This is PART ONE of a multi-part, monthly series whose subject is the commercial side of satellite imagery, or, if you prefer, remote sensing...
by Hartley & Pattie Lesser
and a cast of dozens of subject-specific experts
The world our grandparents, fathers, and mothers experienced was far larger than the world we occupy today. Faster vehicles have sliced distance to the point where a trip overseas requires little in the way of second thought … (except as to exactly what we must pack). Communication with other countries is a snap—areas of the globe once the domain of intrepid explorers and the ink-smudged fingers of cartographers are now mapped quickly, and in high resolution — by satellites.
What is now so easily downloaded for viewing on your computer screen, your mobile device, and your GPS unit, first had to be captured, in most instances, by the instruments resident within a satellite.
Such imagery capture is far from instantaneous — a satellite captures raw data and requires various applications, as well as revisits, to ensure a complete picture of any area. Applications of various algorithms are required to then morph that data into a usable image. Other location data sets require the satellite image be spatially rectified and combined with raster or vector data.
The databases that process satellite images are enormous in size—to produce a usable image is time consuming. In addition to the amount of time required to create a viewable image, weather can also hinder a satellite’s quest for data. Frequent cloud cover over mountaintops is especially difficult, as spacecraft’s current generation of instruments have difficulty penetrating thick weather blankets.
Different satellites offer various image resolutions. For example, the WorldView-1 satellite is able to credibly distinguish between objects on the surface that are at least 50 centimeters apart. This is a 50-cm resolution, and there are some smaller areas of the globe offering 10-cm resolution. There are panchromatic images, multispectral images, and the list goes on and on…
Remote sensing means just that—remote. Data is acquired without being in contact with the target. The information is collected through the use of various sensors. As the sensors are not in direct contact with their targets, data can be obtained regarding inhospitable or dangerous areas, locations where other means of information acquisition simply could not occur. For example, such would include data acquisition for military operations over hostile areas, or data assembly of areas surrounding active volcanoes. Additionally, satellites do not disturb the areas where data is being acquired.
Remote sensing may be categorized as either passive or active. For the former, a target area may reflect or emit natural energy (radiation), which is observed and recorded. Active remote sensing encompasses technology such as radar, where energy is emitted onto the target area and the reflective radiation is captured by a passive sensor and measurements obtained. Earth observation satellites capture multiple wavelengths of electromagnetic radiation to record landmass, called thematic mapping. Other satellites use interferometric synthetic aperture radar for the creation of digital elevation models involving the mapping of large-scale terrain areas. Additional sensors used include photometers and radiometers. They capture visible and invisible infrared, microwave, gamma ray and, sometimes, ultraviolet frequencies. Some sensors can also capture the data required for conversion by software applications into stereo pairs for topographic map creation.
Once the data is collected, processing is required. The quality of the final product is dependent upon a variety of resolutions. Spatial resolution, spectral resolution, radiometric resolution, and temporal resolution are all considerations for the final product. This data must be extrapolated in relation to a reference point and includes distances between known points on the ground, which is highly dependent upon the sensor type being used. This is called georeferencing, where data is tied to a real-world coordinate system. The images may then need to be corrected, with scale given to pixel values and each frequency band being rescaled to eliminate the haze of the atmosphere.
SSO
SSO is the acronym for sun synchronous orbit. This orbit is designed to enable the satellite to always pass over a location at the same solar time. This term is used constantly when discussing remote sensing satellites. The SSO illustration on page 34 is courtesy of NASA’s Landsat-6 Programming and Control Handbook, with more information at the Landsat-6 Handbook website.
GIS Matters
Another constantly used acronym you will frequently encounter is GIS. This is the acronym for geographic information system. A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.
GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts. ESRI, a company that’s been in business since 1969, is the fourth largest, privately-held software company in the world, and they design and develop GIS technologies. They offer our readers the following information regarding GIS… all images are courtesy of ESRI.
Three Views of a GIS
A GIS is most often associated with a map. A map, however, is only one way you can work with geographic data in a GIS, and is only one type of product that can be generated by a GIS. A GIS can provide a great deal more problem-solving capabilities than using a simple mapping program or adding data to an online mapping tool (creating a “mash-up”).
