amount of effort. We defined Pinnacle Point as the starting point for this analysis because it represents one of the oldest MSA find locations in South Africa. From there, routes to other known MSA find locations showing similar industries were calculated, concentrating on the coastal areas of South Africa. The criteria defining landscape resistivity is based on topographic information. For the cost layer, we classified the slope into four categories: 0-5°, 5-10°, 10-15° and >15°. The map shows the least cost-intensive ways to get from Pinnacle Point to the other find locations. The resulting pathways are influenced by the main geological structures such as the South African coastal mountain ranges that act as barriers. However, corridors can also be identified that indicate preferential pathways across these barriers, for example, by means of mountain passes. This preliminary analysis gives a first idea about the connectivity of MSA find locations. Map: M. Märker.

Overview of Least Cost Path Analysis

This article presents a summary of least cost path analysis, an important tool in GIS. Least cost path analysis is a distance analysis tool within GIS that uses the least cost path (the path between two locations that costs the least to those travelling along it) to determine the most cost-effective route between a source and destination. This article provides an overview of that topic as well as the requirements and steps for creating a least cost path analysis.

Spatial Analysis

Telecommunications Traffic Flow Map, 2000. Source: TeleGeography, Inc.

Overview of Flow Mapping

Flow maps are a type of map used in cartography to show the movement of objects between different areas on the Earth’s surface. This article provides a basic overview these maps, a description of how they work, describes the three different types of flow maps and explains the characteristics of a good flow map. For reference, it also several examples of different types of flow maps.

GIS Data

Click and drag the slider bar to compare these LDCM images, which zoom into the area around Fort Collins, Colo. On the left, the image is shown in natural color, created using data from OLI spectral bands 2 (blue), 3 (green), and 4 (red). The image on the right was created using data from OLI bands 3 (green), 5 (near infrared), and 7 (short wave infrared 2) displayed as blue, green and red, respectively. In the left-hand natural color image, the city's elongated Horsetooth Reservoir, a source of drinking water, lies west of the city. A dark wildfire burn scar from the Galena Fire is visible just to the left of the reservoir. The scar shows up bright, rusty red in the false color image.

Imagery and Its Use in GIS

Most imagery for use in GIS projects consist of satellite images or aerial photographs but it can also include, thermal images, digital elevation models (DEMs), scanned maps and land classification maps. This article examines imagery and how to effectively gather, store, process and interpret it for a variety of different GIS projects.

Spatial Analysis

Example of kriging: an interpolated surface based on data points.

Danie Krige and Kriging

Throughout his life, Daniel Gerhardus Krige (1919 – 2013) conducted much research into mining and mining engineering. His research led to the creation of the spatial interpolation method known as kriging. This article provides a biography of a Danie Krige, and presents a short overview of geostatistics and kriging.

Maps and Cartography

The Mercator projection. Source: USGS.

A Look at the Mercator Projection

Learn about the Mercator map projection – one of the most widely used and recently, most largely criticized projections. Amanda Briney takes a look at the history and development of the Mercator projection, how it works and some criticisms of the projection. The Mercator projection is just one of many map projections but it is one of the most recognizable.