Fish-Eye warp gets parts of picture outside of mask

eTVeTV Website User Posts: 44

Hi,

I have a peculiar problem. It seems like even though I have created a mask, where I expect my warped picture to be inside - I get some weird parts that are coming outside of the mask.

To recreate:

I have first created a plane in one color. 

On top of this one another plane in a different color with a mask so I get to see the plane below.

On top of this second plane I have  a picture (doesn't matter if it is a video). This picture I have created a fish-eye warp effect to. Then re-sized it to about 12% and placed it on top of the area where I have the mask in the second plane. A mask is then drawn with the Freehand tool. 

I then expect that the picture should be within my mask, but possibly due to the Fish-eye warp some parts end up outside.

The example here is quite basic. I first encountered it when masking out a rear view mirror in a car shot on a green screen in order to simulate that  the mirror showed the traffic in the rear.

Any ideas on why this is happening? And how do I post a picture that illustrates the issue?

Comments

  • eTVeTV Website User Posts: 44

    Ok  -still have no clue on how to publish any pictures here. I have illustrated the issue in the following video. I know, not the most beautiful work of art, but more as an illustration.

    Any tips anyone?

    https://youtu.be/XTmBuoLKEU0

  • Aladdin4dAladdin4d Moderator Website User, Imerge Beta Tester, HitFilm Beta Tester Posts: 2,509 Enthusiast
    edited September 2015

    I don't have a full technical explanation as to the why but what you're seeing outside the mask is where fish-eye warp is wrapping the image. In the effect controls setting Wrap X and Wrap Y to No will remove it.

    EDIT: To display an image you have to post it on a service like postimage.org or Flickr first then insert the link into the source property of the insert image dialog. 

  • eTVeTV Website User Posts: 44
    edited September 2015

    Thanks mate for the tips regarding the wrap x and y. The trick solved my issue, although I still have troubles understanding how something can end up outside the mask. 

    Also a big thank you for telling on how to post images in this forum. It wasn't that obvious from the post "Forum Posting rules"...

  • Aladdin4dAladdin4d Moderator Website User, Imerge Beta Tester, HitFilm Beta Tester Posts: 2,509 Enthusiast
    edited September 2015

    If you look at it a little closer and play with the other controls you can see how the wrap function is wrapping the entire layer including the mask with the boundary limit being what the layer was scaled to which in your case means what you scaled the picture to. If you turn off the mask you can see the area being affected by the warp. 

    Turn the mask on and the excess is hidden but the wrap function will still wrap to the original boundary. In this case the height sets symmetrical limit. 

  • NormanPCNNormanPCN Website User Posts: 3,950 Enthusiast
    edited September 2015
    • "I still have troubles understanding how something can end up outside the mask. "

    One thing to remember is that the mask is not some kind of hard barrier done after the effect is performed. The mask is a parameter input to the effect, along with the frame. What happens for a given effect depends on the exact description/implementation of the effect. For example, some effects by definition draw outside the mask. Drop Shadow and Neon Glow are examples here. So a warp effect like the fisheye is probably doing exactly what is wanted by drawing what it is doing outside the mask.

    When something like this is not what you want, and there are not other options, then you have to apply the mask after effect, which in Hitfilm means using something like and embedded comp and then mask the layer referencing the embedded comp.

     Either way, that Fish Eye with the default wrapping options gives some interesting results that would be shear hell to try and do manually.

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