Satellite Imagery Production Grows Up: Land Cover for Local Governments

By Adena Schutzberg

The idea that the killer app for satellite imagery is a mapping portal is so 2007. With many cities focusing on environmental challenges, 2008 could be the year for a rush on land cover data that are typically drawn from satellite images and support the creation of GIS layers of "what's on the ground." This sort of information is gaining new life as cities and towns dig into the environmental and climate challenges involving water and air quality and other green topics. That's what three companies are counting on as they introduce land cover datasets for the Chicago area next month.

RFP Mapping LLC, a GIS data and imagery reseller and consulting firm, and Baxter & Woodman, an engineering firm, both based in Crystal Lake, IL, will take the lead in marketing and supporting the new datasets. NCDC Imaging & Mapping of Colorado Springs, CO creates the land cover data from satellite imagery. The first products being unveiled are land cover polygon layers built from 2006 and 2007 QuickBird 60 centimeter imagery. The first phase data, expected to be completed in May, will cover 1,800 square miles focused on Chicago and the inner suburbs. The second phase, expected to be completed in late summer, will expand the coverage area another 1,800 square miles to cover suburbs west of the city.

Data and Business Model
Unlike aerial firms that solicit contracts to fly municipalities and deliver imagery and land cover data, RFP Mapping and NCDC did the work speculatively. Does that sound risky? It didn't to NCDC's vice president of business development, Ian Hanou. His company had many requests for just such data, and that's what sparked the idea. "By using accelerated feature extraction and off-the-shelf imagery, we could put out a valuable product at a reasonable price, and cover a very large area."

Accelerated feature extraction describes traditional feature extraction enhanced with contextual and spectral input. Hanou's firm uses a variety of advanced software tools to turn the imagery into land cover GIS datasets with six land cover classes: impervious surfaces, tree canopy, irrigated grass areas, non-irrigated low-lying vegetative areas, bare soil and water features. Each pixel of each image is assigned to one of those categories, and then smooth polygons are created from the groups.

Why start with Chicago? Bill Peel of RFP Mapping stated the geographic reason. "We are here in the Chicago area and already work with many municipalities." But there are other reasons:
  • Recent data for the first phase were already acquired and in DigitalGlobe's archive.
  • Three hundred municipalities, many with high growth, are potential customers.
  • Interest in environmental issues, for compliance and service to citizens, is exploding in the region.
Data Use
That last point ties into how RFP and NCDC expect the data to be used. "We have extensive growth in the western suburbs," explains Hanou. That growth stresses the water table, so municipalities need to think about recharge. Ground water recharge is determined by the percentage of land that can transfer rainwater into the soil. Growth also pushes demand for stormwater management, since growth tends to bring an increase in impervious surfaces like paved driveways, roads and parking lots, which send more water to the system. In addition, new and older developments must plan for and comply with the EPA's Clean Water Act, perform hydrologic modeling and degradation assessments, develop long-term water conservation strategies and address biodiversity. For now, these green topics are the most popular concerns the dataset can address, but Hanou sees many other possibilities, including use in public health and telecommunications.

Baxter & Woodman has an exclusive relationship with RFP Mapping to provide the datasets to its clients and support them in their use. The engineering firm already works with more than half of the municipalities in the area on wastewater design and management and other engineering areas. RFP Mapping is serving as the dataset's "evangelists." With much of the phase-one data complete, the evangelizing has begun: RFP Mapping will meet with some 30 planners this month in McHenry County to begin introducing the land cover dataset and how it can be used. While the details can't yet be shared, several customers are close to signing contracts. It seems the speculative data creation will pay off very soon.

This figure shows a composite of land covers. (Click for larger image) These links will display images of individual land covers: bare soil, impervious surface, tree canopy, water, healthy grass / irrigated area, unhealthy grass / non-irrigated area, grass / medium health.
What's in the future? Hanou sees the Chicago project as a blueprint of what can be done elsewhere. He notes a second city is already in mind, and points out that land cover data need to be updated relatively frequently in fast growing areas, perhaps as often as every two years. Slower growing areas, and projects specifically looking at tree canopy growth, require lower return frequency, perhaps every five years.

My Take
This venture looks like a winner. Several characteristics that point that way:
  • reliable data source - imagery options are growing as more satellites are launched
  • automation - a unique, highly automated production process keeps labor costs down and enhances repeatability
  • large area model - developing data for 2,000 square miles at a time keeps costs low and opens the door for sales to counties, regional planning agencies and other consortia
  • model can be duplicated - U.S. cities are a next logical step, but there's no reason that cities worldwide can't be future targets
I, for one, am excited to see innovative, value-added processing of satellite imagery. The little bursts seen in recent years seem to come and go quickly. Perhaps we've turned a corner and this will be the first of many data layers regularly extracted from the terabytes of high-resolution satellite imagery data available worldwide and turned into products for immediate use in the public and private sector.

Published Friday, April 25th, 2008

Written by Adena Schutzberg

If you liked this article subscribe to our bimonthly newsletter...stay informed on the latest geospatial technology

Sign up

© 2017 Directions Media. All Rights Reserved.