postgis

More to Maps than Markers

Google Maps have been with us since February 2005, virtually a decade ago as I write this (expect a party on Feb 8th 2015). From their acquisitions of Where 2 Technologies and Keyhole, Google ignited a cartographic web revolution. Yes, of course there were maps on the internet pre-Google Maps, but Google brought the web […]

Dissecting a Web Mapping Application

When talking with clients there is always a turning point in my mind where their request turns from being a “Google Map” to being a “web mapping application”. It is usually where data is being filtered, updataed, or when ‘users’ are mentioned. This a pivotal point where the project both gets more interesting, a lot […]

Building a US Census Tracts PostGIS Database

This article shows how you (yes, you!) can build your very own US Census Tracts PostGIS database. I had looked over the interwebs for some time under the false assumption that someone, somewhere would have already done this, but it seems not. So this article documents my process. I am running a mac, so some […]

Python Geospatial Development Published

Will Cadell was recently a technical reviewer on the latest edition of Python Geospatial Development. Go check it out on amazon here   Here’s the brief:   Geospatial development links your data to places on the Earth’s surface. Writing geospatial programs involves tasks such as grouping data by location, storing and analyzing large amounts of […]

ogr2ogr 3D Shapefile Import to PostGIS Tip

A very quick tip for those scratching their heads over trying to import a 3D shapefile (which doesn’t actually have any 3D data, or at least none you care about) into a flat (2D) PostGIS data set and you keep getting a geometry constratint error.  with a command like: ogr2ogr -update -append -f PostgreSQL PG:”dbname=postGISdatbase” […]

Using Prepared Geometries in Shapely

Shapely is a great tool for the geospatial developer. With Shapely it is possible to run PostGIS-like operations on non-PostGIS geometries. This can keep your python code looking smooth and consistent. In my experience it can also go rocket fast in certain applications. One of those applications is where you are using the same geometry […]

Sparkgeo and Google Maps

At sparkgeo we build next generation web mapping applications. That means we need to consider the mapping application from conception to delivery, from database to user expeirnce. Because we usually get to choose which mapping fabric we leverage, we will usually choose Google Maps. We use Google Maps for almost any public facing web mapping […]

PostGIS to PostGIS via ogr2ogr

OGR2OGR is a hugely useful GIS utility. Today I was using it to copy data between an Amazon Web Services (AWS) based PostGIS database and a local PostGIS database. This is a slightly weird use case, but I wanted to pull down some data locally for editing via Quantum GIS (QGIS). Here’s the command I used: […]