masking gives me a line

sbradysbrady Website User Posts: 28

why do I get a line around the thumb when masking. Some frames it is there, some frames it is not there.  Got a deadline dontchaknow.masking line

Comments

  • tddavistddavis Moderator, Website User Posts: 4,186 Moderator

    @sbrady Not sure why exactly it's got the line, but have you tried fiddling with the feather on the mask to blend it together and maybe remove the line?  I think by default it feathers both sides of the mask but I think the strength is low or none existent by default.  I can't recall.  Just a thought.

  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,442 Enthusiast
    edited February 2017

    You can get a line if you apply a Mask to one layer, duplicate it, then invert the Mask on the second copy. It's a way to allow you to insert something behind a masked object fairly easily by putting it between the two layers and having (in theory) no holes anywhere.

    But the Masking maths isn't 100% accurate, so you do have to feather one of the masks to get rid of that line. Can't remember which; so experimentation will reveal all... ;)

  • sbradysbrady Website User Posts: 28
  • sbradysbrady Website User Posts: 28

    when I feather, I get a dark line......what dark, the image is a white shirt.

  • TotopoCraftTotopoCraft Website User Posts: 194 Just Starting Out

    What if you add some pixels of expansion to the mask?

  • tddavistddavis Moderator, Website User Posts: 4,186 Moderator

    @sbrady  Did you ever get your issue with the dark line solved?  If not, and you are still working on it, I had another thought of something to try.  I ahve seen lights added to a scene affect the layers if the properties for shadowing are checked.  Is it possible that is a shadow of the thumb layer above the main video layer and it's casting shadows?

  • sbradysbrady Website User Posts: 28

    I don't think so, I don't have a light on that layer.  I fiddled around a lot, seems to be working now and I'm not sure what I did. I'm a newbie so chalk it up to I don't know what the hell I'm doing yet.

  • tddavistddavis Moderator, Website User Posts: 4,186 Moderator
    edited February 2017

    @sbrady. Well, the main thing is you got it sorted.  And about finding the answer without knowing what you did I'm sure we've all done that one time or another.  I know I certainly have!  :)

     

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,302 Ambassador

    @sbrady @Palacono @Emecorp I'm late to the game, but I suspect the initial issue is a simple antialiasing thing. I'm pretty sure masks in Hitfilm get automatically antialiased, which could actually cause a pixel of translucency when the two mask edges are supposed to fit like perfect puzzle pieces (Palacono, this would not be a bug or a maths error).

    sbrady, I suspect your fix was probably 1 or two pixels of expansion, feathering or both.

  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,442 Enthusiast
    edited February 2017

    @Triem23 it even happens with rectangular masks, so whether antialiasing is the reason or not on straight lines, it's still a (minor) pain in the rear. 

    An expansion of between 0.5-0.7pixels fixes it.

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