Exif Dependent Camera Calibration in Close Range Digital Photogrammetry

Abstract

The authors have been concentrating on developing convenient 3D measurement system using consumer grade digital cameras, and it was concluded that the system is expected to become a useful 3D measurement system for the various close range application fields. There were some issues, however, to realize a convenient photogrammetry using consumer grade digital cameras. One of issues is acquisition of accurate scale factor since pixel coordinates should be transformed into image coordinates using scale factor. Scale factor was generally computed using pixel numbers in a line on the display and sensor size which was given from manufacturer's specifications. Nevertheless, it became impossible to obtain sensor size for consumer grade digital cameras even from manufacturer's specification, and scale factor is unavoidably estimated from the sensor type such as 1/2 inch CCD sensor. On the contrary, focal length of digital cameras can be obtained from Exif file which is recorded on the image.
In these circumstances, Exif dependent (E-D) calibration was proposed in this paper. The most remarkable point of the E-D calibration is its ability to calculate both of exterior and interior orientation parameters without scale factor or manufacturer's specifications.