8 Replies Latest reply on Jan 12, 2009 2:07 AM by OsakaWebbie

    Something wrong with my Track Matte Key

    OsakaWebbie Level 1
      I'm trying to get a clip of a waterfall to pour "onto" video of the horizon of the turning earth from space (no, I don't have budget for space travel - it's free NASA images) without covering up the earth itself. It should be a really simple application of Track Matte Key, but I must be doing something wrong.

      I have the earth on track 2, the waterfall on track 3 (positioned up a bit so that the water falls from the top of the frame), and the matte on track 6. I tried making the matte in the titler, and when it didn't work, I then tried doing it in Photoshop, but that didn't help. The matte is white with a black gradiant semicircle to match the earth shape - I'm not very sharp in Photoshop yet and couldn't figure out how to fill a selection with color, so I used Delete instead: BG color=white, Ctrl-A, Delete, BG color=black, circle selection tool with 40 pixels of fuzzy edge, select my area, Delete.

      I applied the TMK to track 3, set the Matte to "Video 6", and Composite Using: Matte Luma. But instead of using the shape of my matte, it looks like it is using the luma values of itself - the white waterfall shows up well, but the dark green trees almost disappear, but not quite. (If I click Reverse in the TMK controls, the trees show up great but the whitest parts of the waterfall fade and let the earth show through somewhat.) Click here to see a composite image of screen shots: tracks 2 and 3 with TMK off, track 6 visible, my TMK settings, and the final effect.

      Actually the unintentioned effect is kinda cool, as the waterfall looks like it is coming out of black space, but since the clip is moved up, you can see the line where the translucent trees stop and pure earth shows. If I could somehow solve that, I would be happy to just use the effect the way it is. But it would also be good to know what I'm doing wrong to make the TMK effect do this instead of just following my matte. Any thoughts?
        • 1. Re: Something wrong with my Track Matte Key
          OsakaWebbie Level 1
          I'll try bumping this just once. Any ideas? Or questions for me to answer about my setup? So far I just have it in my video as is - I kinda like the unintentional "waterfall out of thin air" look that I'm getting with it seeming to use itself as its matte, but I have no way to control the line at the bottom, so I can't leave it this way without more tweaking. And since I don't know why it's doing what it's doing, it would be hard to tweak it. It's weird - I have used TMK successfully in the past, although I know it is finicky.
          • 2. Re: Something wrong with my Track Matte Key
            akribie Level 2
            I assume you want the waterfall to go behind the earth at the horizon of the rotating earth.

            Where did you get the earth image from? If you made it yourself, is there an option to have an alpha channel? If so, you could place the earth above the waterfall and the alpha mask would do the job for you. If you used AE for the animation, export in Animation CODEC with millions+ colours to get the alpha channel across.

            If the earth clip is flattened, then you need to create an alpha channel in PPro to do the same thing. Put the earth over the waterfall and create a mask (in PhotoShop or the titler) following the shape of the horizon. Then apply the track matte as you describe, but ideally use alpha not luma.

            A titler mask will automatically have an alpha channel.. In PhotoShop, one way to get an alpha channel is to put the the mask on a layer above the background and delete the background layer (there are neater ways, but this is the easiest to explain quickly).
            • 3. Re: Something wrong with my Track Matte Key
              OsakaWebbie Level 1
              Thanks for the ideas, but I actually want the waterfall to flow a bit over the top edge of the earth, to look like it's pouring onto the earth, not behind it. That's why the matte I made was gradiated and lower than the top of the earth. (But it seems that PPro is ignoring my matte and using the clip itself for the luma matte, for some mysterious reason.

