Close-range photogrammetry applied to the documentation of cultural heritage using telescopic and wide-angle lenses

Abstract

Close-range photogrammetry is widely used for numerically and graphically representing historical buildings for documentation. Such data can be later used as the base for conservation and restoration processes. The highest precision in point determination in photogrammetry can be achieved using a metric camera, although it is expensive. Recently, many studies have used SLR non-metric cameras, which have the advantage of a self-calibration method and furthermore, are cheaper than the metric camera. In most cases, for close-range photogrammetry applications that use an SLR digital camera, the object is close to the camera (less than 50 m), requiring a wide-angle setting. In our study, the precision achieved is based on a compact camera (Lumix TZ-10) used in building restitution. We experimented with the two extremes in close-range photogrammetry: close object, less than 15 m between the camera lens and to building faç ade; and distant object, up to 200 m between camera lens and building. In both cases, the precision achieved was suitable for the restitution of the historical buildings: under 1 cm for near objects using a 25-mm wide-angle lens and 3 cm for the distant object using a 280-mm telescopic lens. We achieved remarkable precision in the case of the tele lens, where it is unusual to use the focal length for building restitution in close-range photogrammetry. Nevertheless, a tele lens becomes necessary when it is not possible to place the camera near the object, as in the case of the northern faç ade of the Alhambra in Granada, Spain.

Three-dimensional recovering based on variable focal length via Bezier networks

“…Therefore, these systems take a long time to achieve measurements of variable range. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Moreover, the recalibration increases 0?3% initial measurement error. 16 Additionally, the re-calibration of camera position and focal length is not achieved when the references do not exist during vision task.…”

“…This procedure improves the measurements of variable range, which adjust the vision parameters via external re-calibration. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] The measurements of variable range via variable focal length are described in the section on 'Measurements of variable range via variable focal length'.…”

“…3c, where the camera position is moved to Z c and the line position is shifted from x 00 to ax 00 . The camera position Z c is computed via equation (8), where the parameters L, x c ,g and f 0 are known and ax 00 is calculated by image processing. Then, Z c is stored in the memory and the focal length is moved to f 1 .…”

“…Instead, the static set-up restricts the contouring of complex shapes, which contain big and small surface variations. [8][9][10] Moreover, the rigid configuration produces occlusions and low resolution. 11,12 Recently, lighting methods such as fringe pattern, line and spot have been implemented by means of a flexible set-up to provide measurements of variable range.…”

Fusing Georeferenced and Stereoscopic Image Data for 3D Building Façade Reconstruction

“…A number of façade reconstruction methods are based on close-range images or terrestrial laser data [1]. Close-range photogrammetry has been used to produce heritage building façade maps [2] for the documentation of historical buildings [3] and for architectural documentation [4]. The terrestrial laser point cloud has been extensively used to collect large datasets.…”