Google Earth and a 5 minutes book review: Geology Illustrated

A few years ago I bought on e-bay Geology Illustrated – by John S. Shelton, for just 10 US dollars. Every time I look at, and inside the book I can’t but think those were the best 10 dollars I ever invested in books.

There are already reviews and plenty of praise for this book out there – no need to repeat any of that if not briefly. My take is that the geology is clear and well explained. A bit simple, but simple is not always bad. And Shelton himself in the preface recommends this book as a “point of departure rather than something to lean on…” but that is perfect if you are a teacher looking for material, a first year college student, or a non-geologist looking for a high quality introduction.

But the photographs are priceless, and Shelton, who was also a pilot, took them all himself. Again, the author reminds us that nothing can replace field experience, and having  been trained as a field geologist (an average one, but that’s another story) I cannot but agree. However, lacking access or time to go to the field, or both, I find looking at a book like this can be an extraordinary substitute. That is especially true if you combine the reading with using Google Earth (particularly if you are a visual-spatial learner) and that is exactly what I did.

I already praised Google Earth for visualisation in this post. This program is a fantastic tool for learning geology, and today, to reinforce the point, I want to show you a couple of examples of Google Earth views replicating almost exactly figures from Chapter 14 of Geology Illustrated: The works of streams and rivers.

The first view is a replica of Figure 130 in the book, showing a fantastic example of a stream (the Colorado River) deepening its valley at the Marble Canyon.

The second view is a replica of Figure 135, showing many excellent examples of stream capture by headward erosion. Notice that in the 60s, when the photo was taken by Shelton, the highway (US Highway 101 north of San Juan Capistrano, California) was the only visible evidence of human activity.

The last view is a replica of Figure 137 in the book, showing the meander belt of the Animas River a few miles from Durango, Colorado. Looking at this was by far my favourite as it gave me the opportunity to create my own time lapse: a repeat snapshots of the same landscape nearly 50 years apart. Tis is priceless: 50 years are nothing in geological time scale, and yet there are already some significant differences in the two images. For example, it looks like the meander cutoff  in the lower left portion of the image had ‘just’ happened in the 60s, whereas at the time the imagery used by Google Earth was acquired (I imagine in the last few years), the remnant oxbow lake is more clearly defined. Another oxbow lake in the center has nearly disappeared.

I found that this process of looking for and replicating the photos in the book, zooming in and out, then in again changing view was a fantastic way to see the geological features as part of the larger geological context, visualize them, see the interconnection with other elements of the landscape, observe how erosion and deposition, and human processes have modeled the landscape in just a few decades (as in the second and third examples).  As a geophysicist, sitting in the office away from the outcrops, this is  invaluable, and a great aid in finding analogs in support of seismic interpretations. And really you don’t need a book in your lap to start the process.

In a future post I will show my results at creating similar views using HD lidar data, which can be downloaded from the National Center for Airborne Laser Mapping, as done in this blog post on Quest.


John Shelton’s obituary, August 2008

Geomorphology from space

Digital cartography picks

My top pick is NASA’s new integration of the Apollo Zone Digital data. It was done at Ames Research Centre thanks to a newly developed software system for orbital imagery. The software allows fully automated image mosaicking and terrain modeling of data taken from different positions, with different exposure and resolution, and even selects best image when multiple coverage exists. You can read about this exiting new development in the article Powerful Pixels: Mapping the “Apollo Zone” which has links to the open source software libraries Ames Stereo PipelineNeo-Geography Toolkit and NASA Vision Workbench. You can click here to download a kml file for viewing the image mosaic and digital elevation model in Google Earth. I tried it out and it looks great. Check these screen captures below:

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Image processing tips for geoscientists – 1

Today I would like to show a way to quickly create a pseudo-3D display from this map:

Original image

The map is a screen capture of a meandering river near Galena, Alaska, taken in Google Earth. I love this image; it is one of my favorite maps for several reasons. First of all it is just plainly and simply a stunningly beautiful image. Secondly, and more practically, the meanders look not too dissimilar to what they would appear on a 3D seismic time slice displayed in grayscale density which is great because it is difficult to get good 3D seismic examples to work with. Finally, this is a good test image from the filtering standpoint as it has a number of linear and curved features of different sizes, scales, and orientation.The method I will use to enhance the display is the shift and subtract operation illustrated in The Scientist and Engineer’s Guide to Digital Signal Processing along with other 3×3 edge modification methods. The idea is quite simple, and yet extremely effective – we convolve the input image with a filter like this one:

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Time to spice up your visualization skills?


I love a visualization well done, whether by me or someone else. In fact, I love visualization period. I find there’s always something to learn by looking at an image or animation, and always look for something new and interesting I can learn.

Today I would like to share with readers some of the things I learned, saw, or admired over time.

Where to start? Visualization in Google Earth

Yes, we all know nowadays how to use Google Earth to plan our next vacation, check our old neighbor’s new house, etcetera. But visualization? Yes indeed. Just today I was at a roundtable meeting of Fig Tree members (Fig Tree is an NGO that supports international development projects) and I learned how Google Earth is used by many NGOs for project planning: for a start check the Mercy Corps‘ Rough Google Earth Guide, these map overlay tools, and the official gallery.

