Chaos Corona Forum
Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: rozpustelnik on 2019-01-07, 13:40:23
-
Hi!
Any ideas how to achieve a hot air effect, like engine exhaust?
(https://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Swiss_F-5E_at_Fairford.JPG/220px-Swiss_F-5E_at_Fairford.JPG)
Preferably animatable.
-
A material with nothing but refraction on it (just like in the real world, where it's air at different temperatures causing refraction, but has no diffuse and reflection of course).
You could use static geometry with noise in the Refraction IOR. You could apply a noise deformer to some geometry. In both cases you could animate the noise. Or you could do a combination of both.
-
You could also use a Distance map to vary the strength of the noise, or the amount of the IOR, or both :) Since the effect varies in strength the further it is from the engine.
-
Thanks! I will give it a go and see what happen :)
-
You are welcome! Let us know how you get on (and share any renders and results, if you can!)
-
Just a quick test:
(https://i.imgur.com/6pQllXm.jpg)
Plane + black/white vertex paint in opacity slot + geometry noise. Strongly view dependent solution.
Also - noise solving time is rather long.
-
I would try with modelling some simple object (in case of trail behind a plane - maybe something like a plane stretching like a path), and apply a material to it with varying refraction IOR. I don't think using opacity makes sense, maybe just to soften the edges.
Another option is modelling some kind of "gas cloud" (possibly with particles) and assigning a refractive material to that.
Last resort is making a mask and adding this effect in post. ;)
-
I did various attempts at this in the past since my job involves doing exactly this. So far, I have resorted to do this in 2D post most of the time. Doing this in 3d with mapped faces may work (and look good), but you need to make sure they are facing the camera more or less, als you can run into many issues if the scene/camera is not static. It's pretty limited.
Doing this with anything other than a planar geometry (such as a sphere) will not be satisfactory. I've requested a ray travel distance map long ago for exactly this reason (among others). With a map like this you would be able to change the IOR depending on ray travel distance inside a geometry/volume. For example, using a sphere, you would specify the IOR to be 1.0 at the outside of the mesh and change it to 1.05 for example after 50cm, adding a slight noise somewhere in that map would then give you the heat haze effect. That way, the transition would be soft and any volumetric geometry would look fine without any tricks. However, this would probably involve ray marching calculations which would then slow down rendering a lot. In other cases, a map like this could be used to change a volume's color (or SSS color) based on a ray's depth within a geometry.
IIRC, PhoenixFD has an option to do this when rendering with Vray, I guess it's done in a similar way.
-
I've usually done this in post as well, gives you much more control. I used a particle system to first create something that roughly looked like smoke, then used that as a source map to distort the image in comp (displacement map effect in After Effects, but any comp software can do this)