Monitoring Environmental Changes with GIS Geographic Information Systems (GIS) are powerful tools for monitoring environmental changes over time. By leveraging spatial data and analysis capabilities, GIS enables tracking of forest loss, changes in water quality, identification of pollution sources, mapping of air quality and emissions, and assessment of climate change impacts. Tracking Deforestation and Habitat…
Understanding EPSG 4326 and 3857 EPSG 4326 – Geographic coordinate system using latitude and longitude EPSG 4326, also known as WGS 84, is a geographic coordinate reference system (CRS) that uses a latitude and longitude spatial grid to define two-dimensional positions on the Earth’s surface. Latitude measures north-south positions ranging from -90 to 90 degrees,…
Understanding Geographic Coordinates Latitude and Longitude Latitude and longitude are geographic coordinates that specify locations on the Earth’s surface. Latitude measures angular distance north or south from the equator, while longitude measures east-west angular distance from the prime meridian. Pairs of latitude and longitude coordinates pinpoint unique locations and are defined in reference to Earth’s…
Understanding Coordinate Reference Systems A coordinate reference system (CRS) allows locating geographical features on the Earth’s surface by defining a specific map projection, coordinate system, ellipsoid and datum. The coordinate values themselves only have meaning when linked to a well-defined CRS. The two most commonly used CRSs for web mapping are: EPSG 3857 – Based…
Understanding Shapefiles in QGIS A shapefile stores non-topological vector data for use in geographic information system (GIS) software. The shapefile format spatially describes vector features such as points, lines, and polygons representing buildings, roads, and boundaries. When loaded into QGIS Desktop, shapefiles allow users to visualize geographic data, view attribute information, edit geometries and data,…
Quantum Geographic Information System (QGIS) is a popular open-source geographic information system (GIS) application used to view, edit, and analyze geospatial data. When creating maps in QGIS that span the Pacific Ocean, it can be useful to center the map on the Pacific for optimal visualization and analysis. Centering maps over large water bodies like…
Defining the Problem: Imprecise Country Boundaries in Pacific Maps Precisely rendering country borders in geographic information system (GIS) software can be challenging, especially for Pacific island nations. Small errors in coordinate reference systems, extents, projections, symbology, and data resolution can cause misalignments between borders and coastlines, gaps between countries, or other spatial inaccuracies. For example,…
What’s Not Working With Cylindrical Projections in QGIS QGIS relies on the PROJ library for coordinate reference system transformations and map projections. While PROJ supports many different projections, its implementation of cylindrical projections has some key limitations that can lead to inaccuracies and errors in QGIS. Common Errors and Inaccuracies When adding layers or changing…
Visualizing Spatial Data The visualization of spatial data refers to the representation of information that has a geographic or positional component through digital maps and other graphical formats. Effective visualization of spatial data enables users to explore trends, patterns, and relationships in the data through an intuitive visual interface. Key considerations when visualizing spatial data…
Integrating heterogeneous geospatial data from diverse sources is a major challenge. Multiple vector and raster datasets often exist in different formats, coordinate systems, and with inconsistent attributes. Successfully fusing these disparate datasets into an interoperable geospatial data fabric requires leveraging various techniques and technologies. The Challenges of Data Interoperability A major barrier to integrating heterogeneous…