The Database View
A GIS is a unique kind of database of the world—a geographic database (geodatabase). It is a “Geographic Information System.” Fundamentally, a GIS is based on a structured database that describes the world in geographic terms. The geodatabase is the common data storage and management framework and can be used wherever it is needed—on desktops, in servers (including the web), or in mobile devices. It supports all the different types of data that can be used by various GIS programs, such as ESRI’s ArcGIS software. The geodatabase offers you the ability to...
- Store a rich collection of data types in a centralized location.
- Apply sophisticated rules and relationships to the data.
- Define advanced geometric relational models (e.g., topologies, networks).
- Maintain integrity of spatial data.
- Work within a multi-user access and editing environment.
- Integrate spatial data with other IT databases.
- Easily scale your storage solution.
- Support custom features and behavior.
A GIS is a set of intelligent maps and other views that show features, and feature relationships, on the earth’s surface. Maps of the underlying geographic information can be constructed and used as “windows into the database” to support queries, analysis, and editing of the information.
The Model View
A GIS is a set of information transformation tools that derive new geographic datasets from existing datasets. These geoprocessing functions take information from existing datasets, apply analytic functions, and write results into new derived datasets.
By combining data and applying some analytic rules, you can create a model that helps answer the question you have posed. GPS and GIS were used to accurately model the expected location and distribution of debris for the Space Shuttle Columbia, which broke up upon re-entry over eastern Texas on February 1, 2003.
Together, these three views are critical parts of an intelligent GIS and are used at varying levels in all GIS applications. GIS manages, analyzes, and displays geographic knowledge, which is represented using a series of information sets. These information sets can include:
Maps and Globes
Interactive views of geographic data to provide answers to many questions, to present results, and to use as a dashboard for real work. Maps and globes provide advanced GIS applications for interacting with geographic data.
Geographic Datasets
File bases and databases of geographic information—features, networks, topologies, terrains, surveys, and attributes.
Processing and Workflow Models
Collections of geoprocessing procedures for automating, and repeating numerous tasks that perform analysis.
Data Models
GIS datasets are more than RDBMS tables. They incorporate advanced behavior and integrity like other information systems. Data models—the schema, behavior, and integrity rules of geographic datasets—play a critical role in GIS.
Metadata
Documents describing the specifications and properties of the data. A document catalog enables users to organize, discover, and gain access to shared geographic knowledge.
ESRI has a great deal of information available regarding GIS and how they apply their technologies in this highly technical field. To find out more about ESRI and their applications as well as remote sensing, we recommend you head over to their well-designed websites at www.gis.com and www.esri.com for additional information.
GIS + The World Of Homeland Security
The analysis of the GIS market continues, with estimation by Daratech in April of 2008 that estimated such worldwide revenues were 3.63B/USD in 2006. Their thoughts also encompass the ever-increasing interest of the Department of Homeland Security (DHS) and that agency’s realization of what remote sensing and geointelligence may be able to accomplish to help meet their objectives. Expect DHS’ interest and healthy budget to increase the remote sensing market as well as those who produce the tools for this business, which enable users to obtain the maximum use possible from the GIS data. In 2006, this vertical software accounted for 50 percent, data ranged at 25 percent, and GIS services at 20 percent of the market. Based in Cambridge, Massachusetts, Market Research Analyst may be accessed at their website.
Why the increased attention on DHS?
Homeland Security Market Research offers expertise for global clients to help them gain insight into the business opportunities that exist within the Homeland Security market. With nearly 300 private clients, including Fortune 500 companies, security decision makers, and government agencies, this research and analysis firm offers the following at their website...
The National Applications Office, which is a new DHS body, clears access of law enforcement, border security, Coast Guard and other agencies to critical satellite feeds. This move, while generating wide discussions over privacy issues and legal implications, may also have a profound impact on the market for commercial satellite imagery.
Currently access to satellite feeds is mostly in the domains of DoD (Department of Defense) and Intelligence Community. On the DoD side, Strategic Command coordinates all military and civilian space assets, while Air Force Space Command acquires and operates the majority of military satellites. The National Reconnaissance Office (NRO) operates the nation’s intelligence satellites, often known as National Technical Means (NTM).
Entrance of DHS into the sea of satellite information opens a window of opportunity for the vendors of commercial satellite imagery.
A report by Homeland Security Research Corporation 2007-2011 U.S. Homeland Security (Government & Private) Market Outlook forecasts that the U.S. Homeland Security markets, driven by the government and private sectors, will grow from about 24B/USD in 2006 to 35B/USD by 2011. Acquisition of intelligence data from the private sector will not be a small market, either.
