URL https://www.researchgate.net/publication/369379726/figure/fig3/AS:11431281128436776@1679369746594/Illustration-of-an-a-FDT-filter-The-x-axis-stands-for-the-spectrum-with-each-sample_Q320.jpg
URL2 https://www.researchgate.net/figure/An-example-of-tangent-bundle-signal_fig2_369379726
