Styling Lines with CartoCSS

A short example of CartoCSS class-based line rendering. CartoCSS is everywhere it seems. Well, it’s in Mapbox Studio and CartoDB, as well as whatever hand rolled option you choose. (However it is not geoserver CSS, though it looks somewhat similar). I used CartoCSS to render the below image. It’s a nordic ski map and has a […]

Scale in a Time of Web Maps

Scale has taken on a completely new meaning for me. In my training and early career, scale referred to a conversion measurement indicating a comparison between a measurement on a paper map and a measurement in the real world. The big ‘thing’ about GIS was that it was scale-less; you could zoom in as much […]

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 […]

Beware the Echo Chamber

There is a concept of spatial auto-correlation in GIS (Geographic Information Systems). This is a measure of the degree to which a set of spatial features and their associated data values tend to be clustered together in space (reference). So in small words: similar things tend to hang out together. This is often true of […]

Better Web Maps with Map Analytics

Analytics are a great tool for monitoring and reporting on website traffic and user interactions. It is reasonablely expected that, as a web developer I will use analytics to better understand my users and deliver them with incrementally improving services and experiences. At Sparkgeo we build web maps. We have been doing this for half a […]

Build a Better Map with Analytics [Video]

Dustin Sampson (@gridcell), one of our geospatial developers presented the core ideas behind tracking slippy map analytics at FOSS4G in September (2014, Portland). Check out his presentation here >>> Presentation Description Google Analytics is a great tool for monitoring and reporting on website traffic and user interactions but what it doesnt tell you is that […]

Mapping Exif Files

This is a quick note on how to map images in a directory purely from their exif files. An exif file is one which contains the meta data of the image. If the image was taken by a phone of GPS enabled camera, then a location will also be contained within that file. To read […]

Encoding GeoJSON Geometry

GeoJSON is a great format, easy to read/view/use but one thing that really stands out is the verbosity of numbers and its effects on file size.  Yeah in rare cases it “may” be needed but I’m pretty sure a length that is precise to, well less than a millimeter (example: stream length: 6849.41980435 meters) is […]

Step Up Your Raster Handling Skills

It is not uncommon for raster data to be large and unruly. Creating tiles is one way to deal with these large datasets and speed up rendering. This post introduces a few handy tools for dealing with raster data while walking through the process of combining multiple raster files to create tiles for a super-overlay […]