Here’s a tutorial on annotating Google Earth:

and some beautiful visualizations created using Matlab in conjunction with Google Earth.

Read a book, pick a course

There are scores of great books on visualization. I introduce two I really like in my more recent post Two great visualization books. Reader Ron DeSpain mentioned these free online courses in a comment:  Introduction to Infographics and Data Visualization, by Roberto Cairo, which is also the author of  The functional art, a blog and a book, and Information Visualization MOOC, by Katy Börner and colleagues at the University of Indiana.

Be a generalist and a specialist at the same time

Specialize in one discipline if you can. See what the experts in that field do. For example I am a Geophysicist and do a lot of seismic visualization and interpretation, so I look at what folks like Steve Lynch, or Art Barnes to name a couple, and follow Agile Geoscience blog. Again, keep abreast of the latest technology: Google Earth is increasingly being used in seismic exploration planning and visualization. You can find some examples here and even get some seismic overlays and display them yourself: if you have Google Earth just download this KMZ file and double-click.

I am also always curious about other fields and browse for examples incessantly. I am interested in music, and I was thrilled to find this great review of Music Visualization. I am also interested in Astronomy and Planetary Exploration, and over time I have found some amazing visualizations.  This video for instance is a volume rendered animation of the star-forming region L1448 created by Nick Holliman (Durham University) in VolView, an open source volume visualization program.

Credits: Harvard Astronomical Medicine Project

Just recently I found on Visurus a time-lapse (1950 -2011) geocentric map of the visible universe.

A while back I learned a lot on from books like A Beginner’s Guide to Constructing the Universe, and its exploration of the relationships between nature, art, science, symbols, and numbers; I regularly go back to it.

Look for synergies and collaborations. Here’s what can happen when you put together a geologist and a design expert:

Don’t be afraid of using social media

Check answers on sites like Quora or Stack Overflow. Check regularly or better subscribe to visualization or specialistic blogs: I mentioned already VizThink and Fell in Love with Data.  I also like the excellent and FlowingData, where you can actually find an extensive list of blogs.

Study what others do

Take a look at the groundbreaking work of Hans Roslins with his Gapminder:

Check this video on Designing for Visual Efficiency from Vizthink to learn how to declutter your visualizations:

Ignite Toronto 2: Ryan Coleman – Designing for visual efficiency at Ignite Toronto on Vimeo.

and this one on  Journalism in the age of data:

Journalism in the Age of Data from Geoff McGhee on Vimeo.

Looking for ideas?

Here’s an interesting visualization project from IMB: sign up on Many Eyes to not only browse several examples of visualizations but also to upload your own data and outsource the visualization project.

Color, color, color!

A subject I think is particularly important is how to use color in your presentations and visualizations. Use color sparingly and sensibly, and ad hoc. Know about color deficiencies and confusing color schemes and the difference a perceptually appropriate colormap can do. With Vischeck, Color Oracle, and Dichromacy you can simulate how people with different color vision deficiencies will see your images and decide if you need a different colormap; for two color contrast for presentations, webpages, diagrams, use the Accessibility Color Wheel. Select colormaps according to task, and avoid artifacts when using color blending. Reduce the hue range when possible and choose it based on the concept of color harmonization. After all, the hue circle isn’t really circular at all and contains non-spectral colors (purple). You can design harmonious schemes with Color Wheel Pro, and check the palettes’ mood using Colour monitor, a wonderful tool by Richard Weeler. Avoid at all costs rainbow and similar color palettes.

Finally, A fantastic resource on color: References and Resources for Visualization Professionals by by Robert Simmon at NASA’s Earth Observatory

Deep Zoom technology

Thanks to this technology you can now build interactive applications with seamless dynamic zooming. Look at Steve Lynch’s seismic visualization built using MS Silverlight, and Well Visualization in Prezi by Evan Bianco.

Regularly remind yourself to go back to the basics

The best tools are your brain and your hand. Draw and sketch a lot. Concept maps are a great tool for brainstorming and tinkering with ideas, whether on paper or your computer; check NASA’s Mars Exploration Concept Map. Finally, I strongly encourage you to read Experiences in Visual Thinking.

Want to make it your profession?

Read The Data Visualization Beginner’s Toolkit series from Fell in Love with Data blog. This is the introduction to the series. In the first post he reviews books and other resources. In the second post he introduces some rules and more importantly the software tools. There’s a  feature interview with Moritz Stefaner on data visualization freelancing:

Interview: Moritz Stefaner on Data Visualization Freelancing from FILWD on Vimeo.

And  if you are intimidated by having to pick up programming skills, he has a post that is just right for you.

Post Scriptum

It should go without saying, but unfortunately it does not: if data are sensitive, don’t forget about privacy.

Resources and tools

visualisingdata’s  essential collection of visualisation resources

Visualization Tools & Resources

How to avoid equidistant HSV colors

Non-uniform gradient creator

Colormap tool

Color Oracle – color vision deficiency simulation – stand alone (Window, Mac and Linux)

Dichromacy –  color vision deficiency simulation – open source plugin for ImageJ

Vischeck – color vision deficiency simulation – plugin for ImageJ and Photoshop (Windows and Linux)