This paper evaluates the performance of conventional three dimensional digital image correlation (3D DIC).

Three dimensional point tracking (3DPT) approaches over the surface of wind turbine blades and proposes a multi-camera measurement system using dynamic spatial data stitching.

The potential advantages for the proposed approach include: (1) full-field measurement distributed over a very large area, (2) the elimination of time consuming wiring and expensive sensors, and (3) the need for large-channel data acquisition systems.

There are several challenges associated with extending the capability of a standard 3D DIC system to measure entire surface of utility scale blades to extract distributed strain, deflection, and modal parameters.

This paper only tries to address some of the difficulties including: (1) assessing the accuracy of the 3D DIC system to measure full-field distributed strain and displacement over the large area, and (2) evaluating the performance of the dynamic stitching method to combine two different fields.

Within this paper the feasibility of employing an output-only system identification to estimate modal parameters of a utility scale wind turbine blade from optically measured data is determined.