If you are talking about the "depth" slider or arrows adjustment, it will change the size of the clip in 3d space.

Set a "0" the picture disappears into the distance. Set at 24 it is full size 720x480.

You can adjust the size in the "perspective" window for the same thing.

It works fine for me.

Thanks Nickle but i still dont understand this feature.
Try this: uncheck “lock aspect ration” and you can have a full size (720*480) with a Depth to 0.
Make some rotation with some “depth” adjustement. The changes you can see in the perspective window have no result in the preview window.

This as a tricky excercise in higher mathematics.

If you lock the aspect ratio it will maintain the dimensions relative to each other.

The depth of the event (thickness) is like the thickness of a photograph......almost nothing.

But if you unlock that, you can increase the thickness but it doesn't show on the preview because there is no information to show.

I think if it was a cube, then the depth would increase in the preview window because there would be something with information to show you.

Make sense?

I think the gurus are hanging me out to dry on this one.

>>>The depth of the event (thickness) is like the thickness of a photograph......almost nothing.

Finally, what is the utility of this feature ?

3D is an optical illusion.

If you have a spinning cube, it looks like it has a top and bottom and 4 sides.

But it really doesn't have any "real" depth, it only looks like it. It is like a still picture which has only height and width.

It is perspective, light and shadows, relative sizes of objects and dimensions aerial perspective (haziness and blurriness of distant objects) which gives the illusion of depth or 3d.

The function of locking the aspect ratio allows for adjustment without distortion which has merit. That is why it is available.

Unlocking it allows you to distort the ratio of height to width because of the information contained on the face of it that you can see.

The thickness has no information therefore even though it is adjustable, there is nothing to adjust. Therefore unlocking has no use for thickness of information that doesn't exist.

Adjusting the volume of a tree that falls in the forest with no one there to hear it is also a waste of time.

Keep in mind that just because I can't find a use for it doesn't mean that there isn't one. Programs like Boris allow for creating a cube and adjusting "depth" but I don't know how to do it in Vegas. But once it is created in Boris, it is rendered as a 2D file which is not adjustable in Vegas except for height and width and no depth.

So unless someone much more knowledgable about this than me jumps in and bails me out, I have no more information.

Thanks Nickle,
With your explanations I finally understood the “Depth” utility.
With two 3D tracks (nested track) we can modify perspective with the depth slider.
See this project for more details:
http://sony.vegas.1.free.fr/depth.veg
Thx again
Gilles (from France)