Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40623-020-01282-3/MediaObjects/40623_2020_1282_Fig2_HTML.png)
Depth results estimated by the NDC of largest eigenvalue of structure tensor with different normalization functions, and the standard deviation in the Gaussian envelop is \(\delta x = \delta {\text{y } = \text{ }}0.01\). a By arithmetic mean; b by median; c by geometric mean; d 3D view of the normalized result by median