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View Full Version : Help with keying (Nuke, Blender)


DanielWray
04-27-2012, 12:21 PM
Hello,

I'm keying an object that is reflecting a lot of green screen, I've managed to get a satisfactory key from most of the robot, but there are key areas that seem to be reflecting too much green, destroying the overall key.

Some of the areas that are ruining the key are; Robots right arm, chest area on left side.

I 'could' at a push re-shoot the footage, but I'll still end up coming away with footage that has the subject reflecting green.

I've uploaded a few plates, it'd be great to have some hints, opinions etcetera on what may be the best approach to it.

http://s17.postimage.org/ok32gjf57/Grab_002.jpg (http://postimage.org/image/ok32gjf57/)

http://s8.postimage.org/gqjbtw7sx/Grab_001.jpg (http://postimage.org/image/gqjbtw7sx/)

TheOnlyAaron
04-28-2012, 06:42 AM
I would recommend re-shooting the footage, and if you do not see the robot in contact with the ground, have it on some ground that is not green. Also light the screen and the robot as seperatly as possible and have as much distance between them as possible to get the cleanest and best key.

If you dont re-shoot it, I think you may need to do some roto during those motion blurred areas, and then heavily treat the footage afterwords.

DanielWray
04-28-2012, 12:35 PM
I think you may be right Aaron, after a few attempts at keying some of the issues still prevail quite noticeably.

I had a green screen under the robot when shoot, which is responsible for all of the green spill / reflections - I was in a rush so didn't think through the implications of this! :blush:

Kai01W
04-29-2012, 08:26 PM
Hello,

I'm keying an object that is reflecting a lot of green screen, I've managed to get a satisfactory key from most of the robot, but there are key areas that seem to be reflecting too much green, destroying the overall key.

Some of the areas that are ruining the key are; Robots right arm, chest area on left side.

When you say "destroying the overall key", do you mean you are trying to pull just one key for everything?
If you can get a decent seperate key for just that area you should just combine them with a roto. Really. It almost never happens that I use just one key to generate the final matte. Even if I could find settings which would pull a key for everything it would usually be too comprimised with regards to edge detail/softness.
As long as you can pull a decent enough key of that problematic area (maybe with the help of rotoing) its best to just combine several keys.

-k

DanielWray
04-29-2012, 09:33 PM
Bad wording on my part, I was making use of a few keyers to get the overall key.

The main issue with the keying is actually what appear to be blocks of the greenscreen that I can only assume are coming from the heavy compression of the video - I'm also very new to Nuke so perhaps wasn't combining, and using the keyers in the most efficient ways either.

Of all the shots I got though it is primarily this one that is causing the most problems so I shall reshoot, and this time I shall setup more of a stage under the robot, and perhaps behind him if possible, to minimize the amount of green screen, and reflections.

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04-29-2012, 09:33 PM
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