Optical imaging for low-cost structural measurements

For many structures, the easiest first step in trying to understand its condition is to take a good look. Often more detailed investigations are required really to characterise the behaviour and performance, enabling assessment of performance against design models, future repair needs and likely in-service lifetimes. If these investigations could be largely carried out in a similar manner to ‘taking a good look’ using digital still and video cameras, then considerable time and cost savings could be made. By processing images captured this way using specialist image correlation software, the systems investigated can create reliable and accurate measurements that could become part of the civil engineer's toolkit. This study shows that the optical image-based measurement techniques do indeed provide reliable data across a range of typical civil engineering surfaces and can provide both high precision and large area measurements providing useful information about the behaviour of civil engineering structures (in this case bridges), which might be useful for short and long-term monitoring.