Sprites in sunlight and shade

[Eric2575]

I'm working on an outdoor scene that has direct sunlight and some shaded areas. Sprites are flowing from the lighted area into the shaded area, yet the sprites brightness does not diminish as it goes from sunlight to shade? The sprite particle is basically a white blob that stays bright no matter what the lighting conditions are. Can this be changed in the sprites properties? I want the sprites surface to be darker as it moves into the shaded area of the scene.

[Eric2575]

Been playing around with this problem with still no progress. John3D? Caroline? Anyone?

[John Bigboote]

Look to see if the sprite has an ambience setting...it's probably at 100% where you want it at 10 to zero %... methinx

[johnl3d]

Sprites are rendered if i remember correctly last and are not effected by shadows if you know the timing you could adjust the sprite over time to darken later if its life but it might be a bit tricky..I'll try to play with the idea later tonight as time allows

[John Bigboote]

Maybe rendering the sprites separately and then adding them back in in 'post'...

[robcat2075]

If it isn't possible to turn off ambience on a sprite, you may have to resort to using a particle effect that is an actual 3d shape, meaning the new "water". I think those really exist inthe scene and can be shadowed.

 

You'd have to experiment to get a particle setting that mimics what you were doing with sprites, presuming your sprite really was a blob, not a recognizable image.

[Eric2575]

Wow, I was hoping there was something basic I was overlooking. I've got the look of the scene pretty much how I want except for the shadowed areas. It took a lot of time to get to this point. I hope I don't have to redo everything with something different.

 

When opening the sprite material, I don't see any setting for ambiance for the sprite. There is tint, color, and opacity. Even if there was an ambiance setting, this would not work right, since it would be impossible to control the ambiance as the sprite goes from sunshine to shadow. If the sprites themselves are not affected by shadow, as John pointed out, I'm going to either have to use something other than a sprite, or change the direction of the sunlight.

 

I'll see what water blobbies do. Are streaks also not affected by shadows?

 

Edit: As expected, a test confirms that streaks are also impervious to shadows. Since I can't do a search with "3d" sprites in the title, maybe someone has a link to a tutorial on them?

 

Edit: The new water feature will not do what I need it to do, besides, it takes way too long to render even with only one emitter - I have about 20 plus emitters in my scene.

[johnl3d]

instead of ambience look at additive color in the color method

 

 

turned additive off in middle additive.mov glow goes down slight;y

 

 

streaks would be exactly like sprites

[Caroline]

I had a go, just because I was wowed to be mentioned in the same breath as johnl3d. My blobbies appeared to hold a shadow - they looked less bright in the shade, but had the same specular appearance, but sprites would only cast a shadow. I think as robcat says it needs to be something with an actual 3d shape to hold a shadow.

[Fuchur]

Are you able to animate the tinte-color over time?

 

Other than that, the post-approach could really help you. Render only particles out, than the other scene-elements.

Now load everything in for example AfterEffects and determine where the light/dark-borders are.

Draw a mask on a dark color-layer where the particles should look dark. Overlay it over the particles (not the other scene-elements).

 

Now you can animate the mask if your camera is moving, etc.

 

Another way would be to create a dark geometry which will cover the particles in dark areas. Now render this one out. After that, render particles to a separate image-sequence and then render the other stuff to another image-sequence. Now you can use the dark geometry as the coverage and it should work.

It is a little bit annoying, but it should work.

 

*Fuchur*

[robcat2075]

If you have a complex shadow situation I doubt animating the color of the sprite over time will do.

 

I don't suppose a material effector will affect a sprite after it has been born, will it?

[Eric2575]

Caroline, blobbies and water are out due to the increase in render times - my computer pretty much hangs up with the number of instances I need when using blobbies. It's sprites or nothing. Fuchur's idea of an overlay geometry may hold promise, I'll experiment with that and post my results.

[Caroline]

Overlay geometry in A:M could work. Depending on the resolution and quality needed, because this is a bit hazy on the particles.

 

This is a mess, but I don't have a lot of time today, and my particles would not go where I wanted them.

