Joshua Stevens

Eikon: A Library of The Saints

Wed, 21 Oct 2026 16:31:09 -0400

Maps are one of my core passions. But I also have a deep interest in art, history, and the church. In my spare time I’ve been tinkering with an idea to build an interactive, searchable library of iconography. Some recent downtime provided just the right opportunity to bring it to life.

Still Bivariate, Still Curious

Sat, 17 Oct 2026 09:00:00 -0400

Eleven years ago I wrote a how-to guide for bivariate choropleth maps, prompted by a quip I overheard at NACIS: “I’m not bivariate, but I am curious.” Back then, making bivariate maps meant blending color schemes in graphics programs, hand-tuning the corner where both variables run high, and stitching two classifications together into a single attribute your software could understand. It worked in any tool, but it took some patience.

A lot has changed since then.

Introducing Phosphor

Wed, 23 Sep 2026 15:05:57 -0400

I am proud to release Phosphor, a new tool to make color for data visualization even easier.

Formatting Gratitude

Mon, 21 Sep 2026 00:00:00 +0000

“Don’t take the job,” he said.

Almost thirteen years have passed since my friend and mentor shared these words. He was the only dissenting voice among half a dozen professionals and friends whose opinions I sought. And it’s not those four words, but the rationale behind them, that has stuck with me the most.

Flashback to the brisk autumn of 2014. I had earned PhD candidacy the year before, passed comprehensive exams the previous semester, and my son was entering his sixth month of life on Earth. It was an exciting time—and it was about to get a lot more exciting.

Behind the Scenes of the Earth Observatory

Mon, 07 Mar 2022 00:00:00 -0500

Since 1999 NASA’s Earth Observatory has produced more than 12,000 data visualizations, images, and maps. To do so, we have adopted an approach that enables us to be both consumers and producers of science. In other words: we use science to inform how we communicate science.

Mapping Ukraine's Refugees

Mon, 07 Mar 2022 00:00:00 -0500

Disasters are the great catalysts of cartography. There is no stronger impetus for new maps than earthquakes, landslides, floods… and wars.

With new maps come new desires. The field of cartography has come a long way, and both its practitioners and students have learned a great deal. Myriad data sources are within an ever-closer grasp, and we’ve learned to approach each with more care, more diligence, and more responsibility.

2020 Top 10

Mon, 04 Jan 2021 08:47:22 -0500

The NASA Earth Observatory publishes a new image-driven article every day. This torrent of graphics is enhanced by coverage of breaking news, natural hazards, and periodic, deep-diving features. As a result, our team easily publishes more than 500 visuals each year.

Choosing the ten best from such list is no small task. And it inevitably leaves out numerous pieces that, to be honest, pains me to exclude. Nonetheless, ten it shall be.

The Red Planet

Thu, 02 Apr 2020 00:00:00 +0000

I am extremely pleased to release a new poster showcasing the topographic relief of Mars.

My days are usually filled with Earth. Satellite images, maps, data analysis… all originating from, or looking at, our blue planet. The third rock from the Sun.

Sometime last year I decided to figuratively leave Earth and see what’s going on with our skyward neighbor.

Pinewood Nerdy

Thu, 23 Jan 2020 06:31:26 -0500

I was not sure what to expect when my son wanted to sign up for cub scouts. But I knew, at some point, Pinewood Derby would come into the picture.

The moment came. He built a car. He raced it. And it was just as awesome as we had hoped. With so much creativity and hands-on crafting, followed by actual racing, it’s a tough experience to top.

Then I saw the data being recorded by the digital track. Now it was my turn to have some fun.

Tutorial: Turning on The Lights

Mon, 01 Apr 2019 09:55:02 -0400

The most familiar views of Earth from space feature a blue-green planet lit by the Sun.

But in the darkness of night when the Moon, city lights, fires, or aurorae illuminate Earth, some satellites continue to gather images of light. And they are fantastic!

So how does such imagery come to be? Let’s take a look!

Topographic Diversity of the Contiguous USA

Thu, 21 Mar 2019 12:19:38 -0400

While exploring data offered within Google Earth Engine (as I am wont to do), I came across a gorgeous and elegant layer from the U.S. Geological Survey.

This data, which represents “topographic diversity,” immediately conveys exactly what it aims to: topography. But the ridges and valleys are not representative of Earth’s bumpy surface alone.

