Abstract
This article compares the techniques used for camera positioning in a study room, proposing optimized data collection for three-dimensional analysis. This study analyzed the usable recording volume of three different video camera layouts: six equidistant cameras (C6), 8 equidistant cameras (C8E) and 8 cameras using enhanced positioning techniques (C8EP). In the last configuration, we attempted to place the cameras in certain locations in the room so that they had the same capture volume. It was observed that the volume of the 8 equidistant camera layout remained practically the same as that using the 6 camera layout (C6=10.579 m³ C8E x=11.565 m³). Regarding the enhanced positioning layout (C8EP), a 37% gain in usable walkway length was obtained, along with a 14% gain in width, 34% in height, and a consequent increase of 110% in total volume (22.247 m³). Although most modern kinematic analysis software have tools that are able to fill in the markings trajectory, the enhanced positioning camera layout provides more accurate information and data interpretation, besides ensuring better usage of rooms with restricted dimensions. The considerable gain in vertical dimension allows for the evaluation of performed activities at a higher level, such as those involving the upper limbs or steps.
Highlights
The Kinematic analysis of gait using three-dimensional analysis laboratories utilizes a system of cameras in standard fixed positions that capture the movement of reflective markings attached to the skin of the individual, forwarding it to a computer in order to create threedimensional movement simulations, models and visualization of real movements in a virtual environment
Since the dimensions of the study room were already fixed and there were eight available cameras, the challenge faced by this study was to optimize the capture environment to be able to view a 10.59m2 walkway
The positioning of cameras was based on markers on the floor, this strategy proved useful to optimize assessment of human gait once this study’s usable volume was increased due to enhancement of linear measurements in all three dimensions: laterolateral, anteroposterior and in the height in the alternative 8-camera arrangement
Summary
The Kinematic analysis of gait using three-dimensional analysis laboratories utilizes a system of cameras in standard fixed positions that capture the movement of reflective markings attached to the skin of the individual, forwarding it to a computer in order to create threedimensional movement simulations, models and visualization of real movements in a virtual environment. There should be a sufficient number of properly positioned cameras so that all markings may be seen at all times by at least two of the cameras When this condition is not met even on short sections of the walkway, more modern movement analysis resources should be used that have an interpolation tool, which fills in the markings trajectory in those sections by way of simulation and animation based on mathematical algorithms [1]. Depending on the room size, the cameras should be arranged as far as possible from the walkway, so as to increase the range of view that will capture the movement of the markings, given the markers’ size is large enough to be visualized [2,3]. Improvement of gait capture only requires adequate length and width, such motion analysis system may be used for vertical movements too, an improvement in height is desirable
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