Comparative analysis of results obtained by calibration with three-dimensional and two-dimensional field methods

Automation resources have been used in Digital Photogrammetry in various applications. A complex and critical process in Photogrammetry, the camera calibration, can be performed automatically. Among the methods for camera calibration, field calibration using a set of two-dimensional or three-dimensional points can be mentioned. Some commercial software uses a 2D plotted sheet, which allows the automatic recognition of targets, such as Photomodeler. However, the three-dimensional calibration field can be more suitable for certain applications, for example, three-dimensional object modeling. Thus, it is relevant to assess the effects of the interior orientation parameters, resulting from the use of these techniques, in particularly to correlation between parameters. For this purpose, three calibrations trials were performed using three different test fields (two 2D fields and one 3D field), processed in commercial and scientific software's (Photomodeler and Calibração com Múltiplas Câmaras).The results were analyzed by comparing calibrations, assessing the influence of the interior orientation parameters in the reconstruction of targets coordinate in an image triplet. Two different situations (direct and indirect exterior orientation) were simulated and it was verified the impact of the interior orientation parameters in the in-plane and out-of-plane coordinates. The calibration with 3D field, compared to 2D field, reduced the correlation between the focal length and the Z coordinate of the perspective center, showing better results for the correlation between parameters in both orientations (direct and indirect). It was also observed better results when using 3D calibration field for the calculation of out-of-plan targets coordinates.

Camera Calibration; Field Calibration Method; Parameters Correlation; Photomodeler.