3D Models from NASA

Sun, 03 Mar 2019 09:24:03 -0500

You’re probably well aware that NASA has launched numerous spacecraft—some destined for orbit, others to land on distant planets, and some to initiate a galactic handshake beyond our solar system.

Many of these missions have corresponding 3D models. What’s more, NASA has made a number of these available to the public. From satellites and shuttles to rovers and crew modules, more than 300 objects are currently available to download.

Mapping the Distance to the Nearest Coastline

Tue, 12 Feb 2019 19:50:03 -0500

Recently, I stumbled upon a NASA dataset containing the distance to the nearest coastline. The data are a rather straightforward calculation based on input from GSHHG—the Global Self-consistent, Hierarchical, High-resolution Geography Database.

Provided as a convenient GeoTIFF, the coastline distances are available in 0.04° and 0.01° resolutions. This makes it ideal for quick exploration. Or a dive down geographic rabbit holes.

Glen Canyon National Recreation Area

Sun, 27 Jan 2019 09:41:58 -0500

One of my favorite places to see in imagery and maps is Glen Canyon National Recreation Area and The Rincon. Here, water meets stone as myriad canyons reach out from the serpentine courses of the Colorado and Escalante Rivers.

Tactile Topography

Wed, 23 Jan 2019 12:33:53 -0500

There’s something special about topographic maps. Each is different than the next, yet many reflect a canvas replete with smooth contours, pleasing colors, and a technical accuracy that can send both the mind and feet wandering.

It is hard to imagine improving the natural aesthetic that topographic maps tend to convey.

Graveyards of The Contiguous USA

Sun, 28 Oct 2018 18:24:44 -0400

Lately I have been challenging myself to read more fiction. The most recent book to be checked off my list is Stephen King’s Pet Sematary. A morbid and suffocatingly dark story, and one I had previously only known from seeing the 1989 film as a kid. (Yes, the book is better. By a long shot!)

Commanding Cartography

Wed, 17 Oct 2018 13:03:32 -0400

Compelling cartography has never been easier or more abundant. We are inundated with new tools and technologies. All the while, one of the most powerful assets in the cartographer’s arsenal is being overlooked: the command line. Using keystrokes to create maps might sound like a task of yesteryear, but I am here to tell you it is a wormhole to the future. Whether you design maps for national parks or newsrooms, the terminal will enable you to supercharge your workflows with speed and elegance. This talk introduced some old tricks and new tools for designers on any deadline.

Landsat Fact Meets Fiction in Kong: Skull Island

Sun, 04 Feb 2018 08:08:46 -0500

In Kong: Skull Island, we follow a crew of scientists and military specialists into the thick jungles of an uncharted Pacific island. Encounters with previously unknown creatures abound. Released in 2017, the film is set in 1973 and prominently features a fictional company—Landsat—whose work involves classified satellite data.

But is it all fiction?

Now on Hugo

Mon, 16 Oct 2017 20:50:23 -0400

A few years ago I made the move from Wordpress to static pages. The benefits were immediate, and it has been nice not worrying about plugins, security patches, or millions of updates since.

Bivariate Choropleth Maps: A How-to Guide

Wed, 18 Feb 2015 00:00:00 +0000

“I’m not bivariate, but I am curious.” That quip has been stuck in my mind ever since I overheard it at the 2013 NACIS conference in Greenville, SC. Not only was it perfectly timed after a talk about bivariate mapping, but it rang with a great deal of truth: a lot of folks aren’t creating bivariate maps, but they want to try. While it was just a joke and the person who made it can easily create bivariate maps, most people find them too difficult or mysterious.

That’s a real shame because bivariate choropleth maps are incredibly useful and very easy to make. So let’s go ahead and make one!

The Ebb and Flow of Polar Sea Ice

Sun, 08 Feb 2015 00:00:00 +0000

In some very real ways, polar sea ice is the backbone of our planet’s climate. When more ice is present, its bright surface tends to reflect sunlight, cooling things down. When there is less white, snow-covered ice, the ocean’s surface becomes a bit darker. A darker ocean surface absorbs more sunlight, causing it to warm. The relationships between climate and ice are much more complicated than that, as the thickness of the ice also influences a variety of subsurface feedback loops that have long-term effects.

