There may be another way to do it but usually stair stepping is caused by aliasing, I usually add a soft, subtle blur to the edges of anything being used as a heightmap and it takes care of it.
That being said I'm new to substance so if anyone has another suggestion please post.
Thank you chrono1081 so helpful to know the blur tip

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i posted the same subject on the designer discussion section of the forum ,so maybe someone not interested in the contest may help, but they respond that the shape is too hard to pull off , that's why i didn't make it for the contest deadline ,cause i was trying to pull off this shape accurately over and over again ,i didn't want to change the entry , it should be a good exercise

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and just to let you know the issue was resolved by switching from tessellation mode to parallax occlusion , i myself being new to substance ,
i didn't even understand when we should use either tessellation or parallax because each mode seems to work properly than the other for each scene i created .
Though i'm still struggling to achieve the right smooth transition in height from the higher part towards the lower part which is the heart shape , in addition to creating the heart shape carved into the surface ,
so any suggestions would be appreciated

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