The Pleasure of Finding Things Out: A blog by James Triveri
OpenStreetMap (OSM) is a collaborative project that creates a free, editable map of the world. It’s built and maintained by a global community of contributors who collect and upload geographic data including roads, buildings, parks and more, using GPS devices other public sources. OSM allows...
The Pleasure of Finding Things Out: A blog by James Triveri
ZIP Codes are widely used in analytics because they serve as a convenient proxy for geographic location, even though they are not true areal units. In the United States, ZIP Codes are created and managed by the United States Postal Service for the purpose of delivering mail. They represent...
The Pleasure of Finding Things Out: A blog by James Triveri
TimestampedGeoJson is a Folium plugin that facilitates the visualization of geospatial data that evolves over time using the GeoJSON format with timestamps. This is useful for tracking vehicle trajectories, satellites, pedestrian traffic, changes in weather patterns or any other geospatial...
The Pleasure of Finding Things Out: A blog by James Triveri
I recently became interested in geohashing and wanted to develop an understanding of the algorithm with the aim of implementing it myself. I was surprised to find it to be quite simple and intuitive. In this article, I’ll demonstrate how to generate geohashes for a given latitude and longitude and...
The Pleasure of Finding Things Out: A blog by James Triveri
I’ve been spending time exploring Ningchuan Xiao’s excellent book, GIS Algorithms. This text offers a comprehensive dive into fundamental geospatial concepts including geometric algorithms, spatial indexing, and spatial analysis. The author thoroughly explains the theoretical foundations of each...
The Pleasure of Finding Things Out: A blog by James Triveri
Spatial autocorrelation is a statistical concept that measures how similar values of a variable are based on their proximity to each other on a map. Positive spatial autocorrelation means that geographically nearby values of a variable tend to be similar on a map: high values tend to be located...
Dr JTS
A previous post introduced a new algorithm in the JTS Topology Suite called RelateNG. It computes topological relationships between geometries using the Dimensionally-Extended 9 Intersection Model (DE-9IM) model. This algorithm is fundamental to a large proportion of spatial queries executed in...
Dr JTS
The most fundamental and widely-used operations in the JTS Topology Suite are the ones that evaluate topological relationships between geometries. JTS implements the Dimensionally-Extended 9 Intersection Model (DE-9IM), as defined in the OGC Simple Features specification, in the RelateOp...
Dr JTS
Recently a GEOS patch was contributed to change the KdTree query implementation to use an explicit stack rather than recursion. This has been ported to JTS as PR #779 (along with some refactoring).The change was motivated by a QGIS issue in which a union of some large polygons caused a stack...