I was trying to generate a contour line for small and large area . First I decided to try with the small area. I mosaicked the different DEMs and then project it to UTM after that, I tried to generate contours with different contour intervals and there are very noisy contours in all the intervals I used ( 10,20, 50 & 100). Just as an eg I have attached the 20m interval. What can I do to improve the noise? I tried by smoothing the DEM and not as such improved any advice or what I made wrong?