Photogrammetric Measurement Error Associated with Lens Distortion

Abstract

All camera lenses contain optical aberrations as a result of the design and manufacturing processes. Lens aberrations cause distortion of the resulting image captured on film or a sensor. This distortion is inherent in all lenses because of the shape required to project the image onto film or a sensor, the materials that make up the lens, and the configuration of lenses to achieve varying focal lengths and other photographic effects. The distortion associated with lenses can cause errors to be introduced when photogrammetric techniques are used to analyze photographs of accidents scenes to determine position, scale, length and other characteristics of evidence in a photograph. This paper evaluates how lens distortion can affect images, and how photogrammetrically measuring a distorted image can result in measurement errors. Lens distortion from a variety of cameras is analyzed, and the ultimate effect that this distortion has on the image is evaluated, with a discussion on the overall difference this distortion would cause to measuring evidence in an image, such as tire mark distances and curvature. Ways of correcting this distortion are also addressed.

Development, comparison, and evaluation of software for radial distortion elimination

“…Such software claims that it can automatically identify and remove the radial distortion from a digital image. In fact, these pieces of software only require that the user supplies the image [15][16][17] . The greatest advantage of this software is that it offers the ability of automatic elimination of radial distortion and correction of a digital image.…”

“…where ρ d is the normalized radial distortion on the distorted image and ρ u respectively on the undistorted image 16 . The four non-physical parameters of the model influence a different area of the image.…”

“…Clearly, a manual undistortion is available if any problem acquired. Furthermore, this software is ideal for the processing of a great amount of images, since it gives the user the opportunity to save and reuse the settings (camera, lens, focal length) for the process of other images [15][16][17] .…”

“…It is important to note that the majority of such software performs internal processes, blocking the user from knowing and interfering in the employed methods. In any case, this software defines the required parameters, for the elimination of the radial distortion and the production of a distortion-free image, according to the chosen radial distortion model and the offered database [15][16][17] . Notable characteristics of the examined software are separately elaborated in depth below:…”

A Method for Automatic Image Rectification and Stitching for Vehicle Yaw Marks Trajectory Estimation

“…Practically it is not possible to ensure the constant position of the camera with respect to the pavement. Therefore, the tire straight skid mark segmentation and slope angle detection based on line searching image-processing technique is applied to solve problems associated with manual measurement [16,17]. The first step in the analysis of the tire mark images requires feature point extraction algorithm in order to stitch the current image with the next one (a consequent image).…”