5 Replies Latest reply on Jun 1, 2014 7:21 AM by eiknachui

    Help needed with applying a track matte

    eiknachui Level 1

      hi.

       

      i'm trying to apply a track matte for the first time. i'm using this article http://www.adobepress.com/articles/article.asp?p=2039925&seqNum=2 as a guide but instead of only 2 footage layers i also use a shape layer - I want to create a "hole" in the top footage so that the contents of the bottom footage could be visible through it. So my layer stack has this order: 1. Shape Layer 2. Top Footage 3. Bottom Footage. On the Top Footage I applied "Alphe Matte Shape Layer" but instead of seeing a part of the Bottom Footage through the Shape Layer, the whole Bottom Footage is shown on the screen. Just to be sure, i tried to change the order of the layers and also tried Alpha Inverted and Luma mattes, but did not achieve the result i want. What is wrong with this composition?

       

      track matte.jpg

        • 1. Re: Help needed with applying a track matte
          Rick Gerard Adobe Community Professional & MVP

          What does your shape layer look like when you turn on visibility? What is the opacity of the Shape Layer

           

          When presenting a comp for troubleshooting please select the layers in question and press the u key twice to reveal all properties that are not at the default settings. This will give us a clue. Here's a normal track matte setup using a shape layer.

           

          Screen Shot 2014-05-31 at 4.27.23 PM.png

          • 2. Re: Help needed with applying a track matte
            eiknachui Level 1

            when i turn on Shape Layer's visibility it looks like a blue rectangle frame. Opacity is set to 0%. When Opacity of the Shape Layer is around 50%, the Top Footage contents are visible within that rectangle frame. When Opacity is 100%, only a Fill color is displayed.

             

            trks.jpg

            • 3. Re: Help needed with applying a track matte
              eiknachui Level 1

              SOLUTION: i placed the Bottom Footage above the Top Footage and selected "Alpha Matte Shape Layer 1" and got the result i wanted. So, this is the other way around of how i understand this statement: "The underlying layer (the fill layer) gets its transparency values from the values of certain channels in the track matte layer—either its alpha channel or the luminance of its pixels " . So, the underlying layer (the Top Footage in my comp) should have gotten its transparency values from a track matte above - and if the track matte above is a small rectangle (with 0% opacity) this rectangle should have cut a transparent hole in the fill layer below? Plus, on the underlying layer below a track matte there was selected "Alpha Matte Shape Layer 1" which means (correct me if i wrong) that the layer below the track matte accepts transparency information from a matte above?

               

              In my project, only a small part of the Top Footage should have been transparent so that a part of the underlying Bottom Footage's contents could be visible. I though it to be logical to place the Top Footage above the Bottom Footage but i achieved the result i wanted with placing the Bottom above the Top.

               

               

              solved.jpg

              • 4. Re: Help needed with applying a track matte
                Rick Gerard Adobe Community Professional & MVP

                In this example your shape layer has an opacity of 0.

                Screen Shot 2014-06-01 at 3.55.18 AM.png

                This means that the are no pixels to use as a track matte. Turn the opacity to 100% and you'll have your track matte and it will effect the layer directly under it. The Bottom Footage layer is apparently the footage of the man judging from the image comp that works. In the comp that shows opacity of 0% setting the track matte to Invert Alpha would have cut a hole in the footage of the Building. Either approach would have worked if the opacity of the layer was set to 100%.

                • 5. Re: Help needed with applying a track matte
                  eiknachui Level 1

                  thank you for the explanation about the track matte's Opacity role. So i placed the Top Footage (a building) over the Bottom Footage (a man), set Shape Layer's Opacity to 100% and applied "Alpha Matte Shape Layer 1" on the Top Footage i got the following result (the Top Footage contents being displayed in the Shape Layer's rectangle, and the Bottom Footage covering the rest of the screen) :

                   

                  BLET.jpg

                   

                  If I apply "Alpha matte inverted" on the Top Footage then i get the result i want. Honestly, this is really confusing. Does it have something to do with the footage I'm using? The Bottom Footage is .avi, while the Top Footage is .f4v