Help me to improve my key of this cat clip

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Old 05 May 2013   #1
Help me to improve my key of this cat clip

Hi. I'm using nuke 7.0v6.
As I'm a total noob since yesterday I'd like to know how I can improve the key of this sequence that I found on the net.
There's some spill as you can see which I'd like to remove and also in the shadows at the feet. Overall it's a bit happening with the pixels and I guess since it's not in HD I have to live with some of the artifacts. I'm planning on render out some cameramove taking you to a box that opens to reveal the cat so I can hide parts of the cat as I need. That's the idea anyway.

What do you think of the camera track? I'm about to learn how to export it to maya. Seems to need to use a script, but I've understood I need to connect a camera to the track aswell. Anyone care to elaborate on that?

I've followed along in some youtube tutorials, but also planning on doing one of those massive projects like Eat3D has, but it would be cool in the meantime to understand the program and try out some easier tasks before jumping in full on.

Here is the images and my nuke file. Hopefully it should work for you?

Thanks for looking!
 
Old 05 May 2013   #2
I think it's the noise that will make it very hard to get a good key. As a general rule you should denoise your plate before keying it. About the spill, erode your key inwards and use that as a mask for a hue correct where you suppress the spill. Maybe use some simple blurred rotos for extra spill control. I'll attach a script showing some basic examples using your plate.

Also, the most common technique is to use several keyers for different parts of the plate and combine them into one.

Google for nuke camera tracker, that should give you info on 3d-tracking. But both the camera tracker and denoise nodes are only nukeX I'm afraid.


But I think the main thing is: if you want to learn keying, use quality plates.
Attached Files
File Type: zip catScript.zip (38.6 KB, 7 views)

Last edited by Ekenryd : 05 May 2013 at 12:54 PM.
 
Old 05 May 2013   #3
I thought I answered this a couple of days ago =/
Seems it never registered...Thanks alot!

I will look into all the suggestions you've given and the most obvious one to get a better footage. However, I can't afford any atm so I'm relying on free ones.
If you have any great places you know of, please share =)


Would you mind elaborate on the following sentence:
"Also, the most common technique is to use several keyers for different parts of the plate and combine them into one."

How would I go about this?

I have been looking into camera tracking aswell, but I haven't found any info on how manually tracking a shot and use that to connect to a 3D camera =/

I generelley prefer that method which I was familiar with in Maya Live long ago, but nowadays seems that's not being used. Should I just rely on the automatic camera tracker?


PS. How do I use the script you attached?

Thank you very much
 
Old 05 May 2013   #4
Quote:
Originally Posted by Geuse
Would you mind elaborate on the following sentence:
"Also, the most common technique is to use several keyers for different parts of the plate and combine them into one."

How would I go about this?


I just want to say that I'm still an amateur when it comes to keying but I'm lucky to be surronded by great compers here at work, so when I've done keys I learned a lot about keying theory thanks to them.

Basically, it's usually pretty hard to get one key to cover everything. In the script I posted I for example keyed the cats shadow with a seperate key. Not that it might be necessary in the cat case, but more just to show you. Here I just merged it with your main key.

Then if you look at the green screen it self it looks a lot different colorwise on the floor compared to the wall. In this case with the very low quality footage I belive you did it right by pulling a pretty hard key, because it would probably be to much flicker around the cat if you try getting more detail, but if you were to do the same with HQ footage, you'd probably make a key that looks nice for the wall green screen, then one for the floor, and the draw a quick roto for the wall, blur it a bit, and the use the keymix node or similar to merge the two keys. And maybe one for the whiskars, etc.

But there are many many other solutions, and these are just the most general ones. A good start I guess, if you can't get the key you want with just one key

Quote:
Originally Posted by Geuse
I have been looking into camera tracking aswell, but I haven't found any info on how manually tracking a shot and use that to connect to a 3D camera =/

I generelley prefer that method which I was familiar with in Maya Live long ago, but nowadays seems that's not being used. Should I just rely on the automatic camera tracker?


In your script you used the regular 2d tracker node. To get a 3d track you have to(at least to my knowledge) use the camera tracker node, which is available in nukeX. If you use that node, you can generate a scene node and a camera node from the track, and then attach a scanline render to those, and you got yourself a tracked scene inside nuke. Or you can just export them as fbx into maya.


And you use the script by just opening it with nuke
 
Old 05 May 2013   #5
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