Imagery and GIS

Best Practices for Extracting Information from Imagery

Introduction 

Why Imagery and GIS? Imagery—it allures and fascinates us; its measurements inform us. It draws us in to explore, analyze, and understand our world.

Imagery and GIS

 First comes the astonishment of its raw beauty—the enormity of a hurricane, the stark glaciers in Greenland, the delicate branching of a redwood’s lidar profile, a jagged edge of a fault line in radar, the vivid greens of the tropics, the determined lines of human impact, the rebirth of Mount Saint Helens’ forests, the jiggly wiggly croplands of Asia and Africa, the lost snows of Kilimanjaro. Each image entices us to discover more, to look again and again. Then we start to ask questions. Why do trees no longer grow here? Can trees grow here again? How much has this city expanded?
Will the transportation corridors support emergency relief? Why did this house burn while the one next door is untouched by flames? What crops flourish here? Will they produce enough food to feed the people of this region? Why has this landscape changed so dramatically? Who changed it? When we bring imagery and GIS together we can answer these questions and many more. By combining imagery and GIS, we can inventory our resources, monitor change over time, and predict the possible impacts of natural and human activities on our communities and the world. This book teaches readers about the many ways that imagery brings value to GIS projects and how GIS can be used to derive value from imagery. Imagery forms the foundation of most GIS data. Whether it be a map of transportation networks, elevation contours, building footprints, facility locations, vegetation type, or land use, the information in most GIS datasets is derived primarily from imagery. Alternatively, GIS allows us to more efficiently and effectively derive information from imagery. Organizing imagery in a GIS brings the power of spatial information management and analysis to imagery. The purpose of this book is to unlock the mysteries of imagery, to make it readily usable by providing you with the knowledge required to make informed decisions about imagery. More than just an overview of remote sensing technology, this book takes a hands-on, decision-focused approach. Each chapter evaluates practical considerations and links to online interactive examples. The book also includes multiple real-world case studies that highlight the most effective use of imagery and provide advice on deciding between alternative image sources and approaches. The book provides guidance on 

1. choosing the best imagery to meet your needs; 

2. effectively working with and processing imagery; 

3. efficiently extracting information from imagery; and 

4. assessing, publishing, and serving imagery datasets and products

Why Now? 

Humans have always coveted a bird’s-eye view. The resulting knowledge of where we are relative to others and the resources we need has long been treasured and is necessary for survival. Remote sensing, the science of measuring the attributes of an object from a distance, provides us with imagery. Offering valuable insights into how humans interact with the earth, imagery and GIS allow citizens, governments, corporations, and nonprofits to fundamentally understand patterns of resource status, use, and change. It took thousands of years for humans to invent cameras and aircraft, but within 30 years of their invention they were combined, and remote sensing was born. In the late 1800s and early 1900s, early remote sensing systems consisted of cameras placed first on balloons and kites, and then on airplanes. Later, the military operations of World Wars I and II as well as the Cold War spurred remote sensing into a field of science, resulting in methods and technologies that allow us to analyze and measure features from a distance. Remote sensors are now everywhere—from your cell phone camera, to the video camera above your bank teller machine, to satellites hundreds of miles in space. Imagery and GIS support a broad array of applications including weather prediction, disaster response, military reconnaissance, flood planning, forest management, habitat conservation, wetland preservation, mineral exploration, famine early warning, agriculture yield estimates, urban planning, wildfire prevention and control, fisheries management, transportation planning, humanitarian aid, climate monitoring, and change detection.

Precision agriculture 

Information gathered during harvest, including yield at any given location, helps growers track their results and provides valuable input for calculating seeding and soil amendment rates for the following year

Humanitarian aid 

Access to up-to-date imagery shows tha creation of the Zaatari refugee camp over a nine-day period in July 2012. Designed to hold over 60,000 people, its population skyrocketed to over 150,000 before new camps relieved some of the pressure.

Forestry 

Dynamic access to data on forests in Europe is derived from the Corine Land Cover 2006 inventory. Corine means “coordination of information on the environment”. 

Mining 

The geologic nature of the landscape comes to life using earth-orbiting satellites. 

Natural disaster assessment 

This scene shows the destruction of Hurricane Sandy’s storm surge in Seaside, New Jersey. The active swipe map compares pre- and post event imagery from the National Oceanic and Atmospheric Administration (NOAA).

Engineering and construction 

Development projects actively under construction in the City of Pflugerville, Texas, are displayed here. 

Remote sensing has always been a rapidly changing field with technologies readily adopted as they become operational and cost effective. However, recently the pace of adoption has quickened. Long a staple of military operations, remotely sensed imagery has recently exploded for civilian use as availability and access have increased while prices have declined. This rapidly quickening pace of change results from the evolution of sensors from capturing images on film to capturing them on digital arrays. As a result, storing, accessing, and analyzing imagery have become much easier and faster. As microelectronic performance continues to improve, sensors will continue to become lighter, smaller, more powerful, and less expensive. platform improvements resulting in more agile and smaller platforms that are less expensive to operate. Besides airplanes and large satellites, imagery is now collected from unmanned airborne systems (sometimes called drones) and constellations of small satellites.
increasing accessibility because of growing supply, policy changes, and the ability to quickly serve cached imagery across the web. While much high-resolution satellite imagery is license restricted, both the United States and the European Union offer global imagery at no cost in the public domain from their moderate-resolution systems (Landsat and Sentinel), and high-resolution airborne imagery is freely available from many local, state, or federal agencies across the United States. Additionally, archived high-resolution imagery is readily available for free viewing on many web services, including ArcGIS Online, Google Earth, and Bing. improved positional accuracy. 

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