RapidEye PCM: An Innovative and Cost-effective Approach to Updating Cartographic Datasets
ISBN 978-85-88783-11-9
Authors
1Douglass, S.
1BLACKBRIDGE Email: scott.douglass@blackbridge.com
Abstract
One of the biggest challenges currently facing any provider of cartographic data is to ensure that these data are as up to date as possible, to meet the needs of a diverse base of end users. Updating and maintaining large, complex cartographic datasets can be time and resource intensive. In addition to an already complex production and update process, users demand higher accuracy and more frequent refresh or update periods. All of these demands come at a time of decreasing budgets and a reduction in the number of personnel available to do the work. These conflicting drivers are forcing many providers to re-evaluate their existing workflows and seek more cost-effective and innovative approaches to their data production. To alleviate some of these problems, BlackBridge has partnered with MDA Information Systems LLC (MDA) to create RapidEye Persistent Change Monitoring (PCM). RapidEye PCM speeds up the process of identifying areas with significant change allowing the user to update larger cartographic datasets faster, while at the same time, doing so with reduced effort. Persistent Change Monitoring (PCM) is MDA’s patented change detection method that uses a stack of multispectral satellite images from different dates to discriminate lasting changes from changes caused by seasonal differences or other effects. This differs from previous change detection approaches because RapidEye PCM uses many images over longer periods of time to screen out variability due to seasonal or illumination differences between images. Since changed features typically comprise less than 1% of most geospatial datasets, RapidEye PCM allows for the prompt identification of areas with significant or enduring changes. Unlike other more traditional change detection methods, RapidEye PCM identifies only areas of lasting changes, such as new construction or permanent infrastructure changes, which allows the user to save a substantial amount of time and effort normally required than if the same area were scanned manually at full resolution. RapidEye PCM takes advantage of the resolution, extensive archive, and wide area collection capacity of BlackBridge’s multispectral RapidEye satellites. This constellation of five identical earth observation satellites allows for frequent broad area coverage with a 77 km swath width. Combined with the five spectral bands and a 5-meter orthorectified pixel size, RapidEye images are an ideal source for monitoring change on a regional or countrywide basis. The MDA-patented PCM change detection process, when combined with RapidEye imagery, can locate small-scale features down to five by five meters. When used in conjunction with a higher-resolution image source for ground truth, RapidEye PCM can enable updates of geospatial datasets up to 1:5,000 scale. It can also easily detect changes to narrow roads and small urban features. RapidEye PCM is a simple raster file that can be integrated seamlessly into an existing workflow in combination with a pre-existing, but outdated cartographic vector layer and a higher-resolution image source to help quickly produce up-to-date vector cartographic layers. RapidEye PCM is typically used to: - Generate tip-offs to new or changed features and construction, - Maintain currency of existing cartographic databases, - Monitor activities in remote or inaccessible areas, - Prioritize updates and maintenance of cartographic datasets. In this presentation, the challenges surrounding the update process, as well as the benefits provided by RapidEye PCM will be discussed. In addition, real world examples of the types of features detected by RapidEye PCM, from a number of different cartographic update scenarios, will be presented.
Keywords
Remote sensing; Cartographic data; Change Detection