Funny havent thought about Video Factory for a couple a years, but second tme this week reccomending the content cd of factory .It carries several very ,very good cloud fly throughs. Probably buy it on ebay for next to nothing.

Getting 3D results would be tough. However, you can get a first approximation using the Vegas Video Media Generator. Insert a Sony Noise Texture. Use Fractal - Turbulent. Use these settings as a starting point:

Number of layers: 3.5
Frequency X: 1.5, Y: 3.0
Offset X: 1.5, Y: 0.0
Progress: 0.0
Noise parameters Min 0.0, Max 1.0, Bias -0.30, Amplitude: 2.0, Grain 0.50

Color A R 119, G 172, B 255 A 255
Color B set all to 255

Similar to John's approach with a few added ideas -

I put Soft Clouds Noise Texture on four tracks, staggered so that one fades up as the previous fades down, except the bottom one which is there the whole time.
The top three I made the blue colour transparent.

Then used keyframed Pan crop to graduallyzoom in on each one.

Not a bad "fly through". Have a play ....

1- There might be a way to get real footage of it.

Pilots: Every few months, they have to take a flight to keep up their license. If you can schoomze them and tag along you might be able to get the footage you want. They may not want to be flying in clouds though.
Skydivers: If you want some skydiving footage, you can email me at gchanATuts.oise.utoronto.ca I may be able to send you some. You only see people falling though clouds though (but not through the cloud, because the footage doesn't work well in that case).

2- If you want to generate clouds, Combustion may be a good way to do it.

Thanks so much to everyone who responded to my question. I have a followup question for JohnMeyer and/or PeterWright.

I tried your suggestions, and came up with a reasonably realistic looking cloudscape. Much appreciated! But unless I did something wrong, I didn't actually see any movement until I applied some panning, cropping and zooming to the clouds.

For clarification, did I do this right? Would I also need to do pans and zooms on the individual cloud track(s) to achieve the look of fly thru movement that I'm after? Or did I leave something out of your instructions that would cause the illusion of 3-d movement?

Thanks!
Rick <><

That's pretty much the problem.
With Vegas you can composite and manipulate 2D planar surfaces. But that's all they are 2D objects and you want to move through them.
So you face two problems.
1) Being 2D you cannot realistically change the perspective of the objects.

Simple example. Take a photo of someone and drop it into Vegas. You can turn and twist the photo, this is not the same as having the object (person) move in front of you, if you rotate the person 90deg to camera you see their side, rotate the photo 90deg and you see nothing, just an infinitely thin edge.

2) With Vegas you can only move the 2D objects relative to the camera not move the camera through the objects.

If Vegas supported 3D objects (and it wouldn't be a NLE if it did!) you can sort of simulate having the camera move by moving the objects but it becomes a nightmare keeping track of what's going on, much easier to fix the objects in a 3D space and move through them.

All this is without considering things like lighting and depth cues.

I'll go further and suggest that even with expensive CGI software clouds are a difficult thing to create as they defract and reflect light in very complex ways, they're not just solid white blobs. Also as you fly through clouds very interesting things happen to the light, spend some money and take a flight in a glider with a video camera, apart from getting the footage you need you'll have one heck of a good time, should cost under $100.

Bob.

Yes, it's all a matter of illusion.

What I tried to do was create a few different layers of clouds, and use pan/crop differentially on each layer to make it look as if I was moving through each in turn.

To add to the illusion, each Generated Cloud event can be keyframed to be moving as you zoom through. A slight change in the "Progress" slider between beginning and end is enough to do this.

Also, the "clouds" can start with blur applied and become sharper as they get nearer.