Author Archives: Christian Harder
Show me my home! The human era of GIS begins
Little more than a decade ago, seemingly the whole world snapped awake to the power of imagery of the earth from above. We began by exploring a continuous, multiscale image map of the world provided online by Google and other mapping companies. A combination of satellite and aerial photography, these pictures of Earth helped us to experience the power of imagery, and people everywhere began to experience some of what GIS practitioners already knew. We immediately zoomed in on our neighborhoods and saw locational contexts for where we reside in the world. This emerging capability allowed us to see our local communities and neighborhoods through a marvelous new microscope. Eventually, naturally, we focused beyond that first local exploration to see anywhere in the world. What resulted was a whole new way to experience and think about the world.
Initially, we zoomed in on our homes and explored our neighborhoods through this new lens. This experience transformed how people everywhere began to more fully understand their place in the world. We immediately visited other places that we knew about. Today, we continue by traveling to faraway places we want to visit. Aerial photos provide a new context from the sky and have forever changed our human perspective. This map tour visits selected areas in several communities where ultra-high-resolution imagery is available.
These simple pictures captured people’s imagination, providing whole new perspectives, and inspired new possibilities. Today, virtually anyone with Internet access can zero in on their own neighborhood to see their day-to-day world in entirely new ways. In addition, people everywhere truly appreciate the power of combining all kinds of map layers with imagery for a richer, more significant understanding.
Almost overnight, everyone with access to a computer became a GIS user.
A range of applications
By now, it’s apparent that imagery enables whole new perspectives and insights into your world and the issues you want to address. Imagery also has numerous advantages and capabilities.
Almost daily access to new information
Image collection is rapid and increasing. And access to imagery is increasingly becoming more responsive. Many satellites and sensors are already deployed with more coming all the time, collecting new data, adding to a continuous collection effort—a time series of observations about our planet. These image collections are enabling us to map, measure, and monitor virtually everything on or near the earth’s surface. All of us can quite rapidly gather much of the data that we need for our work. Imagery has become our primary method for exploration when we “travel” to other planets and beyond. We send probes into space and receive returns primarily in the form of imagery that provides a continuous time series of information observations. And it enables us to derive new information in many interesting ways.
Looking back in time
The use of aerial imagery is still relatively young. While imagery only began to be used in the twentieth century, it is easy to compare observations for existing points in time that reside in our imagery collections. In addition, we can overlay imagery with historical maps, enabling us to compare the past with the present.
Imagery data collections are becoming richer every day
Imagery is creating an explosion of discovery. Many imagery initiatives are repetitive and growing, expanding and adding to image databases for our areas of interest. ArcGIS is scaling out, enabling the management of increasingly large, dynamically growing earth observations. This points to the immediacy of imagery and its capacity for easy integration, enabling all kinds of new applications and opportunities for use—things like before-and-after views for disaster response, rapid exploitation of newly collected imagery, image interpretation and classification, and the ability to derive intelligence. Over time, many of these techniques will grow in interesting new ways, enabling deeper learning about our communities, the problems and issues we face, and how we can use GIS to address these.
Imagery enables powerful analytic capabilities
Imagery and its general raster format enable rich analysis using ArcGIS. And, in turn, these enable more meaningful insights and perspectives about the problems we want to address.
This post is excerpted from The ArcGIS Imagery Book: New View, New Vision. Imagery is suddenly a big deal, and those who are adept at finding it, analyzing it, and understanding what it actually means are going to be in demand in the years ahead. The purpose of this book is to help everyone from GIS professionals to app developers, and web designers to virtually anyone how to become smarter, more skillful, and more powerful appliers of image data. The book is available through Amazon.com and other booksellers, and is also available at http://www.TheArcGISImageryBook.com for free.
Putting remotely sensed image data to work
Imagery provides more than just plain pictures. Some sensors detect energy beyond what is humanly visible, allowing us to “see” across broad swaths of the electromagnetic spectrum. This enables scientists, geologists, farmers, botanists, and other specialists to examine conditions, events, and activities that would otherwise be hidden. The implications are profound and the applications are seemingly endless.
Expanding your point of view
Every day, the earth is directly imaged from scores of sensors in the sky and from orbit in space. Almost everything that happens is measured, monitored, photographed, and explored by thousands of imaging devices mounted on satellites, aircraft, drones, and robots. Much of this information ends up as imagery that is integrated into a large living, virtual GIS of the world, deployed on the web.
Some of these sensors see beyond what our eyes see, enabling us to view what’s not apparent. Multispectral imagery measures and captures this information about a world that has many more dimensions than just the colors of the rainbow—it sees past the limits of what our eyes perceive.