              Although for the future it would ultimately be good to figure out what I'm doing wrong with TMKs, for this particular clip I would be happy to leave it the way it is (the unintentional self-luma-matte effect is actually kinda nice) if I can somehow deal with the sharp change between the uncovered earth at the very bottom and the partially covered earth everywhere else. I can imagine two ways of doing that, but I don't know how to do either one without using TMK (a bit of a catch-22) or creating a custom alpha channel for a video clip, which I don't think is possible (after all, that's what TMK is for):
              (1) Give a gradiated bottom to the transparency of the waterfall clip (so that the change from muted earth to bright earth is not as obvious)
              (2) Use just the lower portion of another copy of the waterfall clip with its current effect, placing it at the bottom of the frame, so that what is now "bright" earth becomes muted like the rest

              Can you think of a creative (but not too time-consuming - this little thing isn't worth a pile of work) way to do either of those? As far as I can think of, without using TMK it seems that I can have either all of a video frame or none of it, not some partial selection. I suppose to accomplish #2 I could vertically flip the second copy of the clip and slide it mostly off the frame, but there might be a bit too much waterfall showing in the middle. (Hmm, make two copies, flip both vertically and one of them horizontally, and slide them to the corners? No, that makes a hole in the middle.) I just can't seem to think of a solution.

              (BTW, you asked where I got the earth image - I'd like to say I launched my own spaceship and took my camera, but the serious answer is NASA - the Goddard Space Flight Center website has lots of great photos, and even HD video, and it's all public domain! That particular one started out as a TIF image sequence - I had previously used AE to make it into an AVI, so for this usage I used PPro to rotate it and slide it down, to show just the view looking west as it slowly spins.)
              • 4. Re: Something wrong with my Track Matte Key
                akribie Level 2
                If you make a black mask on a white background, and fade the edge of the mask, you will get a faded-edged overlay if you then use that image as a mask for track matte using the luma option.

                Stack the layers like this (order important, actual track numbers not):

                V3 = mask
                V2 = waterfall - apply track matte here and set to V3 luma and possibly reverse
                V1 = earth

                Works here.

                I'm still not too sure what your 'earth' looks like. 2D if you are rotating in PPro, I guess.

                Wrapping a NASA image round a sphere using CC Sphere in AE allows you to spin the globe, but needs a full-earth image for best effect. You can add spherised cloud layers using the same method and rotate them at different speeds and apply lights to make the whole thing look even more realistic looking, too.
                • 5. Re: Something wrong with my Track Matte Key
                  Ann Bens Adobe Community Professional & MVP
                  Your waterfall is not in the middle, position should read 360,288.
                  Your anchor point is also off: 360.288.
                  • 6. Re: Something wrong with my Track Matte Key
                    OsakaWebbie Level 1
                    David J: The process you described is exactly what I did - that's why I'm mystified that it seems to be using itself (the waterfall) as the matte for the luma key when it should be using Track 6 in my case.

                    You were asking about my earth video. Yes, it's a simple 2D video, and I didn't do any wrapping around spheres to create it - I'm not nearly that smart. I just took what NASA had already animated for me, and rotated the whole thing (not "rotate" as it what the earth does in 3D, but as in the "Rotation" value in the Motion effect in PPro, i.e tilting the whole video on its side). The one I used for this was http://svs.gsfc.nasa.gov/goto?3404 (to get the best resolution and quality, I like to take the "Frames" option and use AE to make the TIFFs into an AVI), but another one, which doesn't show earth as long but the view it has is more natural-looking, is http://svs.gsfc.nasa.gov/goto?1402 (there is only one short part that is just the earth, but I get some mileage out of it).

                    Ann: Yes, I know my waterfall is not in the middle - I don't want it to be. The top of it is undesirable, so I moved it up. That's why I have a problem at the bottom. But for me the middle is 360,240 - my video is NTSC, whereas you are evidently working in PAL.
                    • 7. Re: Something wrong with my Track Matte Key
                      akribie Level 2
                      In some earlier versions of PPro there were issues with track mattes that were resolved by putting the matte clip into a separate sequence and using that sequence as the matte clip on the main timeline. Worth trying, perhaps.
                      • 8. Re: Something wrong with my Track Matte Key
                        OsakaWebbie Level 1
                        Yeah, I dealt with that issue a little myself, but the problem was when you moved the matte around. My matte was unmodified.

                        Anyway, I played around with it some more - my instance of TMK is definitely acting exactly like the Luma Key effect instead of using the matte on the other track; in fact, I was able to create the exact same look just with Luma Key. And with Luma Key I have controls for Threshold and Cutoff, so I was able to adjust them until I got something that I sorta like. It's good enough. I think it's time to simply put the original problem in the "unsolved mysteries" category and go on. Hopefully TMK will work the next time I need it. Thanks, everyone!