It may not be perfect, but I think this chain of FX works very well for chroma key within Vegas. I only tried it on the one clip I have and want to do some more testing, but I think it's much better than using Sony's Chroma Key FX alone.
As you proceed, add these FX to the Track FX rather than the Event FX. Later, after all effects are added, the process calls for you to copy the event; if the FX are on the original event, you will copy those FX with the Event and cause confusion.
Step 1: Drag your source clip onto the Vegas timeline.
Step 2: Add the Color Curves FX and set to Reset to None.
Step 3: Add the Color Corrector (Secondary) FX and set to Saturate Greens preset. You will immediately notice the green screen becomes heavily saturated and brighter.
Step 4: Add the Chroma Keyer FX and set to Pure Green Screen.
Step 5: Rather than use the dropper, adjust each color channel manually. Make small adjustments to find the best middle ground for each color, R, G, and B. Basically, grab the small white arrow on the Red channel slider and move it to the right. You will notice the background start to get darker. There will be a point when the background begins to get lighter again. Try to find the spot just before it begins to lighten. This is your sweet spot for the Red Channel. Repeat this for the Green and Blue channels.
Step 6: Next, adjust the thresholds and blur amount. Begin by raising the low threshold and lowering the high threshold. You want to find the point where the green screen completely disappears without removing the edges of your subjects. Remember that there are adjustments left to go through so it may not be perfect yet. Once you find the best place for the thresholds, raise the blur amount to allow a smoother look to the edges of your subjects. But not too much.
Step 7: Most DV sources inherently have a green tint to them. CCD's seem to be more sensitive to the color green. This is why most DV Chroma Keying is done in green and why most film is done in Blue. Now, since we boosted all of the green in step 3, it makes our subjects a little too green as well. By adjusting our color curves we can clean up our Chroma Key a little more. It's best to only adjust the lows of the image, since we want to keep the highlights as bright as possible to pick up the green screen.
Spend some time now fine tuning using the Color Curves FX. Click on the Color Curves FX in your FX chain, click the Channel drop down list, and choose the Green channel. Double click in the lower quarter of the line to create a tangent then slowly pull that tangent point to the right. Watch your image closely as you move it around. You probably wonít have to move it much. You want to pull a little of the green out of the blacks and subjects but you don't want to throw the color balance off completely.
Step 8: Go back to your Chroma Keyer FX and make small adjustments to the thresholds, the blur amount, and the color adjustments. If finer tuning is still needed, you can also make small adjustments to your other FX in the chain as well.
Step 9: Change the Chroma Keyer FX to Show Mask Only. Notice the pixellation at the edges.
Step 10: Add a Gaussian Blur FX. Reset to None, then adjust upwards by 0.100 increments (mouse wheel scroll) or by 0.001 increments (Ctrl and mouse wheel scroll) to just remove the pixellation.
Step 11: Add Black Restore FX. Donít worry about adjusting yet, leave at the default.
Step 12: Add another Gaussian Blur FX. Set it to None.
Step 12.5: Add the Mask Generator FX.
Step 13: Add a video track below this track and copy the event from this modified track to the new one. Be sure it is below the modified track. Make the new track a child of the first track and set the modified trackís Compositing Mode to Multiply (Mask).
Step 14: Go back in to the top track FX chain and modify the Black Restore. Adjust upwards until the remaining green is removed from the edges, but be sure not to encroach the edges of your objects or subject.
Step 15: Adjust the next FX, Quick Blur, upwards until the sharp crispness at the edges created by the Black Restore is softened a bit. This may be way up at 1.000, or you may have to add additional Quick Blur FX to soften to your liking.
Of course, this will work much better if you shoot in Progressive mode and light properly. Pull the subject away from the green by several yards and light the green screen with very even lighting. Use your camera as a light meter on the green screen by changing the exposure so that when the zebras appear, they appear across the entire field at once. Light the subject well, including a kicker/hair light and proper exposure of their face.