No abstract

This paper presents a novel methodology to combine ambient vibration-based operation modal analysis with three-dimensional ground-based lidar data to study damage on the Nyatapola Temple, which is a Bhaktapur UNESCO World Heritage Site that was damaged during the 2015 Gorkha, Nepal, earthquake. The post-earthquake ambient vibration data, collected via accelerometers placed on various levels of the temple, are used to estimate the vibrational properties via operational modal analysis. These properties are then compared to the pre-earthquake dynamic characteristics collected in 2002. The lidar data provide a geometric assessment of the current condition of the temple, capturing post-earthquake drift as a function of height as well as significant cracks present in the facade. The lidar data also inform the numerical models implemented for the post-earthquake condition assessment of the temple.

No abstract

Abstract. Multi-view camera systems are used more and more frequently for applications in close-range photogrammetry, engineering geodesy and autonomous navigation, since they can cover a large portion of the environment and are considerably cheaper than alternative sensors such as laser scanners. In many cases, the cameras do not have overlapping fields of view. In this paper, we report on the development of such a system mounted on a rigid aluminium platform, and focus on its geometric system calibration. We present an approach for estimating the exterior orientation of such a multi-camera system based on bundle adjustment. We use a static environment with ground control points, which are related to the platform via a laser tracker. In the experimental part, the precision and partly accuracy that can be achieved in different scenarios is investigated. While we show that the accuracy potential of the platform is very high, the mounting calibration parameters are not necessarily precise enough to be used as constant values after calibration. However, this disadvantage can be mitigated by using those parameters as observations and refining them on-the-job.

No abstract