HDRI Lighting for Shaded Relief Maps

Fri, 08 Aug 2014 00:00:00 +0000

Shaded relief maps are among my favorite of all map types. Not only do they form the foundation for many other maps and derivative layers, they present a fascinating challenge: depicting an abstraction of terrain in a natural way while balancing accuracy with aesthetics.

This push and pull between modeling a natural phenomenon (the illumination of Earth and the shadows cast by the sun) with artistic purposes has captivated cartographers for centuries. It’s no surprise that as technology advanced, so too did the modeling of the sun’s rays. With this in mind, I wondered how techniques in 3D ray tracing carry over to shaded relief mapping.

Open Source Copyright Infringement: Are DMCA Takedowns on GitHub Increasing?

Mon, 07 Jul 2014 00:00:00 +0000

While browsing /r/linux I saw this post: Rate of DMCA takedown demands is increasing on GitHub.

That sounds pretty scary, for a couple of reasons. On one hand, it could mean that companies are really dropping the hammer and coming after folks more often and potentially in error. On the other, it could mean the open source community is becoming more lax or lazy, using others’ code without respecting licenses or copyright.

But could there be a third alternative? Is the rate of DMCA takedowns really increasing in a meaningful way?

Fortunately GitHub is open about the DMCA notices they receive. Since January 27, 2011 GitHub has posted each request received and each counter-notice issued. All 317 of them.

Visual Guide to Painful Hymenopteran Stings

Fri, 27 Jun 2014 00:00:00 +0000

For most of us, insect stings are a thing to avoid. That’s not the case for entomologist Justin O. Schmidt. That’s because Dr. Schmidt has dedicated his life to studying venomous hymenopterans, the order of insects made up of ants, bees, and wasps. Through his research, he has been stung countless times. As a result, he developed the Schmidt Sting Pain Index.

I stumbled upon Schmidt’s work after seeing this video of warrior wasps. One of the noteworthy characteristics of warrior wasps is that when threatened, they rhythmically flap their wings against their bodies in perfect synchrony, producing a sound not unlike marching soldiers. The other characteristic these wasps are known for is a sting that hurts!

Just how much does a sting from a warrior wasp hurt?

Moving from WordPress to Middleman

Wed, 18 Jun 2014 00:00:00 +0000

Note: In September 2017 this site was rebuilt with Hugo. The text below no longer describes my own site, but I would still use Middleman (or any other static generator) over WordPress.

Recently I’ve spent a few evenings removing WordPress and rebuilding this site on top of Middleman. The new site is still a work in progress and I have more features to add, but all of the previous content has been brought over. It should be safe to launch this.

So why did I do it? Over the past two years I’ve become increasingly frustrated with WordPress. Despite serving compressed pages, caching data, and reducing unnecessary scripts, page load times seemed to increase with each new version. Some of my more popular pages were averaging 5 seconds to load. That’s ridiculous.

Even when WordPress itself performed well, it required additional plugins just to have reasonable features (e.g., caching, contact forms, spam protection, SEO optimization, etc.). Each of these requires constant updates, and one can never be sure if updating one plugin is going to break other plugins, or worse, the entire site. Compatibility reports from other users are helpful, but are often incomplete. Logging in just to write a simple post became a chore: update this, double check that, fix this other thing that the previous update broke, and so on. Long story short, it got old.

The Many Birthplaces of Memorial Day

Tue, 27 May 2014 00:00:00 +0000

Yesterday was Memorial Day. Like many other Americans, my family and I spent this day of national remembrance at a local park. We made the short trip to historic Boalsburg. Those in the know will recognize that Memorial Day in Boalsburg, PA is no ordinary affair. It is a massive celebration. This was especially true this year, which marks the 150th Memorial Day celebrated in Boalsburg. Thousands of people from all over gathered to honor our veterans who gave the ultimate sacrifice. What started as a time to decorate graves with flowers has now grown into a large festival, with celebratory events found at every corner of the township.

It was also a learning opportunity. Almost everyone knows about Pennsylvania’s vital role in the Civil War and the importance of Memorial Day in the region. As a Michigan native, what I didn’t know was that Boalsburg itself was the very birthplace of Memorial Day.

Or at least it claims to be.

