Mapping / Remote Sensing Services

Helicopter Surveying
In the 1990s, helicopter-based aerial photography became a popular alternative to ground surveying. Today, transportation departments across the country routinely use helicopters to map and survey road and highway corridors. Here's why:

Accuracy
Helicopters can fly lower and more slowly than fixed wing aircraft, resulting in more accurate photogrammetric measurements. Whereas FAA regulations require fixed wing aircraft to fly at least 1,000 feet above the highest obstacle, helicopters can fly as low as 300 feet. The helicopter's lower altitude provides greater photographic detail and more accurate measurements of height, area, distance, and volume. Aerial photography captured by helicopter can provide three-dimensional ground coordinates (x, y, z) of roadway and ground features, including pavement edges, road crowns, travel lanes, medians, ramps, bridges, and tops and bottoms of curbs and gutters. Vertical accuracy for helicopter surveying can achieve +/- 0.05 feet, an accuracy level that is critical for road resurfacing and widening projects. Since areas to be surveyed are often within rights-of-way, foliage and vegetation pose no problem, and helicopter photography can be captured successfully year-round.

Safety
Using helicopters, densely populated, high-traffic corridors can be surveyed accurately and safely. Helicopter surveying reduces traffic disruptions and eliminates risks to field surveyors and citizens. As an added benefit, helicopter surveying can replace on-the-ground surveying of cross-sections in high-speed, heavily congested traffic areas, or the mapping of sites contaminated with toxic chemicals.

When it comes to surveying for road and highway mapping projects, helicopter surveying is clearly the best solution.

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Imagery Classification
Sanborn has developed sophisticated image classification techniques to fully exploit the value inherent in new data sources that offer improved spatial and spectral content. For example, Sanborn’s UltraCam large-format digital camera collects data in red, green, blue and near-infrared channels, 12 bits-per-channel, at more than one frame-per-second. This data is cost effective and offers practical technical options for urban and natural resource professionals alike. Sanborn is an industry leader in the use of this data for addressing land management problems in all disciplines.

Your land management needs will determine the level of detail and accuracy of the proper classification scheme for your project. Four levels of the standard land cover product are available—Impervious and Levels 1–3—but custom classifications are also available. Sanborn will work with you to determine the classification system that is best for your application.

If your needs are not met by the standard products there are a number of options such as:

• Custom classification schemes
  
• Quantitative accuracy assessment
  
• Subscription services for regular imagery updates
• Serving imagery and classification through web site

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Change Detection
The landscape changes continually as a result of human and natural forces. Change detection can be accomplished using satellite imagery or aerial photography, advanced image processing techniques, and GIS analysis to map the spatial location and magnitude of land cover change.

Sanborn has pioneered the development of remotely sensed change detection methods to provide the necessary information for good decision-making. We have conducted hundreds of projects that utilize image classification and multispectral satellite imagery to analyze land cover and its changes over time. The members of our team have successfully completed change detection projects covering millions of acres throughout the world, and continue to apply these methods to address our client’s forestry, fire and ecosystem management, urban planning, and emergency response requirements.

Change detection techniques applied in the natural resource management arena are used to identify changes in vegetation cover over time through natural or man-made events. The main deliverables include:

Accuracy Assessment
Accuracy is crucial to any mapping project developed from satellite imagery, particularly when the maps are used to make land and natural resource management decisions. Sanborn is a leader in assessing the accuracy of remotely sensed data and image classification. Our accuracy assessment methods are based on knowledge and experience gained from many years of working with top experts in the field. Our Senior Technical Advisor Dr. Russell Congalton is a pioneer in this field and co-authored the definitive book on the quantitative methods of accuracy assessment (Congalton and Green 1999).

The accuracy of remotely sensed maps is traditionally assessed by comparing a sample of the map data with actual ground conditions, typically by generating an error matrix. This approach is useful for both visualizing image classification results and, more importantly, for statistically measuring the results.

Sanborn’s accuracy assessment techniques have been implemented in dozens of projects, as both qualitative and quantitative assessments on land cover and fuels mapping products. Recent customers include federal and state agencies and forestry industry organizations. In various projects we have classified as many as 100 vegetation species, 45 land covers, 16 fuels, 16 agricultural types, 14 tree size/structures, 10 tree crown covers, and 9 non-vegetation classes. Accuracy assessments are conducted to ensure the final mapping products meet the customer’s requirements.

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