Heat haze effect

RBartlett wrote on 8/5/2007, 11:41 AM

I've not done this myself - I'd imagine the control engine would be the bump-map. However that still leaves you looking for the influence source. Ideally that would be a heat haze with a background you could key out. Assuming it is summer where you are and that you have a road (ie tarmacadam) at a suitable elevation for the background.

A heat has is has a polarisation about it that is probably difficult to simulate by recording moving water or steam against a background. An artificial volumetric light generator would seem the only way to pull this off (other than variations in the aforementioned ideas).

The closest natural source of a heat haze "Vegas bump-map" would be that of a saucepan of water or oil just as it starts to conduct disturbances that you can see as temperature gradients form. Maybe, with your lens not getting steamed up, you could bring these in to Vegas and apply them to your footage? Perhaps using a gradient to reduce the effect at higher altitudes in the source's 'field of view'.

Google for 'heat shimmer' 'mirage' or 'volumetric refraction' - there are a few ideas and plenty of paid-for options, though I didn't stumble across one for use directly in Vegas. (e.g. Tinderbox Heat Haze).

GregFlowers wrote on 8/5/2007, 1:10 PM

I'm not sure how to do it in Vegas. I know it can easily be done with ParticleIllusion, which is a fun and useful program.

TheHappyFriar wrote on 8/5/2007, 1:36 PM

This could be used in vegas.

most games do it by not only making things a little wavy but by also sheering the image. looks pretty good!

UKAndrewC wrote on 8/5/2007, 3:51 PM

Heat Haze in Vegas:

http://www.aimcosoftware.co.uk/video/heat_haze.mp4

http://www.aimcosoftware.co.uk/video/heat_haze.veg

Lots of parameters to play with and could be improved but the basic idea is noise, blurred and masked to the area where haze is wanted.

Andrew

Jay Gladwell wrote on 8/5/2007, 5:12 PM

Andrew, although that is a noble effort, it doesn't look like heat waves rising from a hot surface. You said it yourself, it looks like "noise."

I believe RB had the right idea, with the bump map. Just how to apply I can't say, but one has to take into account what is actually happening in order to create it visually.

UKAndrewC wrote on 8/5/2007, 5:23 PM

It is a bump map, and as I said not a completed effect just the idea.

If you don't know how to do something don't be so cheeky as to knock the efforts of others.

Andrew

farss wrote on 8/5/2007, 5:45 PM

Andrew,
with all due respect for your efforts, if it doesn't look right, it doesn't look right, no matter how good your intentions. I've ditched hours of work on FXs simply because I couldn't get them to look convincing.

Anyways that aside, there was a sample project of fire way back in the V4 days that included adding heat wave distortion to the background plate. Only a matter of removing the flames and maybe moding the noise generator and updating it to V7 to get this FX working. It'd still not be 100% accurate but I've used it projected onto huge screens as a backdrop for catwalk models and everyone was pretty impressed.

I'd be pretty certain the ,Veg is still sitting on the very server....somewhere.

Bob.

farss wrote on 8/5/2007, 6:06 PM

OK,
just found the ancient fire.veg from way back in 2003.

I don't have all the assets (like the background plate) but that's a no brainer to replace, in fact if you were trying to use this to add a heat haze to an existing shot you'd have to that anyway. The file is only 33K, opens OK in V7 etc. If anyone would like a copy email me and I'll email it back.

For all I know a copy is probably kicking around somewhere public but if you can't find it, like I said, email me.

Bob.

UKAndrewC wrote on 8/5/2007, 6:11 PM

Bob and Jay

...and could be improved ....

Previous posts suggested a bump map but no method. I have provided a method for using a bump map and how to mask it. It's a progression, not a solution.

and your effort can be viewed where?

Andrew

Serena wrote on 8/5/2007, 6:12 PM

http://www.vasst.com/resource.aspx?id=3260550a-9d17-447e-b9b3-242ff279c5cfheat effect[/link] isn't a bad start and is guidance on procedure. The best example of the real thing that I know is in Lawrence of Arabia. Lacking that the warm tarmac and long lens is the way to get a look at the real effect -- that is usually better than attempting to create an effect purely from vague impression.

EDIT: Actually I thought Andrew's effort not a bad foundation. It is horizon haze and needs to be slowed down and it needs a background plate to show optical distortions. I think we see a problem in Andrew's specific solution because it is confined to a narrow band and appears to show convection currents rather than their optical effects on the background. As I said above, you do need to state specific requirements before you can design an effect.

farss wrote on 8/5/2007, 6:20 PM

OK, everyone, let's chill out.

The project file "fire.veg" can be found on the VASST site, just do a search for Fire. In the search results look for "Tree on Fire", written by Kim from SoFo, January 21, 2003.

Yeah sure I could do the work of modifying it and post something somewhere but that's hardly fair as I'd be knocking off someone else work and spending time re-inventing the wheel.

The trick by the way is to use the correct 3D compositing mode, so that the map spatially distorts the image, take a careful look at the fire.veg and you'll get the idea of how to use displacement maps to reflect images off water, make flags wave etc.

Bob.

Serena wrote on 8/5/2007, 6:31 PM

That's very good. http://www.vasst.com/search.aspx?text=tree+on+firetree on fire[/link]

EDIT: The desired heat haze effect is in the bottom third of the frame.

farss wrote on 8/5/2007, 7:09 PM

OK,
I'll have to admit that Fire.veg is fairly complex and one could easily get lost trying to mung it into service so here:
http://www.madison.thewikies.com/viewtopic.php?f=33&t=38

Is a modified version complete witth sample image.
Replace the sample image with your video and adjust the noise generator to make it look more like heat haze and less like a raging bushfire. You can also adjust the gradient mask to control which part of the image is affected by the haze.

Bob.

douglas_clark wrote on 8/6/2007, 2:11 AM

You might look at the NewBlue Wiggle FX (in the Motion Effects collection). A bit of vertical wiggle with slow Drift might be shimmer-like...when used in combination with some haze effect.

Actually, I guess the Sony Wave FX does the same thing as the Wiggle FX. Vertical waves, slight amplitude, and vary the phase slowly.

24Peter wrote on 8/6/2007, 9:22 AM

Thanks all.

Bob - looks like the Heat.veg might do it.