Abstract
Large format digital camera (LFDC) systems are becoming more broadly available and regularly collect image data over large areas. Spectral and radiometric attributes of imagery from LFDC systems make this type of image data appropriate for semi-automated change detection. However, achieving accurate spatial co-registration between multitemporal image sets is necessary for semi-automated change detection. This study investigates the accuracy of co-registration between multitemporal image sets acquired using the Leica Geosystems ADS40, Intergraph Z/I Imaging® DMC, and Vexcel UltraCam-D sensors in areas of gentle, moderate, and extreme terrain relief. Custom image sets were collected and orthorectified by imagery vendors, with guidance from the authors. Results indicate that imagery acquired by vendors operating LFDC systems may be coregistered with pixel or sub-pixel level accuracy, even for environments with high terrain relief. Specific image acquisition and processing procedures facilitating this level of coregistration are discussed.
Highlights
Commercial large format digital camera (LFDC) systems have been utilized for airborne collection of multispectral imagery since 2001
Imagery vendors were provided with specific image processing parameters in order to 1) ensure that the image co-registration techniques were comparable between the LFDC systems and 2) evaluate the co-registration that may be achieved using lower cost orthorectified products based on United States Geological Survey (USGS) digital elevation models (DEMs) and not incorporating surveyed ground control collection, custom digital terrain model (DTM) creation using stereo image products, nor purchase of high resolution terrain data (e.g., light detection and ranging (LIDAR) or interferometric synthetic aperture radar (IFSAR) products)
Excluding the UltraCam-D product provided by the vendor (UCD), the co-registration root mean square error (RMSE) between like image products was less than 2.1 pixels (0.32 m) regardless of terrain type
Summary
Commercial large format digital camera (LFDC) systems have been utilized for airborne collection of multispectral imagery since 2001. Studies utilizing Landsat satellite imagery for change detection have considered a spatial coregistration error of 0.5 to 1.0 pixels to be adequate for reducing misregistration artifacts in change detection products [3,4,5,6] Achieving this level of spatial co-registration with airborne imagery is complicated by the wide view angles utilized by airborne systems and the resulting image parallax [7]. Coulter et al (2003) [7] presented a technique for acquiring and precisely registering airborne frame imagery This technique, referred to as frame center (FC) matching [9], is based upon repeating the camera station positions in terms of horizontal position and altitude between multitemporal acquisitions. Four specific tools are required for operational FC matching using GPS data [7]: 1) GPS for logging and digitally archiving flight line and FC coordinates for each image acquisition; 2) Flight planning software integrated with digital coordinates of flight line and frame coordinates from previous image dates; 3) In-flight, heads-up display enabling a pilot to maintain flight line course and altitude (based on GPS coordinates); and
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