 

The green square is casting that square shadow on the orange. Notice that the 3 particles around the shadow square are a bit darker than the others. The shadow square has no influence on them.

 

As an experiment, I created a square that has a spherical combiner - spherical because I wanted the edges blurred, and i wanted it round so that I could tell what was what. The spherical combiner consists of one circle 100% transparent, the other 70% transparent and grey. They are blurred too.

 

In the picture you can probably make out the circular dark haze above the shadow square.

 

So you could move this square with the transparent material around and make it act like a shadow, and the particles are seen through the 70% transparency.

[johnl3d]

Good suggestion Caroline..

 

also material effectors will not effect particles and they would effect everything else they touched

 

 

 

mateffector.mov

[Caroline]

Maybe if you used material effectors, it could be rendered in layers. I guess particles are OK with an alpha channel render.

[NancyGormezano]

You haven't mentioned what the sprites are supposed to represent - nor if this is for an animation or still ?

 

Perhaps you might be able to use hair instead ? Moving hair emitters that use the image you are using for sprites ? Hair responds to shadows. You can animate the density, length as well.

[Eric2575]

Thinking it through, I believe the answer will be in compositing the scene. If I use semitransparent mesh to cast a shadow on the particels, the area behind the particles that already have shadow on them will also be affected by the screen and will get even darker, not desirable. I'd show you what I am doing, but it's Top Secret, the winning entry in this month's landscape contest

[Caroline]

the winning entry in this month's landscape contest

 

Huh. And you let us help you in all innocence. Never mind - you're going to need all the help you can get

 

Hair is a good idea. That's one of the things that's so great about A:M is there are multiple solutions.

[Eric2575]

Well, I was able to render out just the sprites to a TGA with an Alpha channel. It was a bit tricky getting everything set up just right for the render because the sprites are bouncing off different surfaces. The solution was to group those surfaces and set their properties to transparent. That way the sprites could still bounce, but the background would still be black. The resultant render locks pretty cool. I'll share after the image contest. A slight but correctable drawback is the fact that the usual leakage of the sprites now also rendered behind the transparent bounce surfaces. A couple of dabs with the PS eraser took care of that.

 

Something quite annoying has been happening as I render these sprite intensive images. Since there are so many sprites in my scene, I usually have particles turned off as I am working on the chor. When I test render, I naturally want the particles turned on. The problem lies in the fact that after the render is done, the particles in my chor stay turned on. This in turn makes it almost impossible for me to continue working due to the slowdown. I would have thought that just because you turn on particles in the render, doesn't mean that it would also turn on particles in the chor after the render is finished. Is there a way to avoid having particles turned on by the render settings? Particles in render - Good! Particles in working chor - BAD!

[Fuchur]

I didnt mean to cast a shadow with a object.

I meant overlay the particles with dark(black) geometry. Now render the geometry to one imagessequence. Then render the particles to another. Each one with an Alpha-Channel.

In a Post-programm (for example AfterEffects) you make the dark geometry transparent (for example 30%) and now the underlying particles (which are covered by the transparent geometry) should be darker for 30%.

 

That would work...

*Fuchur*

[Eric2575]

Maybe I'm having a hard time visualizing or understanding how this would be done? The sprites are similar to clouds, semitransparent and all over the place. Think of them as fog rolling over a landscape, passing around the base of a cliff, going from sunlight to shade to sunlight. Everything except the particles are reacting properly to the shaded areas in the scene. The particles remain the same intensity through out. The compositing is taking care of that though.

 

Nancy:

 

This is for a still - I shudder to think the render times with that many sprites for a 30 second clip

[NancyGormezano]

Nancy:

 

This is for a still - I shudder to think the render times with that many sprites for a 30 second clip

 

Then hair (sounds like it's for clouds) might do the trick if you use emitter images (same as your sprite) and comb it "cloud like" - use a variety of shapes for the surface emitting the hair - have it conform to your shape/path of the cloud area - use transparency (render times could be high)

[Eric2575]

Nancy:

 

Geez, now you got me thinking about it!!! Ok, I'll try an experiment with your idea and see if it pans out. Good thing I'm keeping progressive renders of everything I try for comparisons. Will report later.