View Full Version : Matte+Video problem

03 March 2007, 01:53 PM

I am new to Fusion so bear with me. ;)

I want to replace sky of the video with a matte painting. I succesfuly tracked the video, keyed the sky (with UltraKeyer, MatteControl and animated mask), but when i want to layer it properly, it won't do it. (

You can see two flows, one with the video (lower), one with the matte (upper). So far, so good and when i add them together with the Tracker node it adjusts the screen to the matte and then animates the video (not matte as i would want to) according to Trackers line. But the order of layers is correct - foreground is on the foreground and background is on the background. (

Ok, i thought, maybe just make it BG over FG, but then again it is animated correctly and the matte is tracked as it should, but now layers are wrong. FG is on the background, but BG is on the foreground. I circled the area where you can see the layer overlaying incorrectly. (

I then tried to use the first situation (FG over BG) and just crop it. But then again, the video layer is moving and croping it just doesn't work.

I am sure there is some super-easy way to correct it so please help me with this one. :shrug:

03 March 2007, 02:30 AM
In this case you'll have to do the composite outside of the tracker node. Here's an easy solution based on your existing flow:

1) Swap inputs on the tracker so your video is connected to the background input.

2) Set the tracker to FG only (now your matte should animate to match the video).

3) Add a merge after the tracker with the matte connected to the background and the video connected to the foreground.

That should do the trick ;)

03 March 2007, 12:05 AM
Hey, thank you so much for your response EricD. :)

But i still can't get it to work.
I think i got first two points correctly (please check, maybe i did something wrong), but the third one was a bit difficult. (

I added the Merge node after the tracker, but it didn't leave any inputs left for matte and video. So could you paint over how the flow should be or talk a bit more about that last step? That would be just super awesome. :)

03 March 2007, 12:10 AM
Sorry for doublepost. Some glitch with the forum.

03 March 2007, 01:56 AM
You don't need the two extra loaders. The tracker connected to the merge is correct. Disconnect from the merge foreground input and delete it. You can also delete the extra matte loader (concept##). Now simply branch off the MatteControl and connect it to the merge foreground.

I should point out that there are several other ways to achieve the same result, but based on your flow, this was easiest to explain.

03 March 2007, 09:40 AM
Thank you again, really apreciate your time an patience. :buttrock: But i still can't get it to work so i will just upload the file. There are some particle stuff that i did while having this problem, but that is not too important right now. ;)

Maybe you could point to some good examples on how to do the same thing only in different flow? Or some basic rules for this kind of situations.

And sorry for bothering you. :)

03 March 2007, 03:06 PM
Here's four possible solutions. To open the files, change the extension to .comp

If you haven't already, check out the Fusion courseware (

Good luck ;)

03 March 2007, 04:42 PM
Hey, thank you so much. :thumbsup:

I actually managed to get it to work after i posted that file (almost law of Merfy :)), but these comp flows will come in handy for sure.
Here is how i did it: (

At the end i have put Crop node so it is in the correct size.
And yeah thanks for the tip for the courseware, i actually have seen it, but nonetheless thanks. :)

03 March 2007, 07:44 AM you already noticed this, especially when tracking - if the size(resolution) of FG is different from size of the BG, then FG unstabilizing will not work as you need.
You already have solved your problem, but I think you want to know where the problem were.
When you have path/s from BG, and you need to connect them to FG/to unstabilize it to follow BG/, in order to work properly, size of the FG must be the same as the BG.
Of course, you can do it and with different sizes, but will be much harder/in some cases,even impossible/
Good luck with compositing :)

03 March 2007, 03:47 PM

You are right that i experienced that when tracking and i still can't get it right.
So your input is very important for me. ;)

But how then i use the matte painting if it is the same size as the video source? When the camera will move to sides or up and down there will be places where there is ''nothing'', just a white area.

Thanks :)

03 March 2007, 04:10 PM
Maybe I have to be clear about something - you don't need size to be the same in loaders, you need to be the same when you connect tracker to it.
I this case - before tracker you put resizer with size of the BG and movment will be fine.
For the other question - in most cases, a transform before tracker, with size set to big enough to cover these "blank places"(go to frame when you saw "blanks spaces" previously to be sure) - you need to check where is the most left,right,up and down position of the path (you can see where is this,right? ;) ), and most important - you have to UNCheck "flatten transform" of the transform, if is checked.
You may try to experiment a little to see which size is optimal.
If you need more detailed explanation, I will be here to write it :)

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