after I use ctrl to mask part of an object then press extract button under subtool, the result is strange. Along the edge, there’s all the noise, dots…
Did I do anything wrong or that’s how it works?
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after I use ctrl to mask part of an object then press extract button under subtool, the result is strange. Along the edge, there’s all the noise, dots…
Did I do anything wrong or that’s how it works?

You are using ZBrush 3.12. That version is way out of date and you should upgrade to ZBrush 4 - free for registered users.
Oh Thank you