The Map of GDELT Predictions in Afghanistan as You Should Have Seen It

Mon, 21 Oct 2013 00:00:00 +0000

For the last several weeks, I’ve been creating a visualization of past and predicted conflicts in Afghanistan. The data, which come from a statistical model developed by Jay Yonamine with help from John Beieler, show us what might happen based on a long history of what has happened. The database behind this model is known as GDELT, or the Global Database of Events, Language, and Tone. GDELT has received a lot of attention lately and I’ve participated in two hackathons that have emerged around it. After Wired showed interest in publishing this story along with the visualization, I was thrilled.

'Squatch Watch: 92 Years of Bigfoot Sightings in the US and Canada

Tue, 17 Sep 2013 00:00:00 +0000

Every now and then a dataset comes along that just has to be mapped. This is one of those times.

Bigfoot. Sasquatch. Skookum. Yahoo. Whatever you call it, the towering man-like ape is a folklore staple. From stories of Yeti in the Himalayas to Wildmen in the Pacific Northwest, people have been talking about and trying to find the creature for ages. Occasionally, some form of evidence – like Patterson’s famous 1967 film – emerges and either feeds our fascination or gets dismissed as a hoax. In either case, it’s easy to see why believers search for proof and skeptics remain doubtful.

Through archival work and reports submitted directly to their website, the Bigfoot Field Researchers Organization has amassed a database of thousands of sasquatch sightings. Each report is geocoded and timestamped. Occasionally, even photos and videos of the alleged evidence are included. I’m not quite sure how I stumbled across this, but I’m glad I did.

After crawling the data and converting it to a more convenient format, I mapped and graphed all 3,313 sightings that were reported from 1921 to 2013:

Your Favorite Traffic Map is Lying to You

Fri, 28 Jun 2013 00:00:00 +0000

Traffic maps are among the most widely used maps available today. Whether they are accessed through a web browser, an app on your smartphone, or an in-vehicle navigation system, many popular maps include a traffic layer – and for good reason. The proliferation of live traffic information is extremely beneficial. With real-time congestion data we can avoid delays, plan better routes, and get to the places we need to be when we need to be there. Traffic maps simplify this process and clarify the costs and benefits associated with various routes.

Or so many think.

Big Data Social Science Video Demo: SensePlace2

Mon, 27 May 2013 00:00:00 +0000

This year I was selected to represent the 2013 Big Data Social Science IGERT in the annual poster and video competition hosted by the National Science Foundation. The news came as both an honor and a challenge.

Big Data Week: Geographic Visualization and a Demo of CartoDB

Fri, 26 Apr 2013 00:00:00 +0000

Spatial is special. Accordingly, there are many considerations that need to be made prior to and during the task of visualizing spatial data. Chief among these considerations are your goals and what it is you’re actually trying to accomplish with a map. Are you communicating results you’ve already found? Enabling users to explore the data to discover information on their own, possibly generating new hypotheses?

Accommodating Big Data in Visual Analytics

Wed, 17 Apr 2013 00:00:00 +0000

Last week I had a blast visiting Santa Barbara and Los Angeles. While I enjoyed the wineries and sunshine, the annual meeting of the Association of American Geographers was the highlight of the trip. With so many talks on cartography, GIS, and cyber science, it was my favorite AAG conference yet.

What made AAG even more enjoyable was the acknowledgement of big data within GIS (though I’d argue we’ve all been doing “big data” for decades now).

Big Data Social Science Poster Session

Tue, 12 Feb 2013 00:00:00 +0000

As part of the NSF IGERT in Big Data Social Science, Pond Lab hosted a public poster session this afternoon.

A total of eleven different posters were presented, covering topics in big data that ranged from text processing and visualizing uncertainty to computing voter sentiment and analyzing data of patients’ heart rates.

I presented work on a GeoVISTA project that leverages geovisual analytics and Twitter to help users make sense of the spatiotemporal variation of place and topic mentions within hundreds of millions of tweets.

Mapping Tools – Analysis and Visualization of Spatial Data

Fri, 11 Jan 2013 00:00:00 +0000

I had the pleasure of being invited to talk about mapping tools at the Hacking Science Hands on Sessions, led by professor and tech enthusiast Marcel Salathé.

“Mapping tools” is a pretty broad topic and it’s impossible to cover the whole scope of cartography, GIScience, and the suite of existing software in a single hour. So I took attendants on a whirlwind tour of tools, both open source and not, highlighting the strengths and weaknesses of each.