In view of the building collapse in Surfside, FL, and subsequent action by the State legislature (Florida Senate Bill 4D), many stakeholders, namely high-rise building owners, property management companies, building officials, engineers, and insurers, will need to document the existing conditions of structures.
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Drones have already proved to be valuable in search and rescue operations, and after hurricanes, earthquakes, and similar natural disasters. They also play a major role in structural evaluation.For consultants, drone surveys help in a detailed and thorough evaluation of structures. They aid in reducing report preparation time, categorizing the type of damage, determining the quantity and location of damage, providing evidence for expert witness testimonials, as well as optimizing project portfolio, marketing, and advertising. For property owners, they can be important in justifying maintenance and repair expenses and supporting insurance claims. Even contractors can benefit, from documenting pre-construction conditions and construction progress to providing as-built documentation (rebar, PT cables, utility piping layout in slab before concrete pour) and defending legal actions.A drone survey of a typical building can generate over 100 GB (Gigabyte) of data including thousands of images and videos. Systematically viewing, sharing, and storing this data is a major challenge.

This paper will discuss the pros and cons of video versus high-definition still images, how to manage a vast amount of collected imagery, and how to view and share images on demand using different platforms (computers, tablets, or phones).

Capturing images using drones is an art! Besides flying skills and knowledge of drones, a drone operator should have good knowledge of photography and videography. The quality of video recording is subject to the type of camera shutter (electronic vs mechanical), frame rate, camera steadiness, and smoothness of panning. Video images tend to be of lower resolution than still images, and they have more compression noise. Also, electronic shutters often produce distortion called rolling shutter. This is also known as “The Jello Effect”

Therefore, video recording may be convenient but not very practical for capturing details. During video recording, the drone is moving continuously. In any given video, one must watch the entire footage to pinpoint a location of interest; and there are often several videos of each structure to watch. This requires tedious time-tagging by someone who is both familiar with the structure and good at problem identification. In reality, videos are best suited for real estate professionals to highlight structures in relation to their surroundings for prospective buyers.

It is important to stress that the flight time of all drones is limited by battery life. Thus, it is critical that each flight is well planned and executed to acquire the maximum information possible.

Many drones today have the built-in capability of producing panoramas from a collection of high-resolution still images, captured while rotating a drone 360 degrees. Each image also contains data such as ISO, exposure, GPS coordinates, and altitude

As explained before, still images have the unique advantage of being easy to index. Innovative image management systems automatically catalog drone data as illustrated in the example below. Figure 3 shows a sample site located on the intercoastal waters in South Florida.

The site was imaged with a drone on two consecutive days. Figures 4 and 5 show the locations of the drone flights.

At each of the locations, a drone was flown to various heights, and at each height, a panorama was captured. A drone is always oriented towards the structure to lock in the exposure of the camera. This avoids wash-out or darkening of the subject. To access a panorama at a specific height, one clicks on any blue tag and selects the height from the pop-up table (Figure below).