Software-Based Three-Dimensional Surface Imaging and Scanning in Plastic Surgery

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I greatly enjoyed the informative and well-written article by Weissler et al. entitled “The Evolution of Photography and Three-Dimensional Imaging in Plastic Surgery.”1 The authors helpfully outline clinically meaningful applications of three-dimensional photography in plastic surgery, and discuss the use of specialized photographic equipment designed to capture these images.
The authors raise the issue of cost, noting that the expense of three-dimensional capture systems is one of the greatest barriers to the widespread adoption of this technology. They highlight the availability of several capture systems ranging in cost from $1000 to $30,000.
An important addition to this range of options is newly available software that generates three-dimensional images using stereophotogrammetry from a series of photographs captured by any camera or smartphone. No specialized equipment is required, because the software is able to generate a robust three-dimensional image from a series of several dozen to several hundred still images taken at various angles. By relying on triangulation,2 a true three-dimensional mesh can be created without additional hardware.
ReCap 360 (Autodesk, Inc., San Rafael, Calif.), a free cloud-based image processing system, was used to perform a sample three-dimensional reconstruction using a series of 64 facial images taken with an iPhone (Apple, Inc., Cupertino, Calif.). Ideally, photographs at several heights are captured with a minimum of 40 percent overlap. Depending on the number of images used to create the model, a full 360-degree, three-dimensional, photorealistic model can be created (Fig. 1). (See Video, Supplemental Digital Content 1, which shows a three-dimensional video recreation captured using passive software-based stereophotogrammetry that requires no specialized equipment,
The fidelity of the three-dimensional image created with this system is outstanding, as the sample scan yielded 913,795 vertices, which compares favorably to the resolution of scans created using structured light sensors.3 Another advantage of software-based stereophotogrammetry is its portability. Because no special equipment is needed, surgeons can use this technology in satellite clinics and when working in medically underserved areas. With minimal training, patients may be able to capture image sets of sufficient quality to permit remote analysis by their surgeons.
Limitations of a cloud-based approach include possible privacy concerns and the unpredictable time required for scan processing because of queuing, which varies based on server availability and load. Both of these concerns may be entirely mitigated by using local computer-based software for rendering such as ReMake (Autodesk), which is available in both free and paid versions. Software-based passive stereophotogrammetry provides an essentially free option to surgeons interested in incorporating three-dimensional imaging, and future software development and workflow optimization may make these systems even more useful, permitting broader adoption of three-dimensional imaging in plastic surgery.
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