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View Full Version : Q: RayMarcher?!?!?


cyroz2000
06-18-2003, 08:55 AM
I need a volumetric ground fog for a short, but it seems that I won't use raymarcher;
Does somebody use it?
And how?
For me the ground fog "ray marcher" is not usable for animation,
even if you set it to very low quality, render times are HUGE!
I believe it can make good results, for stills, if you're a little bit patient (but I'm not).
So wavers, please tell me if you use it, how do you set it so that render time is acceptable, or if not have you got a workaround to achieve the same effect (I also tried spray point->hypervoxels...
but the result wasn't very good!
Thx in advance, see you!

Tudor
06-18-2003, 09:17 AM
You can always place something like 10 layers of polygons on top of eachother with a little offset until you reach the height of the fog you need, then add a transparancy map..
Works ok in most cases.

cyroz2000
06-18-2003, 09:42 AM
Thanks for the trick, Tudor, have you got some examples?
Anyway, I'll try this this afternoon, thanks.

Mike RB
06-18-2003, 09:45 AM
do a search for coffee on flay. Apply that to a lage plane with noise low to the ground... Possibly a displacement texture to wobble it slowly... Tweak the falloff distances, add a noisy texture, animate that as well, it will render fast and you'll like the result.... (combine it with normal depth fog)...

Mike

SplineGod
06-18-2003, 09:50 AM
The stacking polys ground fog trick is how we used to do it in the old days. :)
I would recommend vibrating the stack up and down very quickly and turning on motion blur. If you use a fractal noise in the transparency channel make sure to turn on world coordinates.
Another method is to use HV sprites as a ground fog.
You can define where the fog goes by using Textures or a particle object in another layer. It can be made by copying the ground polys, subdividing a couple of times and then killing the polys.
HVs only need vertices.

SplineGod
06-18-2003, 10:29 AM
Heres a quickie example of using HV sprites to create ground fog.

SplineGod
06-18-2003, 10:42 AM
Again heres a quickie example with stacked polys, vibrating them and turning on motion blur. Im using fractal noise in the tranparency channel with world coords.

cyroz2000
06-18-2003, 11:07 AM
Thks Larry, the stacked polys method seems to be really good,
I will give it a try, the HV one show the grid of the subdivision of the poly too much, maybe it needs more points but it may extend render time.

SplineGod
06-18-2003, 11:43 AM
What I would do with the HVs is to up the subpatch just a little or copy/paste the geometry where I wanted the fog, subdivide it, freeze it and kill the polys then jitter the points a little.
Ive done good looking ground fog with HVs that animates well. I threw this together quickly as an example with not tweaks. :)

Tudor
06-18-2003, 11:54 AM
Darn it Larry! You beat me to it! ;)

Well, here is my example with the same technique:

Oh.. btw, you can even fake grass and plants with this technique.



Originally posted by cyroz2000
Thanks for the trick, Tudor, have you got some examples?
Anyway, I'll try this this afternoon, thanks.

Maxx
06-18-2003, 12:08 PM
Personally, I like this one - Happy Digital (http://www.happy-digital.com/freebies/groundfog.html). Renders much quicker than ray marcher, and looks better IMO.

cyroz2000
06-18-2003, 12:41 PM
Thanks for the link Maxx, will try it, do you know if there is a way to use procedural with HD ground fog?

Maxx
06-18-2003, 01:23 PM
Doesn't look like it, no. Should probably e-mail and ask for that as a feature request. The plug takes some playing with to get results, but the results it gives are goo, I think. And they are definately fast....

Kvaalen
06-18-2003, 04:22 PM
Tudor:

Your test looks great but I think it'll look better if you gave the planes a displacement map too.

Mike RB
06-18-2003, 05:40 PM
try the coffee plugin

http://koti.mbnet.fi/anttij77/Plugins/Sininenplaneetta_Plugins_Coffee.htm

Tudor
06-18-2003, 08:34 PM
Kvaalen:
Nothing to give displacement to. This is just 15 polygons stacked on top of eachother..
With a little more work you can tweak the texture to make it look a lot mor bumpy. This only took about 5 minutes to set up though.

Kvaalen
06-18-2003, 09:09 PM
Originally posted by Tudor
Kvaalen:
Nothing to give displacement to. This is just 15 polygons stacked on top of eachother..
With a little more work you can tweak the texture to make it look a lot mor bumpy. This only took about 5 minutes to set up though.

I understood how you did it from your earlier post but it's a little to visible that it's polygons stacked up since the top is to flat.

My idea was to give a displacment map from the deformation tab under the object properties (procedural or something). That way it won't have that perfect ending on the top.

Cool idea though. :thumbsup:

Tudor
06-19-2003, 09:53 AM
Well.. adding a displacement there still need more polys. otherwise just the corners will be displaced, as thats where the only points are.
It is better to create a better falloff from the bottom and up, so that the top layers are almost not visible.

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