Alberto Pellegrinelli

Measurement of surface velocity in open channels using a lightweight remotely piloted aircraft system

ABSTRACT In this paper, a low-cost remotely piloted aircraft system (RPAS) technique is proposed for measurement of the surface velocity in rivers or channels with low surface velocity and small discharge. To verify the reliability of the results obtained with the RPAS, we simultaneously measured the surface velocity with other methods based on total stations and close range photogrammetry. The RPAS was used both with ground control points (GCPs) for orientation of the photographic images and without GCPs. The data analysis showed that the RPAS provides valid results even without GCPs. Use of a RPAS without GCPs, relying solely on flight altitude to determine the water velocity, opens the way for its utilization in emergency conditions when it is impossible to access the river banks for the realization and survey of GCPs.

Motorised digital levels: development and applications

Abstract A low-cost motorisation of the Leica DNA03 digital level was designed to enable the automatic monitoring of deformations without compromising its manual use in levelling. The upgrade of the instrument and its electronic control system are described together with laboratory tests carried out to study the effects of ambient temperature on the level. A simple model for the correction of measurements as a function of the temperature is proposed. The detection of vertical movements with sub-millimetre accuracy was obtained in a simulated permanent monitoring system. The operational advantages of the instrument are shown in a field test. Despite the encouraging results, research is still needed to find a reliable model for the correction of the staff readings under changing temperature conditions.

A new approach to obtain metric data from video surveillance: Preliminary evaluation of a low-cost stereo-photogrammetric system

Using an interdisciplinary approach the authors demonstrate the possibility to obtain reliable anthropometric data of a subject by means of a new video surveillance system. In general the use of current video surveillance systems provides law enforcement with useful data to solve many crimes. Unfortunately the quality of the images and the way in which they are taken often makes it very difficult to judge the compatibility between suspect and perpetrator. In this paper, the authors present the results obtained with a low-cost photogrammetric video surveillance system based on a pair of common surveillance cameras synchronized with each other. The innovative aspect of the system is that it allows estimation with considerable accuracy not only of body height (error 0.1-3.1cm, SD 1.8-4.5cm) but also of other anthropometric characters of the subject, consequently with better determination of the biological profile and greatly increased effectiveness of the judgment of compatibility.

Integrated Measurement Techniques for the Monitoring of the Ancient Walls of Ferrara

The ancient walls surrounding the historic center of Ferrara for 9 km almost uninterrupted, create one of the most impressive defensive systems of the Middle Ages and the Renaissance. The earthquakes of May 2012 increased the instability of the bastion of “Sant’Antonio” in the south walls, in fact, existing lesions are evidently grown. In order to preserve this historical and artistic heritage a complex monitoring system, based on the integration of various surveying techniques was realized. At the base of the structure a high precision geometric leveling network has been materialized to determine the vertical component of displacements, indeed on the top have been set up targets to determine by total station the planimetric component of displacements. Finally, we used TLS (Terrestrial Laser Scanner) to rate global variations of wall shape and some crack gauges to monitoring the main lesions. From the first repetitions of surveying with the described techniques, we remark a progressive increase of the framework deformation and an interesting agreement of the results.