High‐accuracy photogrammetric technique for human spine measurement

Abstract

Close range photogrammetry has been recognised as an essential tool for the capture of high‐accuracy spatial data for medical applications, in particular work involving dynamic human body parts such as limbs. Offline and online photogrammetric systems are readily available for a number of common applications. However, off‐the‐shelf systems are not always appropriate because of project site conditions. To achieve high measurement accuracy in a field environment, a modified field camera calibration technique was introduced. The technique is particularly important where each camera is limited to one captured image during calibration, as the camera and the calibration testfield are in fixed positions. In this paper a custom‐built imaging system designed for the study of the human spine in an outdoor environment is introduced. The discussion addresses: (1) imaging system design; (2) modified field calibration techniques; and (3) a case study on human spines. Two field camera calibration techniques were evaluated, both of which improved the accuracy of the prototype system, the use of a detachable target board offering the best results. This modified camera calibration procedure has improved the 3D measurement accuracy from 1·25 ± 0·3 mm to 0·43 ± 0·1 mm. The improvement is at a level achievable in the laboratory. The technique is considered to provide accurate and reliable anthropometric landmark measurement at low cost. This was evaluated in a clinical setting where diurnal changes in spine length and contour were measured in a cohort of 30 university students. The capability of the technique to measure sagittal and frontal angular changes provides a novel way of examining changes in spine shape.

A 3D Spine and Full Skeleton Model for Opto-Electronic Stereo- Photogrammetric Multi-Sensor Biomechanical Analysis in Posture and Gait

“…Given the restrictions above, it has been demonstrated that, in this context, a technique, named opto-electronic stereo-photogrammetry, offers a significant solution for the capture of functional information necessary for addressing clinical problems in rehabilitation medicine and is increasingly being reported in the literature for use in exploring different original approaches [1,[6][7][8][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Basically, this approach is reliant on the possibility of obtaining 3D measurement of points in space using a number of calibrated TV cameras (at least two) using stereo-vision principles.…”

“…Among the various 3D opto-electronic stereo-photogrammetric original approaches presented in the literature [6][7][8][18][19][20][21][22][23][24][25][26][27][28][29][30], we focus here on a new recently proposed integrated stereo-photogrammetric opto-electronic system named GOALS 1 (Global Opto-electronic Approach for Locomotion and Spine based on Optitrack 2 hardware) fully founded on the protocol and procedural techniques formerly presented by D'Amico et al [7] together with the subsequent development and upgrading of the system [6-8, 17, 27-30].…”

A 3D scanner design based on line-laser stripping

“…Bir çok ters-mühendislik probleminde, bir nesneye ait 3B sanal modelinin elde edilmesi endüstriyel amaçlı uygulamalar için büyük önem taşır. 3B modeller fiziksel nesnelerde zaman içerisinde oluşabilen fiziksel deformasyonların belirlenmesinde, endüstriyel animasyon uygulamalarında, robotik navigasyonda, endüstriyel kalite/kontrol ve imalat süreçlerinde, biyomekanik analizlerde [2], kültürel varlıkların restorasyonunda/arşivlenmesinde ve desen tanıma uygulamlarında sıkça kullanılmaktadır. 3B modellerin elde edilmesi için geliştirilmiş bir çok endüstriyel tarayıcı bulunmaktadır [3,4].…”

Non‐Rigid Surface Matching and Its Application to Scoliosis Modelling

“…Measured back surface topographies have been used to monitor the external manifestation of scoliosis to avoid excessive exposure to large doses of radiation which may increase the risk of breast cancer (Levy et al, 1996; Morin Doody et al, 2000). The demand for back surface topographies has meant that scoliosis has for many years been an area of interest for photogrammetrists (Chong et al, 2009). Matching back surface topographies from two successive clinical visits to monitor the scoliotic changes has been seen by the writers as advantageous and has been investigated in the work reported here.…”