Question / Help Chroma Key Worked Great-- Now, not so much. [SOLVED-- Sort Of]

[K. David Marple]

Howdy,

My chroma key was working great for the past week up until today when I was preparing to go live for the first time. After a windows update & Nvidia update my Logitech c920 decided it didn't want to be seen in OBS anymore (I'm guessing these were the problem makers).

Anyway, after installing some drivers here & there (again) as well as some software (again), I got ready to go, however now my Chroma Key halos my hair.

I shoot at night, so there is no light spilling in from the windows.

I double click the Color box in OBS & start be selecting the 3rd Green down (00 FF 00).

Next I start cranking up my Similarity until I most of the background is gone, which is around 780 to 840 depending on the lighting I'm trying to use & where I put them in my trial & errors...mostly errors. In a lot of videos & tutorials I see people with settings around 100, but I have also seen one close to 900.

Then the blend to about 44 & Spill to 1.

I've tried moving the Similarity & Blend up together 25 points at a time as was suggested in one video, but violet started to appear around my hair, so I backed the Blend off.

This is a picture of my Green Screen (the real stuff) as it is lit & I've seen MUCH worse setups with huge wrinkles & folds as well as people using sheets of green paper with amazing results-- yet I can't seem to get it nailed down.

Link to Full Size Picture: http://snag.gy/hNwLe.jpg

I have 2 soft boxes one on either side lighting the screen. I've moved them away from the green screen (basically, parallel with me), towards it (behind me), pointed the lights from up high down to my head level & had them at head level.

I've moved my entire setup further away from the screen & closer to it-- about 3' to 5' away from the screen...I could move further away, but I haven't because it involves moving a rather large drafting table & I had the chroma key working before today. If I were to move the drafting table, I could distance myself from the green screen by ~9 feet. And if I really had to, I could spin the entire set-up 90 degrees & probably make it ~11 feet. Not idea for the space, but...

Here is a 'working' picture with green spilling through my hair & a rippling effect around the black chair back. I have two lights in front of me at about 45%, but I've tried just one as well as a single lamp throwing diffuse light & then said lamp again with a single lamp off to the side. I have also tried a light behind me shooting forward.

Link to Full Size Picture: http://i.snag.gy/h1IBL.jpg where you can see the green spill.

I'm beginning to see why so many streamers wear hats or don't use chroma key.

Any help, would be much appreciated from here in the Pacific Northwest!

David

 

[Fantus_Longhorn]

I double click the Color box in OBS & start be selecting the 3rd Green down (00 FF 00).

Try doing this instead: Have Preview on when you go to the Webcam settings. Click the Select button next to Color, this will give you dropper which you can then click on the Green Screen in Preview. This will set the actual colour of your green-screen as the Chroma colour and will give you a much better starting point for your settings.

 

[K. David Marple]

Howdy,

Did as you said & it provided a better starting point than actually choosing the true Chroma Key color.

I also found this thread's suggestion here on the OBS forum about turning off most of the Auto functions of the c920 when working with Chroma Key helpful as well: https://obsproject.com/forum/threads/how-to-setup-chromakey.10085/

I moved the room around & placed about 9' between myself & the screen & played with the lighting...then I looked up (no, not at the ceiling-- the walls).

Sometimes we see something every day & it just blends in after awhile. The picture below is not my screen, but the color the ex-wife painted on all 4 walls & part of the wood floor in the room I'm using; plus there is a 4' x 8' mirror directly across from me I'm staring into when trying to set this up.

Please ignore the lighting here as this is just ambient light & not the lights I was working with...the next room over is green (but I turn the lights off in there).

So, I'm getting green light bounced all over the room & then on to me is my guess & the reason I'm having such a hard time.

I'll either paint the room or hang black curtains...think I'll paint & take the mirror down.


Thanks,

David

 

[bossjedizohan]

The issue is your Webcam's depth of field (area of sharp focus of the lens). Your webcam focuses on your face but can't also bring the back of your head and hair into sharp focus so you get the fringing. If you turn the spill reduction up it adds magenta to the alpha mask the other two option make and that cancels out the green fringe when you find the right value. Too much spill reduction and you'll get magenta fringing, too little and you get green fringing.

The best solution would be to put more distance between you and the webcam. It seems like you're quite close to the camera and if you back up, you'll have more room for your arms and head AND get more of yourself in sharp focus.

Also, make sure you have RightLight tuned off in the webcam software as that reduces the FPS of the webcam and leave all auto options turned off as well.

 

[bossjedizohan]

I should add that your initial screenshot with your lighting setup looks like a fantastic example of greenscreen setup and aside from being too close to your webcam and not using spill reduction, you seem to be doing everything right.

 

[K. David Marple]

Howdy,

Thanks for the information I really apprecaite it. I became frustrated after moving the screen ~9' behind me & moving the camera to a tri-pod a few feet in front of the desk. As well as everything else mentioned above.

I took the green screen down after the 2nd day of trying to get it all to come together-- frustrating when I see others with fantastic results & I have a green glow or magenta depending on how far I push the spill reduction.

I didn't put the lights away, so I'll pull it all out again when I have my weekend.

As far as the depth of field I'll give it the old college try again, but as the camera is less than a week or two old, I may take it back & move to a low end SLR/camcorder to improve on depth of field as I understand they are better for that & my Cannon D90 won't stream video without putting an overlay of information I don't want up on screen.

I measured the distance from my camera to me at ~6, but started with it hooked over the top of my laptop.

Once I noticed the color of the walls being so close to a blue/green I hung my head & packed it in...ended up playing Don't Starve.


Thanks

David

 

[bossjedizohan]

I think you're being overly hard on yourself to be honest. Your original images look very nice and aside from the depth of field, you're doing everything right. Don't waste your money on a video camera. The C920 is fine for what you're trying to do.