9Measurement of concrete strain through non-invasive methods is of great importance in civil 10 engineering and structural analysis. Traditional methods use laser speckle and high quality 11 cameras that may result too expensive for many applications. Here we present a method for 12 measuring concrete deformations with a standard reflex camera and image processing for 13 tracking objects in the concretes surface. Two different approaches are presented here. In the 14 first one, on-purpose objects are drawn on the surface, while on the second one we track small 15 defects on the surface due to air bubbles in the hardening process. The method has been tested 16 on a concrete sample under several loading/unloading cycles. A stop-motion sequence of the 17 process has been captured and analyzed. Results have been successfully compared with the 18 values given by a strain gauge. Accuracy of our methods in tracking objects is below 8 m, in 19 the order of more expensive commercial devices. 20 21 22
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.
We have designed a configurable stand-alone Matlab-based software to simulate dichromatic perception of video streams. The algorithm used is an extension for video streams of the "corresponding pair algorithm" by Capilla and coworkers for simulation of dichromatic perception of images. The software allows the user to upload a video sequence and to process it using different dichromatic color vision models and viewing conditions. The output video may be generated in different spatial and temporal resolutions and file formats. The functions for Matlab environment and a stand-alone application may be downloaded from the Repository of the University of Alicante.
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