photoreal rain?


(stephen2002) #1

Has anybody developed a method for doing photoreal rain that is not too hard on the number of verts in a scene. I have though of two methods, vector particles and indivdual animated drops that would then be dupliverted. I am running low on verts in the scene that I am working on, so I am looking for a low-poly solution of some sort.

I will start hacking away at the issue myself soon, but I just wanted to see if anybody has established a method. It must be resonably photoreal during animation and still.

Any ideas?


(valarking) #2

realtime or static?
if realtime:
good luck, hehehe…
if static:
why keep the polycount down? that’s what layers are for!


(stephen2002) #3

The rain is not for a game, but for an animation (not a still).

Layers don’t work like that. I still have to render all of them in the end! My vertex count is about 1.6 million right now. I don’t know the exact limit of Blender’s rendering system, but I think that is pretty darn close.(the v1.8 manual says 1024K, or 1,024,000 so that must be wrong) In fact, I had to decimate the trees in order to keep Blender from crashing on render.

I could composit, but I am going to try to steer clear of it. I had some strange results last time I tried it.

I was hopeing for ideas?


(theeth) #4

well, you could go cheap with an animated texture on multiple planes. Just make sure you change the offset on the different planes, so that the pattern is not too synchronized.

Particles might be good too, but instead of the render happy halos, you could use a dupliverted edge with a wire material.

Martin


(stephen2002) #5

hummm…the dupliverted edje effect dosn’t seem to look like rain. I can get quite a bit of rain in the background, but usually all I end up with are a few specks in the foreground. I can’t seem to get the rain to be dence enough. I have the particle count cranked up to the max and four rain emitters in the area. Maby I will make more emitters.

Any other ideas? Particles and edjes don’t really look like rain.


(Pablosbrain) #6

Put some emitters right above and in front of the camera. if the rain is going straight down you could also parent the emiters to the camera to make final camera placement easier once you get the look you want.


(stephen2002) #7

humm… now thats a good idea. I didn’t think of that, just put rain where you want it and nowhere else.

Thanks!


(Cessen) #8

I’ve gotten quite good results with vector particles. Of course, the rain isn’t any more photo-real than anything else rendered in Blender, but it looks quite believable.

BTW: if you do rain with particles, make sure to tweak the “add” setting in the particle material (I have found that an “add” setting close to or equal to zero usually works best, because then the “rain” isn’t emmiting light…).


(Ulli) #9

I gained very good results combining 2 different types of rain in one scene.

  1. The background-rain is simple: Just apply two textures (clouds) to your world-setting and animate them by parenting each of them to a spinning empty. One should be a bit slower than the other one. Make the scene “foggy” and you got exactly what rain looks like in the distance.

  2. For the foreground-rain place two or three particle systems right in front of the camera. Emitter should be a slim triangle thin end up and thick end down.

Besides this the most important point seems to be a proper motion blur value!!

[/img]


(stephen2002) #10

I think that I will stick with vector particles. Thanks for all of the tips!

It already takes about 5 minuts/frame (without the animated environment map) so I am not about to do motion blur if I want to see this project come to a close.

Cessen: Blender can make fairly photo-real results. Just take a look at some of my Intrigue posts in the “I made this” section. However, that is about as good as it gets in my opinion.


(Ulli) #11

Sorry to say, but without motion blur you definately WON’T gain realistic rain…


(stephen2002) #12

:frowning: :frowning: :frowning: :frowning:

Will have to do some experimentation. If so, this is will be the only segment in a 5 part pice that has MotionBlur. I think that it might look a little bit strange to have Motion Blur on only one part of the whole thing.

Plus, I would like to have the project finished by May 10. Lets see… 10 min/frame NO MBlur * 8 MBlur frames = 80 min/frame * 450 frames = 25 DAYS! :o PLUS I am not done with the 5th part, so that = more render time = too much!

Maby I can play with vector particles or something to achive the streaked effect. Or render the rain as a separate pass?


(valarking) #13

:frowning: :frowning: :frowning: :frowning:

Will have to do some experimentation. If so, this is will be the only segment in a 5 part pice that has MotionBlur. I think that it might look a little bit strange to have Motion Blur on only one part of the whole thing.

Plus, I would like to have the project finished by May 10. Lets see… 10 min/frame NO MBlur * 8 MBlur frames = 80 min/frame * 450 frames = 25 DAYS! :o PLUS I am not done with the 5th part, so that = more render time = too much!

Maby I can play with vector particles or something to achive the streaked effect. Or render the rain as a separate pass?[/quote]

well, maybe try lowering OSA to 5, or lowering the resolution, or any one of these things to lower the time. unfortuneatly, vector particles look like total, utter, complete, CRAP without mblur.


(stephen2002) #14

I have blended a few different methods together and made some fairly convincing rain. Here is a link to a rough render of the results:

http://sflare.50megs.com/feedback/feedback20/feedback20B.html


(theeth) #15

When rendering with motion blur, you can disable OSA enterely, since the final blur will have the same effect on jaggies. That should cut a lot of render time from your 25 days.

Martin


(S68) #16

[quote=“theeth”]When rendering with motion blur, you can disable OSA enterely, since the final blur will have the same effect on jaggies. That should cut a lot of render time from your 25 days.
/quote]

This is true only if the camera is moving, if camera is still and a single object in the scene is moving then oly that object will have AA, wile the rest of the scene will be jaggied… At least I found that keeping OSA at least to 5 gives much better results

Stefano


(LethalSideP) #17

Can I suggest that you create your particles in a seperate Blenderfile using particles, motionblur, etc but you IMPORT YOUR CAMERA FROM THE ORIGINAL SCENE. This way all the angles will be OK and everything. Then just add it in post process, or stick a plane in front of the camera and put it there (with alpha mapping etc, of course). The nice thing about this method is that your rain can now have (NEARLY) as many verts as you want, regardless of the original Blend file.

Just my $0.02. Hope it helped!

LethalSideParting


(stephen2002) #18

that would work, but then rain couldn’t be blocked by the car or the trees. It also would not glint under the glow of the headlights.


(Cessen) #19

Blender jitters each successive frame for the motion blur slightly, so that when they are combined, objects that are not moving in screen-space are anti-aliased. And objects that are moving are blurry, and thus the AA doesn’t matter quite as much (although, depending on the level of quality you want, it still can matter).

You can test this out on your own by rendering a still picture with 16-sample motion blur, and no OSA. And something that’s quite interesting: if you render a still with both 16-sample motion blur and OSA, you get the equivilant of 256-sample anti-aliasing.

I remember this quite vividly, simply because I remember suggesting to Ton that he impliment this into the motion blur feature… and he e-mailed me back saying that it was already there. I felt really stupid that day :slight_smile:


edited – I changed “vididly” to “vividly”


(Nayman) #20

i dont think you realize the nessicity of motion blur

it amkes anythign, no matter how slowmoving, a much more realistic look, definatly wortyh the [email protected]

trust me!

try a small test