artlemboMar 14, 20193 minEasy bivariate map with PostgresA friend recently asked me about the cool looking bivariate maps produced with ArcOnline, lamenting that the capability seemed lacking in ArcGIS. Well, it ...
artlemboFeb 21, 20192 minEngaging students with multiuser editing, and FOSS4gA friend is doing some research on estrogen and estrodial in water samples in Delaware. We have about 50 sub-watersheds that show the upstream contributin...
artlemboOct 16, 20185 minBig Data ResultsI wanted to revisit the taxi data example that I previously blogged about. I had a 6GB file of 16 million taxi pickup locations and 260 taxi zones. I wante...
artlemboJul 7, 20182 minFinding “Dangles” with PostGISDo you have a set of lines that you need to determine if there are any “dangle” nodes? A dangle is a line segment that overhangs another line segment. Now,...
artlemboJun 22, 20181 minMulti-Ring (non-overlapping) Buffers with PostGISI was interested in creating mult-ring buffers but with a twist: I didn’t want the buffers to overlap one another. In other words, if I had concentric buffe...
artlemboDec 18, 20164 minUndergraduate Geospatial Python ProjectsGIS Programming students presented their programming projects to ESRI. First, I cannot say enough to thank ESRI for taking time out of their schedule to meet...
artlemboMay 26, 20162 minAdvanced Editing Capabilities with PostGISCLICK TO VIEW Jeff Scarmazzi presenting on h0w to create editing rules and triggers using Postgres and PostGIS Today I want to introduce you to another one o...
artlemboMay 18, 20163 minOpen Source GIS Course at UMD – the SyllabusUMD provided me with enrollment numbers, and we are getting a pretty full class. However, a few people on the “outside” have asked for a little more depth i...
artlemboApr 26, 20163 mink-Nearest Neighbor with PostGRESWell, even though you didn’t ask for it, I decided to create a k-nearest neighbor analysis in PostGRES/PostGIS. This has lots of potential: find the 5 neare...
artlemboApr 20, 20164 minTrade Area Analysis in Postgres / PostGISHow I used SQL to generate an accumulated sum of spatial data My friend Tomas does work with business analytics, and wanted to find a way to perform trade ar...
artlemboApr 19, 20162 minSQL and ogr to create 4D linesA friend recently asked me to help him generate polyline shapefiles with Z and M values that he could deliver to a customer. The problem was, the software h...
artlemboJul 7, 20152 minWhen More is Less…. lessons from processing large data filesMy good friend Stuart Hamilton gave me a fun conundrum to try out. He has a file of province boundaries (400 areas) and lidar derived mangrove locations (37 ...
artlemboJun 26, 20151 minNew Books – How do I do that in PostGIS, How do I do that in Manifold SQLI have two new books out – How do I do that in PostGIS, and How do I do that in Manifold SQL. From the back cover of How do I do that in PostGIS: For those w...
artlemboApr 20, 20154 minA Poor Man’s Parallel Processor for GISIn addition to SQL, I also am interested in processing large volumes of spatial data. One of the newest rages in “big data” is Hadoop. According to Wikiped...