The two main advantages regarding commercial imagery are the lack of legal restrictions on their use over the United States and the data’s unclassified nature. Privately owned commercial systems do not face the same restrictions as national systems. Their unclassified products can easily be distributed to anyone, provided the proper licenses are bought. This is important because many homeland-security agencies, especially at state and local levels, do not have the necessary security clearances for national imagery. In addition, the dissemination of these products can be done through the Internet, thus providing quick and easy access. The commercial satellite technology can map the border, ports and airports; potentially detect a tunnel under the border by seeing earth disturbances or unusual vegetation patterns and help the Coast Guard to zero in on a ship’s location. Because of these advantages, commercial imagery, as it becomes more available, can become a major source of data from space for homeland security.
A commercial satellite owned by Space Imaging (acquired by GeoEye) took some of the most widely recognized pictures of the 9/11 attacks. The New York governor’s office contacted Space Imaging directly to request information on the use of satellite imagery for disaster assessment and emergency management. It set a precedent whereby a state went directly to a private company rather than a federal agency for help on using space assets.
A Growth Environment
Satellites working within the imagery genre have experienced enormous growth. According to Business Communications Company (BCC) Research, and as reported by Space Foundation in their informative report The Authoritative Guide to Global Space Activity, sensing products revenue reached 7B/USD+ during 2006. The highest share of this total market is for weather forecasting, with 38 percent of the revenue. The growth of the total remote sensing market is nearly 50 percent, according to the American Society of Photogrammetry and Remote Sensing (ASPRS). BCC additionally reports that, by 2012, remote sensing data products will reach more than 9.9B/USD, with a growth rate of 6.3 percent, per year. This amount includes aerial, satellite platforms, and excludes products that are internal to governments.
An example of the importance of satellite imagery is the acquisition by Google of Keyhole Corporation and that company’s satellite imagery software, previously known as Earthviewer. If it hadn’t been economically feasible, and possessing outstanding growth potential, Google would have shown little interest… currently that software and its data linkages are part of the widely-used Google Maps and Google Earth products.
What Do Remote Sensing Sats Do?
There are a number of uses for satellite imagery produced for commercial consumption. They include, but are not limited to,
- Antenna tower site acquisition and coverage analysis
- Ecological and environmental monitoring (ozone, land use, pollution)
- Exploration and management of resources (agriculture, animals, forestry, minerals, oil, gas, vegetation)
- Emergency situation mapping
- Game development (visual simulation)
- GPS-controlled and tracked vehicles
- Location optimization
- Media use (TV, movies, newspapers, and so on)
- Orbital debris remediation
- Pipeline health and management
- Verification of treaties
- Weather conditions, forecasting and tracking
- Well monitoring
The distinctions between a remote sensing satellite and one dedicated to science work is not always clear—many satellites within the latter genre use remote sensing technologies. Such an example would be CARTOSAT, which is used by India for a variety of mapping applications.
The reason imagery satellites’ orbits are circular is that if images of different locations are to be used for comparison purposes; the target captures must be acquired from the same altitude. This means each satellite must have a constant altitude, relative to the Earth’s surface.
Remote sensing is a true collaborator for the condition of humankind, as well. Just one example finds GeoEye’s IKONOS Earth imaging satellite responsible for helping locate health-related natural resources.
Paclitaxal is a chemical substance that, once processed, can treat cancer. This chemical is found in the Canadian yew tree. IKONOS can locate this slow-growing shrub, which otherwise would be a most difficult task as they are located in small, remote pockets and they grow under neighborhood trees. The high-resolution, map-accurate results localize not only tree density, but also its health. Once IKONOS collects all of the raw data, the information is sent to ViaSat GeoTechnologies, who are located in Montreal, Quebec. They complete the data processing and analyze the data to isolate the yew tree to make their detection a far easier task.
Some of the terms used in this article may be unfamiliar—one of the most complete glossary sites we’ve found is the Remote Sensing Tutorial Page. This glossary was extracted directly from a site prepared by Dr. Jeff Weissel and others at the Lamont-Doherty Earth Observatory of Columbia University. You might wish to use this glossary in a second web browser page as a reference tool.
To Be Continued...
In the next issue of SatMagazine, we delve into the companies who own, operate, and license the imagery from commercial remote sensing satellites. We hope you’ll continue to share these verbal images of a highly dynamic and viable market segment of our industry—Hartley & Pattie Lesser