[Jery Ervin]

For each newly appearing ‘ring,’ use an event on a track above any existing visible events (on tracks below) with an cookie-cutter effect applied to the event. Animate the ‘size’ parameter of the cookie-cutter event, starting at or near zero & growing over time.

I think this will do what you want.

[Jery Ervin]

Hi, Dan,
A simple fix is to use an Event Pan/Crop Mask on the event that is being multiplied. To do that, select the event to be multiplied, go to its Event Pan/Crop panel & look at the timeline in the panel. There should be a checkbox to the left of the work “Mask” under “Position.”

Check that box & then use the tools that appear on the left margin of the Event Pan/Crop panel to click on the frame to create a rectangle around the part of the frame that you want to appear in your composited frame. The tools are similar in function to pen tools in Photoshop.

The key to understanding the behavior that you are seeing is the subject of transparency of pixels/parts of images.

In Photoshop, the multiplied pixels that are over the parts of the image that appear from the lower layers are transparent (or, could be pure white). Transparent (or pure white) pixels, when multiplied, have no effect on the layers below.

In Vegas, “empty” pixels are not transparent, they are actually black. As in Photoshop, black pixels, when multiplied, completely block the pixels in tracks (analogous to Photoshop’s layers) below the multiply track. The result is as you see in your tests.

Regarding transparency in video images, certain video formats support the idea of an alpha channel/layer, which could be used to cause the behavior you desire. The Event Pan/Crop Mask technique is simple and effective and, I think, will do what you want.