Non-Destructive Analysis of Three-Dimensional Objects Using a Fluid Displacement Method.

Quantification of three-dimensional (3-D) objects has been a real challenge in agricultural, hydrological and environmental studies. We designed and tested a method that is capable of quantifying 3-D objects using measurements of fluid displacement. The device consists of a stand that supports a movable platform to which the sample is attached. The sample is lowered by measured increments into a vat of fluid. In the original model, as the sample was lowered the displaced fluid overflowed into a container on a scale that sent the weight to a computer. While this worked, the surface tension limited accuracy and it was very slow. To improve the process, the fluid was contained and the fluid level was measured with a linear variable displacement transformer. The displaced fluid volume for each increment and the immersion depth is recorded by a data logger.  The surface area of the fluid is reduced as the sample is immersed, so calculations are performed to account for this change. The apparatus was built to facilitate the characterization of three dimensional objects for shape and volume comparisons. It has numerous agricultural and environmental applications. It has been used at our location to quantify the size and length of soil macropores in field soils. It has also been used to numerically evaluate the taper of sugar beet roots. The apparatus produces good estimates for both aforementioned soil and plant applications.