Analytical study of distance variable according to the difference between the location of the Drawing scale and the performance in moving away and approaching the camera

دراسة تحليلية لمتغير المسافة وفقا للفرق بين موقعي مقياس الرسم والاداء في الابتعاد والاقتراب عن الة التصوير

Abstract

Photography is the basis in the process of analysis of sport movements so it was necessary for researchers to master the process of photography to adjust the variables that are designed to extract, especially the variable distance, which depends on the measurement of the existence of a real drawing scale. Many researchers may commit a mistake in the location of drawing scale due to moving away or approaching camera, which gives a percentage of error in the real values, so you have to find an alternative solution and find a suitable way to reduce the error in the scale. The study aimed to identify the percentage of error at the location of the scale of the drawing on the location of the performance in moving away and approaching from the camera, and find an alternative solution to address the error in measuring distance. The procedures were summarized by photographing a 2-meter and 2.05-meter display in five different positions from the camera within a 2 x 1 m rectangle with a drawing scale in the middle of the rectangle. The length of the screen is then extracted and displayed at each location according to the real scale located in the middle of the rectangle and the error percentage will be identified., then the height of the figure is  re-extracted again according to the proposed method ,which is to use the rectangle as a measure of drawing where the screen is adopted to extract the scale of drawing by drawing a line between the sides of the rectangle, which is 1 meter (width) and identify  the error percentage. The results showed that there is an error percentage at the different location of the performance of the site of the scale of drawing in moving away and approaching the camera, which begins to increase the value of the real measurement as you approached the camera away from the scale of drawing, and vice versa begin to underestimate the real measurement once it moves away from the camera and the scale. As for the proposed method, there was a very small error percentage for the real measurement in all five locations. This is why we recommend using this method in all research instead of the traditional drawing scale to ensure more realistic values ​​when the location of the performance is different during filming