A wierd gradient over my result

I did but it has same form.[quote=“marjanmarbouti, post:1, topic:13511, full:true”]
Dear all
I used TanDEM-X data and made a DEM from them. Steps are listed in below:

  1. Interferogram formation
  2. unwrapping
  3. Phase to height
  4. Applying boxcar filter (5 by 5)
    But if you look at my final result, there is a blue gradient over my filtered phase to height. How can I remove it?

@falahfakhri I did but same shape.