Volume and area: A computacional measure

Area and volume measurements are fundamentals in heat and mass transfer modeling studies. It is necessary to measure them and usually they are obtained based on the live body weight of animals. This methodology is valid only for a specific dataset. It was obtained from a specific group of animals and regression equations were estimated. To apply in current animals it brings several errors, once the sampled animals are not the present population. In this study, a computational 3D model was developed to calculate area and volume of simple and complex objects, including humans. It was used two different ways, free versions of photogrammetry software's like Autodesk Memento(R) and Autodesk 123D catch(R). The second was a scanning software like Microsoft 3D scan(R) and 3Dbuilder(R) or Reconstructme(R) associated with Kinect Xbox(R) and netfabb(R) (available version). For the photogrammetry, the objects were put in a place under good illumination and pictures with a good resolution (minimum of four megapixels) were taken around of the objects. They were transferred to computer`s software. The software (Autodesk Memento(R)/Autodesk 123D Catch) converted the images on a 3D model. For the Kinect(R), after installed and plugged on the computer, the Kinect(R) was moved around the objects or the objects were turned and the Kinect(R) remained fixed (better situation). The results indicated that both methods can be used to build 3D models of complex objects like humans or animals showing errors less than 3% for the objects measured. For standard object like a box or cylinder the results showed an error of 2.17% and 1.33% for area and volume, respectively. This can be explained by the format of the scanned object, which are not completely regular, and the manual calculation of a rectangle (box - 16x35x7.5cm), for example, takes into account the perfect sides of it. However to apply the techniques for animals, it is necessary to train and to keep them in a stable position. In this case, the photogrammetry is the easiest way. It is not necessary to revolve the animal or the object. Therefore, the measurements through computational 3D modeling can be an alternative and effective method to calculate the area and volume of complex objects noninvasively.