Tag Archives: academic
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.
Multispectral imagery: Enabling extrasensory perception
One of the most extraordinary types of imagery collected by remote sensing is multispectral imagery. Each image is composed of data from a series of onboard sensors that collect small slices (or bands) across the electromagnetic spectrum. The table below shows the complete list of wavelengths (expressed as bands) that are collected by the Landsat 8 imagery according to what they capture. The images below are examples of what you “see” by combining different bands into red, green, and blue electronic displays or hard-copy prints.
The Natural Color (bands 4, 3, 2) combination of red, green, and blue is well suited for broad-based analysis of both terrestrial and underwater features and for urban studies.
Color infrared photography, often called false color photography because it renders the scene in colors other than those normally seen by the human eye, is widely used for interpretation of natural resources.
Land and water interface
Landsat GLS Land and Water Boundary (bands 4, 5, 3) emphasizes the edges between land and water.
This 6, 5, 4 band combination shows irrigated vegetation as bright green. Soils appear as tan, brown, and mauve.
Multispectral band combinations
Multispectral imagery measures different ranges of frequencies across the electromagnetic spectrum. One way to think of these different frequencies is as colors, where some colors are not directly visible to human eyes. These frequency ranges are called bands. Different image sensors measure different band combinations. The longest-running and perhaps most well-known multispectral imaging program has been Landsat, which began Earth image collection in the 1970s. By assigning data from three bands of the sensor to the red, green, and blue channels of an electronic display (or printer for a hard copy), color visualizations are created. Here are some examples of various alternate band combinations and their applications.
Panchromatic imagery, commonly known as pan, is typically recorded at a higher resolution than the multispectral bands on any given satellite. It remains a critical source for many GIS applications as a reference for basic interpretation and analysis. Pan is often combined with other bands through a process called pansharpening to generate higher-resolution scenes.
In the Agricultural band (combination 5, 4, 1) vigorous vegetation appears bright green, healthy vegetation appears as a darker green, and stressed vegetation appears dull green.
The Normalized Difference Moisture Index (NDMI) estimates moisture levels in vegetation where wetlands and vegetation with high moisture appear as blue growing to dark blue for higher moisture levels, and drier areas appear as yellow to brown shades. Image analysts often apply a formula to combine the selected multispectral bands to calculate various indexes.
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.
Special keynote address, discussion panel, and reception to engage and enlighten scientists
- A keynote address by Margaret Leinen, Director of the Scripps Institution of Oceanography, current president of the American Geophysical Union, and a US State Department Science Envoy.
- A conversational reaction panel of GIScientists moderated by Mike Goodchild (UCSB Geography emeritus) with John Wilson (USC Spatial Sciences Institute), Marco Painho (U. Nova de Lisboa Geography), Ming Tsou (San Diego State Geography), and Cyrus Shahabi (USC Computer Science).
- Audience Q/A and discussion.
- Networking reception: Enjoy stunning views of the San Diego Harbor, delicious appetizers, and a hosted bar of beer, wine, soft drinks, and bottled water.
Updated December 10, 2015
Science at Esri continues to be an exciting initiative where we are concerned with supporting both basic and applied science, while also recognizing that there are many major themes of compelling interest to society that will drive scientific research for the next two decades. Thus we view science as helping us to understand not only how the Earth works, but also how the Earth should look (e.g., by way of geodesign), and how we should look at the Earth (i.e., by way of Earth observation in varying forms and the accompanying data science issues of analysis, modeling, developing and documenting useful datasets for science, interoperating between these datasets and between various approaches). In addition to supporting the science community, we seek to do good science at Esri ourselves, as it underpins much of what we do as an organization. This is helping us to evolve ArcGIS into a comprehensive geospatial platform for science; a platform that supports research project management and collaboration, spatial analysis, visualization, open data, and communication of science, all at multiple scales (i.e., from individual researcher to lab workgroup, to multi-department, multi-university, university-to-agency collaboration, to citizen engagement).
You can always track the totality of the Esri science initiative at esriurl.com/scicomm,Hot! but in this post I’ll share some highlights from 2014, and as we near the end of 2015′s first quarter, talk about the immediate road ahead. Continue reading
Next-generation techniques are already changing the way we do science. Recently the National Academy of Sciences convened a Workshop on Identifying Transformative Research in the Geographical Sciences. Given that so many of the challenges that we currently face are place-based … Continue reading
Updated April 17, 2016
With all the recent excitement and good hopes over the White House Climate Data Initiative, and the ongoing progress of the Global Earth Observation System of Systems (GEOSS), there is another huge data initiative that bears mention: EarthCube.
I have used the word “initiative” for EarthCube but it has also been described as a vision, as a multi-faceted, multi-layered partnership, and also as a “virtual organization.” As such, it bears quite a bit of resemblance to the international GEOSS, but is much more US-based, having been conceived and currently funded by the US National Science Foundation (NSF). Continue reading
In an earlier post, I had mentioned Esri’s involvement in the large National Science Foundation-funded project known as CyberGIS, which aims to establish a fundamentally new software framework via a seamless integration of cyberinfrastructure, GIS, and spatial analysis/modeling capabilities, particularly … Continue reading
Updated: August 12, 2016 Jump to: Current Projects | Other Initiatives | Staying Connected | Deepsea Dawn2016 UC Science Symposium NEW! | R – ArcGIS Integration Hot! | 2015/’16 Road Map Hot! At Esri we are concerned with supporting basic … Continue reading
“We, the people, still believe that our obligations as Americans are not just to ourselves, but to all posterity. We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations. Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms.”
Thus spoke President Barack Obama in his 2nd inaugural address, to the delight of many, if not most in the scientific community. Indeed, there are many societal problems across the world that increasingly revolve around science. These include pollution and waste management, pandemics and biosecurity, access to clean air and clean drinking water, response to and recovery from natural disasters, choices among energy resources (oil and gas versus nuclear versus “alternative”), and the loss of open space in urban areas, as well as biodiversity in rural areas. And yet, there is a tension between the world of science, which is focused on discovery, and the world of policy making, which is focused on decisions.
Researchers today need to deal with an avalanche of data—from environmental sensor networks (both on land and at sea), social media feeds, LiDAR, and outputs from global- and regional-scale atmospheric circulation and general climate models and simulations. Because of this, “big data” is emerging as a major research theme for the academic community.
I recently had the opportunity to attend GIScience 2012, which is convened every two years and brings together leading researchers from around the world to reflect on a wide spectrum of geographic information science research areas. Attendees are normally university academics and graduate students working in the areas of geography, computer science, information science, cognitive science, mathematics, philosophy, psychology, social science, environmental sciences, and spatial statistics.