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Espinosa-Moyano I, Reina-Bueno M, Palomo-Toucedo IC, González-López JR, Castillo-López JM, Domínguez-Maldonado G. Study of the Distortion of the Indirect Angular Measurements of the Calcaneus Due to Perspective: In Vitro Testing. SENSORS (BASEL, SWITZERLAND) 2021; 21:2585. [PMID: 33917016 PMCID: PMC8067713 DOI: 10.3390/s21082585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/04/2021] [Accepted: 04/06/2021] [Indexed: 11/19/2022]
Abstract
The study of the foot is relevant in kinematic analyses of gait. Images captured through a lens can be subjected to various aberrations or distortions that affect the measurements. An in vitro study was performed with a rearfoot simulator to compare the apparent degrees (photographed) with the real ones (placed in the simulator) in the plane of the rearfoot's orientation, according to variations in the capture angle in other planes of space (the sagittal plane and transverse plane-the latter determined by the foot progression angle). The following regression formula was calculated to correct the distortion of the image: real frontal plane = 0.045 + (1.014 × apparent frontal plane) - (0.018 × sagittal plane × foot progression angle). Considering the results of this study, and already knowing its angle in the transverse and sagittal planes, it is possible to determine the angle of a simulated calcaneus with respect to the ground in the frontal plane, in spite of distortions caused by perspective and the lack of perpendicularity, by applying the above regression formula. The results show that the angular measurements of a body segment made on frames can produce erroneous data due to the variation in the perspective from which the image is taken. This distortion must be considered when determining the real values of the measurements.
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Affiliation(s)
- Isidoro Espinosa-Moyano
- Department of Podiatry, Faculty of Nursing, Physiotherapy and Podiatry, Universidad de Sevilla, C/Avice-na s/n, 41009 Seville, Spain; (I.E.-M.); (I.C.P.-T.); (J.M.C.-L.); (G.D.-M.)
| | - María Reina-Bueno
- Department of Podiatry, Faculty of Nursing, Physiotherapy and Podiatry, Universidad de Sevilla, C/Avice-na s/n, 41009 Seville, Spain; (I.E.-M.); (I.C.P.-T.); (J.M.C.-L.); (G.D.-M.)
| | - Inmaculada C. Palomo-Toucedo
- Department of Podiatry, Faculty of Nursing, Physiotherapy and Podiatry, Universidad de Sevilla, C/Avice-na s/n, 41009 Seville, Spain; (I.E.-M.); (I.C.P.-T.); (J.M.C.-L.); (G.D.-M.)
| | - José Rafael González-López
- Department of Nursing, Faculty of Nursing, Physiotherapy and Podiatry, Universidad de Sevilla, C/Avenzoar nº6, 41009 Seville, Spain;
| | - José Manuel Castillo-López
- Department of Podiatry, Faculty of Nursing, Physiotherapy and Podiatry, Universidad de Sevilla, C/Avice-na s/n, 41009 Seville, Spain; (I.E.-M.); (I.C.P.-T.); (J.M.C.-L.); (G.D.-M.)
| | - Gabriel Domínguez-Maldonado
- Department of Podiatry, Faculty of Nursing, Physiotherapy and Podiatry, Universidad de Sevilla, C/Avice-na s/n, 41009 Seville, Spain; (I.E.-M.); (I.C.P.-T.); (J.M.C.-L.); (G.D.-M.)
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