THE IGN CAMV2 SYSTEM Jean-Philippe Souchon (jean-philippe.souchon@ign.fr) Christian Thom (christian.thom@ign.fr) Christophe Meynard (christophe.meynard@ign.fr) Olivier Martin (olivier.martin@ign.fr) Marc Pierrot-Deseilligny (marc.pierrot-deseilligny@ign.fr) Institut Ge ´ographique National, Saint-Mande ´, France Abstract After 10 years of pioneering aerial digital camera development, IGN’s CAMv2 project began in 2006 with the main goal of upgrading the then current system. This had been used for research applications since 1996 in more than six different con- figurations and in production since 2003 configured with four coloured channels. The new system is still highly modular, enabling combinations of several ‘‘basic com- ponents’’, each consisting of one digital camera head with its storage and control unit. The new camera head was developed around the Kodak KAF-39 000, 39-mega- pixel array sensor (7216 · 5412 pixels). The system is also very versatile thanks to the possible choice of more than 10 different lenses (from 35 mm up to 180 mm focal length) and interchangeable spectral filters. The mechanical and electronic designs have been reduced in size so as to permit many different configurations including multiple camera heads on the same gyro-stabilised mount. The combination of the performance of camera heads and control and storage units allows a frame rate of one image per 2 s with storage redundancy and 1 s without, leading to a minimum ground sample distance (GSD) of about 9 cm with 60% overlap at an airspeed of 100 m/s. In order to use the new system to best advantage, the adjustment and cali- bration processes had to be improved. During the summer of 2009, three systems con- figured for colour imagery, each using four nadir-viewing camera heads (RGB and NIR), were used to acquire images for IGN production work. In January 2009, an eight-camera-head configuration was tested in order to achieve 155-megapixel pan-sharpened images with a pan-sharpening ratio of 2 · 2, and a final swath width of about 14 400 pixels. At that time this configuration needed two windows in the aircraft, but it is now installed on a single, bigger mount. Keywords: digital aerial camera, geometric calibration, mechanical design, modular system, national mapping, radiometric calibration Introduction The French National Mapping Agency, the Institut Ge ´ographique National (IGN), was developing aerial digital frame camera systems from 1996 up to 2006, in its LOEMI research laboratory. During these 10 years, the size of the CCD sensors increased from 6 megapixels up to 16 megapixels, and the number of camera heads per system varied from a single one up to The Photogrammetric Record 25(132): 402–421 (December 2010) Ó 2010 IGN. The Photogrammetric Record Ó 2010 The Remote Sensing and Photogrammetry Society and Blackwell Publishing Ltd. Blackwell Publishing Ltd. 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street Malden, MA 02148, USA.