Spatial accuracy of orthorectified IKONOS imagery and historical aerial photographs across five sites in China

High-resolution (<= 1m) satellite imagery and archival World War II era (WW2) aerial photographs are currently available to support high-resolution long-term change measurements at sites across China. A major limitation to these measurements is the spatial accuracy with which this imagery can be orthorectified and co-registered. We orthorectified IKONOS 1m resolution GEO-format imagery and WW2 aerial photographs across five 100km(2) rural sites in China with terrain ranging from flat to hilly to mountainous. Ground control points (GCPs) were collected uniformly across 100km2 IKONOS scenes using a differential Global Positioning Systems ( GPS) field campaign. WW2 aerial photos were co-registered to orthorectified IKONOS imagery using bundle block adjustment and rational function models. GCP precision, terrain relief and the number and distribution of GCPs significantly influenced image orthorectification accuracy. Root mean square errors (RMSEs) at GCPs for IKONOS imagery were < 2.0m (0.9-2.0 m) for all sites except the most heterogeneous site (Sichuan Province, 2.6 m), meeting 1: 12 000 to 1: 4800 US National Map Accuracy Standards and equalling IKONOS Precision and Pro format accuracy standards. RMSEs for WW2 aerial photos ranged from 0.2 to 3.5m at GCPs and from 4.4 to 6.2m at independent checkpoints (ICPs), meeting minimum requirements for high-resolution change detection.