# A Review of Commercially Available 3D Surface Imaging Systems for Body Composition Estimation
## 4 Discussion
### User Details  
The commercially available 3D surface imaging systems reviewed in this paper reported minimum and maximum user height and weight of 0 (none) to 213 cm, and 0 (none) to 272 kg, respectively. This demonstrates that commercially available 3D surface imaging systems that estimate body composition can easily accommodate a variety of body sizes, unlike alternatives such as DEXA [30].  
However, the validity of body composition estimations for different sizes, ethnicities, and races remains unknown, as few system manufacturers reported details regarding the population sample upon which their body composition estimation predictive algorithms are based upon, and of those that do, the majority use predictive algorithms based upon military personnel such as Hodgdon & Beckett [31] and [PERSON] et al. [22]. Furthermore, three system manufacturers; Fit3D, Naked Labs, and Styku, report developing their own proprietary predictive algorithms using DEXA for body composition estimation through partnerships with research groups, universities, and medical facilities. This is of concern when exploring the potential validity of systems for all, as it is suggested that DEXA demonstrates a scaling error when body size increases [32] and--as an indirect method--is also an estimation [33]. It is also worthwhile to note that, for system manufacturers that have their own proprietary predictive algorithms, they are often continuously developed and updated alongside their humanoid mesh and anthropometry code--as outlined on the Fit3D website; \"As Fit3D aggregates additional and statistically relevant sets of data, we will continue to revise our body fat algorithm to ensure that we are providing the most accurate assessment of body composition possible through anthropometric measurements... As Fit3D publishes its research and updates/upgrades its models, we integrate the research and models into the product\" [23]. Thus, whilst this may result in more representative algorithms, it is vital to know which version of the algorithm is used, as it is possible algorithm updates may occur between uses, thereby impacting comparison and anthropometric surveying.  
All system manufacturers reported a minimum user age, ranging from 2 to 18 years, demonstrating that commercially available 3D surface imaging systems that estimate the body composition of children and young persons are available. This is advantageous as there is an increasing volume of research recommending the use of 3D surface imaging systems on children [13; 14; 16; 34; 35]. The potential usefulness of this technology for regular use with children and young persons is exacerbated by the unsuitability of existing body composition estimation methods for children--such as DEXA, due to its cost and use of ionizing radiation, as discussed by [PERSON] et al. [36]. However, to the researcher's knowledge, no system manufacturers provided child specific guidance, packages, or evidence of the accuracy of body composition estimations when measuring children or young persons. This is of concern as it is suggested that the potential usefulness of this technology with children and young persons is reliant upon child specific guidance and predictive algorithms [16; 37].