Smoothing Recursive Gaussian Image Filter

Slicer version:4.10.1
Hi 3D Slicer experts and all
I used Smoothing Recursive Gaussian Image Filter from simple filters module. My input volume is a CT image and I chose various sigma values, which in the below figure, the result of this selection in each row, have been shown. (σ1= 3, 0.0001, 0.0001 / σ2= 0.0001, 3, 0.0001 / σ3= 0.0001, 0.0001, 3).
I can’t distinguish each of this σ values affect on which view (axial, sagittal or coronal). In the other words, what is the difference among σ1, σ2 and σ3 ?
Also, along which axis or on which view ( axial, sagittal, or coronal) does σ1 have the greatest influence?
Thanks a lot

Hi 3D slicer experts and all
Unfortunately, I didn’t receive any feedback. In Smoothing Recursive Gaussian Image Filter, I selected different values for Sigma. Finally, I find that for Sigma with three components (a,b,c), it seems that if a>> b and c , the Sagittal view is the sharpest. Also, for b>> a and c; Coronal view is the sharpest and for c>> a and b, Axial view is the sharpest (like the below figure).
So, can we conclude that “a” component has the most smoothing on L-R axis, “b” component on A-P and “c” component on S-I? In other words, do the “a, b,and c” components have the most smoothing on RAS, respectively?
Thanks a lot

Yes, what you describe is correct, and it is so because Slicer uses RAS coordinate system.