Correlation score map for each regression and estimation method, and the
pipeline method. Correlation scores from each method are 0.9151(Top left, Linear
regression with Length), 0.9447(Top right, Length x Depth estimate),
0.9817(Bottom left, Linear regression with Length, Depth, and Thickness),
0.9848(Bottom right, the pipeline method with deep learning). The pipeline
method shows the highest correlation score among the volume measurement
methods.