Cut away section visual effects

RockeyNumber1 wrote on 5/12/2006, 8:56 PM
when i click on a visual effect and it gives me several options, i see one that says cut away section. i assume that means i can trace around the portion of the screen that i want to be in the effect. however when i click on it, i cant seem to figure out how to exactly do that. will anyone please tell me how to do that?

Comments

Tim L wrote on 5/13/2006, 9:06 AM
I assume you are talking about the "Cookie Cutter" effect?

This effect is very useful, but frustratingly limited in VMS. It will let you select a shape from a predefined list (circle, oval, rectangle, square, etc.), and basically use that shape to cut out an area of one video and overlay it on top of another.

Start with two video events (or still photos, or generated media, etc.) Place one on a track above the other, and place your cursor somewhere in the middle of the event so you can see it (your top event) in your preview window.

Now apply the Cookie Cutter effect to the video on the upper track. When the Video Event FX window appears, select a shape from the list. For this example, we'll assume a Circle is selected.

Enable the Border -- even if just temporarily -- by assigning it a value > 0.0 (0.01 will do). You might make it red to help see it. If you don't see a shape outline in your preview window, start reducing the Size value until you do. (Initially, the shape might be so big that its outside the edges of your video.)

At this point, you should see that everything inside your shape is from your top video track, and everything outside your shape is from the bottom video track. That is, the circle contains video from your top track, and everything outside your circle is what shows through from the bottom track. The drop-down box that says "cut away all but section" lets you change this. Select the other option -- "cut away section" -- and now the situation is reversed. You see all of your top track video, except the circle shape looks like a hole that lets you see through to your bottom track.

You can use the little blue button (in the white area below the color selectors) to move the position of the circle, and use the size adjustment to control its size. You can change your shape selection with the drop-down box, but you are limited to those shapes only. If you select "rectangle", for example, you are stuck with the predefined rectangle shape, which I think is the same shape as your video format (regular or widescreen). You cannot control the shape of the rectangle -- make it taller or skinnier, etc.

Once you've got things set, you can get rid of the border, if you wish, by setting it back to 0.00. You can use the "Feather" control to soften the edges of the shape, rather than having a hard edge.

Note that all of this is keyframeable, so you could have a circle shape that moves across your video, left to right, or you could have a very tiny circle to start with that opens up wider, then closes down again -- kind of like the thing at the end of the old cartoons credits. ("Th-th-th-that's all, folks"...)

Also note that all effects have a "?" button in the upper right corner that brings up a window describing all the settings.

By the way, I think that big brother Vegas (the full, pro version) has a much more extensive masking capability, allowing you to draw freehand masks of any shape to do this sort of thing, but we are limited to just the defined shapes (unless somebody knows a way around this? or a way to add your own mask shapes?)

I hope this helps.

Tim L
Tim L wrote on 5/13/2006, 9:56 AM
On second thought, there *is* a way to do masking with custom shapes, but it is a little tedious (I haven't tried it yet myself).

With VMS 6, we now have parent-child compositing, with just two modes: Alpha, and Multiply. Multiply works a little bit like a chromakey, except that anything full white will "keep" the child source image, and anything full black will make that part of the image transparent (so that lower tracks will show through).

For example, assume you had an outdoor scene, where the camera is on a tripod and is static for the entire shot, and you wanted to replace the sky with a "space" image (maybe a starry sky, or a big planet or something). You could manually create a mask in a paint program, so that everything in the foreground is white, and everything in the sky is black. Use this mask with parent-child compositing, set for "multiply" mode, and then you can basically create a "mask" any shape you want. You need a total of three video tracks to do this. Your hand-drawn mask on top, your foreground shot below it (as a child), and finally your background sky image below that.

To manually create a mask, export a frame of your video using the "floppy disk" icon in the preview window (set for Best(Full)). Import that .png or .jpg image into a paint program, and draw on top of it to match the cutout shapes you need. Use a paint "fill" function to fill the areas you want to keep with white, and fill the areas you want to be transparent (so your lower background shows through) with black. Save the mask and then bring it into VMS as the parent compositing track.

Again, I haven't tried this myself, but that's my understanding of how it works.

Tim L
RockeyNumber1 wrote on 5/13/2006, 1:09 PM
yeah, i knew about the predefined shapes, but was wondering about drawing my own, which i guess you cant do. well alright. i guess that will have to do.