The electromagnetic spectrum
In the early history of powered aircraft, aerial photographs—pictures of the earth from above—began to be found useful for military and scientific applications. Quite quickly, imaging professionals and scientists realized that it was possible to detect beyond what is visible to the unassisted human eye. Deeper and richer information could be revealed by detecting waveforms from beyond the rainbow of visible light, into the invisible. As it turns out, these hard-to-detect realms of the spectrum offered some of the most meaningful insights. Hidden in these signals were previously unknown facts about Earth that have enabled us to understand our world far more effectively than had been possible.
Story Maps let you combine interactive maps and scenes with rich multimedia content to weave stories that get noticed. Here are some things you should consider when creating story maps.
Think about your purpose and audience
Your first step is to think about what you want to communicate with your story map and what your purpose or goal is in telling the story. Who is your audience? Are you aiming your story at the public at large, or a more focused audience, like stakeholders, supporters, or specialists who would be willing to explore and learn about something in more depth?
Spark your imagination
Go to the Story Maps Gallery to see some examples handpicked by the Esri Story Maps team to inspire you and highlight creative approaches. You can filter and search the gallery to check out how authors have handled subjects and information that may well be similar to yours. Explore. Get a gut feel for what makes a good story.
Information gathered from a distance
Remote sensing—the acquisition of information from a distance—has had a profound impact on human affairs in modern history. This image of British Beach (the WWII code name for one landing spot of the June 1944 Normandy invasion) taken from a specially equipped US Army F5, reveals rifle troops on the beach coming in from various large and small landing craft. Seven decades later—even as its application has expanded to unimaginable reaches—remote sensing remains the most significant of reconnaissance and earth observation technologies.
Many platforms, many applications
Modern imagery is captured from a broad range of altitudes starting from ground level to over 22,000 miles above earth. The images that come from each altitude offer distinct advantages for each application. While not meant to be an exhaustive inventory, let’s take a look at some of the most commonly used sensor altitudes.
Your own GIS is simply your view into the larger system. It’s a two-way street. You consume information that you need from others, and in turn, you feed your information back into the larger ecosystem.
Geography is key for integrating work across communities
Modern GIS is about participation, sharing, and collaboration. As a Web GIS user, you require helpful, ready-to-use information that can be put to work quickly and easily. The GIS user community fulfills that need—that’s the big idea. GIS was actually about open data long before the term gained fashion because the people who were doing it were always looking for ways to deepen and broaden their own GIS data holdings. No one agency, team, or individual user could possibly hope to compile all the themes and geographic extents of data required, so people networked about this to get what they needed.
Humans have always sought the high vantage point above the landscape. Throughout history, whether from a treetop or a mountain peak or a rocky cliff, the view from above allowed our ancestors to answer important questions: Where is there water? Where is the best hunting ground? Where are my enemies? Aerial photography was first practiced by balloonist Gaspard-Félix Tournachon in 1858 over Paris. With the advent of both photography and practical air flight in the early twentieth century, the advantages of having the high ground led to a quantum shift forward and the field of remote sensing was born.
The technology came of age rapidly during World War I as a superior new military capability. From 1914 to 1918, aerial reconnaissance evolved from basically nothing to a rigorous, complex science. Many of the remote sensing procedures, methods, and terminology still in use today had their origins in this period. Throughout World War II the science and accuracy of remote sensing increased.
Getting the z-terminology straight
Maps and Scenes
GIS content can be displayed in 2D or 3D views, and there are a lot of similarities between the two modes. For example, both contain GIS layers, both have spatial references, and both support GIS operations such as selection, analysis, and editing.
However, there are also many differences. At the layer level, telephone poles might be shown in 2D as brown circles, while the same content in 3D could be shown as volumetric models—complete with cross members and even wires—that have been sized and rotated into place. At the scene level, there are properties that wouldn’t make sense in 2D, such as the need for a ground surface mesh, the existence of an illumination source, and atmospheric effects such as fog.
There may be hundreds of thousands, if not millions, of undiscovered ancient sites across the globe, and Sarah Parcak wants to locate them. As a satellite archaeologist, she analyzes infrared imagery collected from far above the earth’s surface and identify subtle changes that signal a man-made presence hidden from view. Doing so, she and her colleagues aim to make invisible history visible once again—and to offer a new understanding of the past.
A Change in Perspective
3D is how we see the world. With 3D Web GIS, you bring an extra dimension into the picture. See your data in its true perspective in remarkable photorealistic detail, or use 3D symbols to communicate quantitative data in imaginative ways, creating better understanding and bringing visual insight to tricky problems.
The Evolution of 3D Mapping
Throughout history, geographic information has been authored and presented in the form of two-dimensional maps on the best available flat surface of the era—scrawled in the dirt, on animal skins and cave walls, hand-drawn on parchment, then onto mechanically printed paper, and finally onto computer screens in all their current shapes and sizes. Regardless of the delivery system, the result has been a consistently flat representation of the world. These 2D maps were (and still are) quite useful for many purposes, such as finding your way in an unfamiliar city or determining legal boundaries, but they’re restricted by their top-down view of the world.