Your digital video camera may have the ability record video in several different aspect ratios. This setting may adversely affect video analysis in Logger Pro software.

First a review of Logger Pro’s video analysis features: During video analysis, Logger Pro records the x and y coordinates of points on a video. These coordinates are initially recorded in screen pixels. Setting the scale allows Logger Pro to convert pixels to a physical unit such as meters. Logger Pro assumes that the video pixels are square so that the conversion process applies to the analysis of both horizontal and vertical motion.

Your digital video camera may have the ability to change the aspect ratio. For example the default ratio might be 4:3, but you might be able to set it to 16:9, or widescreen. It may turn out that changing to a different aspect ratio alters the pixel dimensions in your video, and the resulting pixels may not be square. The video will rely on the display device, such as a widescreen monitor, to correct for the non-square pixels. The expansion of pixels is called “anamorphic” correction. When viewed on a computer, the widescreen video may be compressed horizontally into a standard square-pixel, 4:3 aspect ratio image. If this happens, quantitative two-dimensional video analysis will be impossible. A simple test will let you know if this is happening when you switch aspect ratios. Set your camera to the new aspect ratio and record a video of a square object such as a piece of paper. Import the recorded video to your computer and view it using Quicktime or Logger Pro. Does the object remained square? If it did not, you cannot use this aspect ratio setting when recording videos for video analysis.