When viewing a map or working with geospatial data, it is generally assumed to be accurate. But this may not always be the case, and many factors can affect accuracy. Unaccounted bias may be present, data may have been digitized at a coarser scale than was required, errors present on a previous dataset used to update a new one could be carried over, etc. So how accurate is a [...]
The first module of Special Topics in GIScience covers aspects of spatial data quality. Furthermore, the associated lab defines and contrasts the concepts of accuracy and precision in spatial data. Quality generally represents a lack of error, where error in spatial data is the difference between a true value and an observed or predicted value. Rather than unrealistically attempting to know the exact error, an estimated error based upon sampling or another statistical [...]
The final scenario for the lab of GIS Applications Module 6 is to determine a potential protected corridor linking two areas of black bear habitat in Arizona's Coronado National Forest. Data provided included the extent of the two existing areas of known black bear habitat, a DEM, a raster of land cover and a feature class of roads in the study area. Parameters required for a protected corridor facilitating [...]
The second half of Module 6 for GIS Applications conducts Least-Cost Path and Corridor Analysis on two scenarios. The first continues working with the Jackson County, Oregon datasets from Scenario 2. There are several ways that GIS measures distance. Euclidean, the simplest, represents travel across a straight line or "as the crow flies". Manhattan distance simulates navigating along a city street grid, where travel is restricted to either north-south [...]
Module 6 for GIS Applications includes four scenarios conducting Suitability and Least-Cost Path and Corridor analysis. Suitability Modeling identifies the most suitable locations based upon a set of criteria. Corridor analysis compiles an array of all the least-cost paths solutions from a single source to all cells within a study area. For a given scenario, suitability modeling commences with identifying criteria that defines the most suitable locations. Parameters specifying [...]
Module 5 for GIS Applications continues our focus on Hurricane Sandy and explores damage assessment for the storm's impact in the Garden State. Our first task was to create a formal hurricane track map showing the path Sandy took from the Caribbean Sea to the Northeastern U.S. The symbology uses custom color coded coordinate points showing the hierarchy of storm intensity. Included are the maximum sustained winds and the [...]
Module 4 for GIS Applications performs analyses on coastal flooding and storm surge. Storm surge is generally associated with landfalling tropical storms and hurricanes, but it can also be attributed to extratropical storms, such a Nor'easters along the Eastern Seaboard, or powerful winter storms with low barometric pressure and tight wind gradients. Coastal flooding events can also be due to spring tide events based upon the moon's cycle. The [...]
The course work for GIS Applications Module 3 looks further into 3D visualization, Line of Sight (LOS) analysis and Viewshed analysis with ArcGIS Pro. We are tasked with completing four exercises through ESRI training and read an article accessing the Lines of Torres Vedra, the defensive lines constructed to defend the Portuguese capital of Lisbon against Napoleon in 1810, with LOS analysis in GIS. Presentation of GIS data in [...]
Module 2 for GIS Applications returns us to take a more in depth look at the use of LiDAR, a topic briefly covered in previous courses. LiDAR (LIght Detection And Ranging) uses lasers, usually in the visible or near-infrared portion of the spectrum, calculates heights by measuring distances between a scanner and target area. The high energy pulses record the reflected response of different objects in a very narrow [...]
Our first topic in GIS Applications is crime analysis and the use of crime mapping for determining crime hotspots. Crime mapping techniques provide insight into the spatial and temporal distributions of crime. This benefits criminologists in the research community and professionals in law enforcement. Crime mapping factors in the importance of local geography as a reason for crime and considers that it may be as important as criminal motivation. [...]
