Bildemåling

Bildemåling, or image measurement, is the process of deriving quantitative information from images for dimensions, geometry, and physical properties. It sits at the intersection of photogrammetry, image analysis, and metrology, and aims to convert image data into accurate metric measurements. The practice relies on understanding the imaging geometry and the scene, often requiring calibration and controlled acquisition.

A typical workflow includes camera calibration to estimate intrinsic parameters (such as focal length, principal point, and lens distortion) and extrinsic parameters (the camera’s position and orientation relative to the scene). This is followed by image rectification, feature detection and correspondence, and the application of a measurement model to convert image measurements into real-world quantities. In stereo or multi-view configurations, triangulation computes three-dimensional coordinates from image correspondences. Active methods, such as structured light or laser-based systems, provide depth information that complements or replaces purely passive image-based measurements.

Accuracy in bildemåling depends on sensor resolution, calibration quality, imaging geometry, occlusions, noise, and lighting conditions. Uncertainties are assessed and reported as part of the measurement process. The method is used in industrial metrology and quality control, reverse engineering, architectural and cultural heritage documentation, surveying, robotics, and autonomous navigation.

Limitations include perspective distortion, lens effects, occlusions, and ambiguous features. A reliable scale must be established, typically via a known reference object or calibration target. Bildemåling is closely related to photogrammetry, computer vision, and optical metrology, and relies on standards and best practices to ensure reproducible results.