What is a matte

Andersen01498Andersen01498 Website User, HitFilm Beta Tester Posts: 942 Enthusiast
edited February 2017 in Post-production techniques

Quick question, what is the point of a matte and how would I use it in mocha?

Comments

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,303 Ambassador

    Ok, theory time. A map, matte, mask and key are all basically the same thing. A channel (or several channels)  used to define a range of effect. 

    A map defines a range from 0 (no effect on parameter) to 1 (full effect on parameter) 

    Mattes, masks and keys are all maps, but not all maps are mattes, masks and keys. 

    Mattes, masks and keys are all ways of defining an opacity map. A matte or mask might be referred to as a "holdout," which means the matte defines an "ignore me" region. 

    A mask is applied directly to the target layer. A matte is when you use a source layer as a map for a target layer. Traditionally/technically both masks and mattes are created by hand. A key is a procedural way to create a mask. 

    Matte and mask are often used interchangeably... This is fine, don't worry about it. 

    So, in Mocha, a "matte" serves two purposes. First, merely to show you what areas define a layer. This is using "show mattes" and just fills your spline with color. 

    Otherwise, in tracking and roto, mocha assumes the top layer is closest to, and the bottom layer is farthest from camera. 

    When tracking, the matte of any layer above the tracked layer is used as a "holdout" matte--excluded from the track. Perhaps I am trying to track a building, but a person is walking through the shot. Garbage matte the person (a "garbage matte" is just a rough matte used to quickly block an area--in this example I wouldn't waste time doing a precise mask if the person, I would draw a very rough shape) then track the building on a layer below the person, and the person is no longer seen--their motion can't mess up the track. 

    In roto, well, splines still holdout on lower layers, which can simplify certain tasks. Also, in roto, mocha has an export mattes option, which really exports masks... What is actually exported is a layer with masks on it, but this layer is intended to become a matte for another layer. 

    The most important part of this little lecture is how a map defines a range of effect from 0 (none) to 1 (full). You see this all over Hitfilm. Parallax and Caustics both use height maps. Black is lowest, white highest. Set Matte uses varied channels to generate a matte, but a luma matte is black=0=transparent to white=0=opaque. A green channel matte does the same thing, but looking at green, etc. Shatter can use a timing map. Black shatters first, white shatters last. Displacement maps are a rare exception in that they run "-1 to +1" with 50% grey being "0".

     

     

  • Andersen01498Andersen01498 Website User, HitFilm Beta Tester Posts: 942 Enthusiast

    @Triem23 are there any tutorials for using mattes in mocha?

  • WhiteCranePhotoWhiteCranePhoto Website User Posts: 896 Enthusiast

    Imagineer has a rather extensive series of tutorial videos on its web site that I recommend working through. 

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,303 Ambassador

    Andersen01498 I gotta go with WhiteCrane here, and refer you to video tutorials. 

    Here's the thing--you don't use mattes IN mocha, with the exception of upper layers being holdout mattes* when tracking on a lower layer. And that's built in functionality you can't turn off. 

    Mocha CREATES mattes to use in Hitfilm. 

    *The Insert and Remove modules of Mocha Pro use a selected track's matte(s)  to define source area and effect area for those tools, but that's the same as using a "Source Layer" in Hitfilm. 

    Any Mocha tutorial for After Effects  applies to Hitfilm. The only workflow change is, instead of copying Mocha data to the clipboard, you save the data as a Composite Shot to import to Hitfilm. In HFP 2017, for roto data, you just hit "apply" and it goes to the selected layer immediately. 

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