Methods and algorithms for video-based multi-point frequency measuring and mapping

• Simultaneous multipoint measurement of vibration frequency.
• Calculation and display of a frequency map over a scene.
• Time–frequency analysis of video sequences.
• Analysis of complex-object’s vibration at a glance.
• Free access to main algorithms.

Object vibrations and movements can be detected through changes in its luminance. In this paper, we demonstrate that we can obtain the vibration frequency of all vibrating targets in the sequence simultaneously through the analysis of local neighborhoods. The study is completed with a short-time Fourier analysis so that changes in the movement frequencies are also accounted. We also show that this information can be displayed like a color frequency map that can be superimposed to the video sequence providing a whole description of the analyzed sequence. The method can be used to analyze complex structures since their different vibrating parts can be visualized at a glance. The main algorithms, methods and some sequences are freely downloadable so that new applications and procedures can be implemented by the scientific community.

Color map showing the vibration frequencies of the different parts of a pedestrian bridge. Notice the cable, deck and vertical beam vibrating at 10, 13 and 19 Hz respectively.Figure optionsDownload as PowerPoint slide