DEEP DIVE

Better Compression of GIS Features

Replace JSON, XML and Shapefile Formats to Improve Your Visitor’s Experience

Compressing large datasets may be the difference between gaining and losing a potential user. (Image JH)

Telling data-intensive stories with online Geographic Information System (GIS) mapping tools requires careful planning. If we provide too little data, our story won’t have the impact it deserves. If we provide too much data, we risk losing impatient users who aren’t willing to wait the extra seconds needed to download large GIS files.

An important part of our work then, is ensuring that we package GIS data into its tightest possible form.

I’ve been working with global datasets to tell stories with an interactive orthographic projection of Earth. Here are some useful strategies for optimizing the time it takes to access large GIS files with web based visualization tools.

Baseline Case

As a case study, Natural Earth’s shapefile of the countries of the world is used (ne_10m_admin_0_countries). Here's what it contains:

• 258 features representing the outlines of countries and their outlying territories.
• 161 attributes for each feature: name, population, map color, etc.
• 474,443 longitude/latitude coordinate pairs.