Need help: Output mask artifacts - Can't get rid of them

Hello WM’ers,
So I have this annoying ‘artifact’ / ‘ghosting’ thing happening on my Output masks that I’m importing into UE4. The issue is clearly with WM and not UE4; I only attached the UE4 screenshots to further illustrate the issue.

First pic, as you can see, the ghosting is occurring to the right of the main mask.
Second pic is screenshot in UE4.
Third pic is screenshot of overhead in UE4.
Forth pic is a screenshot of WM Device View.

I have been working with this for about a month now, and just can’t seem to pinpoint the origin. I’ve tried multiple output methods, starting over from scratch, I even deleted and reinstalled WM, all with the same results. If you have had this issue and fixed it, or have some insight, please advise. Thank you for reading.


Wm masks tend to be smooth around the edges, which creates problems when exporting to engines that have optimizations in engine that handle alpha differently, especially when you export masks in an 8 bit format. Try to keep your masks at 1 and 0, no halfway greys. You can get away with small amounts, thin bands, for smooth transition. Use bias/gain device for cleaning up the mask. I don’t have extensive knowledge of how UE handles alpha, but this is a common problem all around.

Thank you for the reply, WFab, it caused me to re-think my entire strategy. I did some experimenting with Bias/Gain, multiple selectors, but no change. It turns out, the Clamp node that’s used to Normalize the terrain was the culprit (there is a warning that comes with the node referencing tiled builds). Is there a substitute for the Clamp/Normalizer that works with tiled builds? Now the terrain is relatively flat compared to Normalize turn on.

You can again use Bias/gain device to manually tweak the height and contrast. That shouldn’t create problems with tiled builds.