Need help with Turning Spot Light into Headlight Beam
Turk_WLF
Posts: 177
I’m sure that I’m not the only one that has tried to use Spot Light “Bulb” in Carrara 8 Pro. Where I need help is with the settings like the Half Angle, Angular Falloff/Range, and Range Falloff. I don’t want to use the Light Cone. I have a Quad-Headlight setup with 2 High/Low Headlights & 2 just High Headlights.
My ultimate goal is to have a realistic headlight feel from both “drive-by” & a Driver’s Viewpoints.
Thanks,
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Spot light and bulb are two different lights in Carrara, you can add any lights as you want (don't forget the ambiant light), but only one must cast shadows if it's a sunny day.
Inside a room, that depend of the internal lightning.
If it's for a still image, you can check the global illumination to have a more realistic render.
The shadows are never at 100% and diffuse depend of the "weather" in your scene.
All depend of your taste...
Turk_WLF, I just made a quick test using geometry for the beams and put Spot Lights at the end. I turned off Cast Shadows and Receive Shadow for the beams. I tried matching the Half Angle of the Spots to match the end of the beams, but I don't know if that is correct, maybe they should be wider.
If something like this is what you have in mind, I can post the file. It does use light cones but I have them fade very quickly.
Sorry for using the horrible El Camino from the Carrara stock library, but hey, it fit the bill.
If you want "realistic" I suggest you first start with some photos of headlights. Below is a photo of headlights at night in a very foggy environment.
The reason why this happens is that the light beams bounce off the water/other particles in the air and into your eyes. The more fog/water/dust/whatever in the air, the more pronounced the light beams.
Also keep in mind, as the photo shows, car headlight beams are generally NOT uniform at all. They are generally not a uniform circular cone, because headlights are designed to throw more light in some areas and less in others. And they are not perfect devices.
And when it is very foggy, the area that is illuminated is more than just the "light beam" area from the headlamp, it's also areas that are illuminated by the light bouncing off the moisture in front of the car, so you get more of a general glow area.
So first you need to decide what you want to simulate...lots of fog/dust/particles, or just a little, etc.
You might try using an IES file to get the ground lighting looking correct. You can find a ton of them for free all over the internet: there's a zip of some along with a picture of what they look like in this thread: https://www.keyshot.com/forum/index.php?topic=7077.0
Also, a really interesting and not too technical discussion of how a car headlight works, IES light profiles and so on - I just skimmed it and mostly looked at the pictures but there might be some helpful stuff in there: http://www.kineticorp.com/publications/2010-01-0292-photometric-headlamp-light-distribution.pdf :)
Excellent advice. IES files are, IMO, the most useful but under-used lighting feature in Carrara.
Personally, I think the challenge with light beams is to convert the IES profile into a gobo-type modifier on a light cone effect. And I think I'd tend to try to do that in a 2D compositing app. Not sure if Carrara's light beams are up to the task. Although Mark's results are very nice.
If your offer to post the file is open to someone other than the OP, I would be interested. I always enjoy learning and seeing a variety of approaches to the same end.
Note that, without using a light cone effect you won't get any visible light beams without shining them through an atmosphere of some kind, unless you attach a similar, faked sort of effect of your own.
That being said,
Half Angle - gives the width of the cone of light
Angle Falloff - fades the edge of the lighting effect
Distance - regulates how far the lighting effect can travel
Distance Falloff - fades the far edge of the distance lighting effect
Default Spot Light comes in with a Half Angle of 45, which is far too wide for a normal car headlight. I don't recall the range I most often used, but it was much lower. Then I usually went for an angular falloff of around 33 or so. For some lighting effects, a distance falloff of 100 works really great since it begins to gradually drop off of intensity right from the start. So I didn't use 100 for my cars headlights, since I always wanted them to hold their ground a bit before falling off. Something more like 67%, depending upon the distance set and the effect needed.
I always used the light cone effect on mine, but kept the intensity somewhat low, and also diminished the intensity further with the falloff setting in the cone effect, which can easily eliminate the effect altogether with even a fairly low setting, so start low and work upwards with that, if you try it. I also preferred to use the turbulence setting, and alter the scale and intensity according to the weather conditions. I would then set the spotlight to ignore the car so that I could sink the light far enough into the vehicle to have the effect start at the appropriate diameter instead of a single point. If I needed a light inside the glass of the light fixture, I used a second light for that, often a tiny bulb light.
Low-density volumetric clouds can make for a beautiful fog effect, but I've not tried it against the light from a spotlight to be used instead of the cone effect. I've always been one to try for the fastest renders possible, and the cone effect is much faster than v-clouds. At least in the scenes I was using.
For a significant fog, I think my approach would be outside of the Carrara realm. I would tend to employ a volumetric fog, generated in a compositing app, along with a light beam effect generated in the same compositing app. I find that gives a LOT more flexibility than the stock Carrara light beams, which, for me, appear far too uniform and "plastic".
The only time you get significant beams is when there is significant fog/dust in the air, so that pretty much calls for a volumetric fog for starters. Too often I've seen light cones used, where the environment surrounding the light cones has no glow from the fog. Doesn't make physical sense...
True, but I've never really needed the effect as a main point of attraction, just to add a subtle touch to sell the lights - so I keep it very subtle - usually. But again... most of my animations are not trying for realism, just fun.
I have a better example on my other computer, but this one does show how subtle I usually go with it.
EDIT: The flares were done in post, but not the light cones
I usually use three or four effects when creating headlights, flashlights, etc. All can be rendered out for compositing by using render passes and/or an alpha channel.
For the light itself, I use a spot, and if I need it to be less than perfect, such as dark spots or uneven illumination, I use a gel. The light cone can also use the light's gel, so you could avoid the shadow option and the light through transparency option in the light cone editor. Speaking of which, I sometimes use a light cone, but sometimes I use a volumetric cloud for the effect.
Along with the gel, and the light cone (or cloud), I also use the 3D light sphere, set to realistic. This can help to hide the point origin of the spot light. I also sometimes use a lens flare. If the car is moving towards you from a distance and approaching, you may need to keyframe the intensity and the diameter of the flare as the light approaches, otherwise it will be uniform throughout the animation.
For the light cone, intensity and falloff are the real key. If you don't have enough falloff or the intensity is high, the edges of the cone are very apparent. This video uses a high light cone falloff and a lower light cone intensity. I also use the light sphere and a lens flare. I do believe in this one that I forgot to keyframe the lens flare intensity and diameter and the effect is far to strong. As the ship approaches however, you can see the subtle light cones.
https://www.youtube.com/watch?v=QN6E8ji3oHA
The attached images also use the lens flare and 3D light sphere to sell the light effect. The space ship and astronaut image uses volumetric clouds and no light cone, whereas the other images use the light cone.
Note that a gel can also define the shape of the light emitted by the spot light, so you could make a square light, or a slit type light.
Very nice images, as always, ep!
@kakman, Here you go: https://www.dropbox.com/s/jx58gvqj3l5jsr5/Headlights.car?dl=0
I will have at least learned 3 things with this thread:
1- what it is a “headlight”
2- to re-examine my English vocabulary
3- not to trust my memory, especially when it's so hot weather… No no, don't laugh dear friends…
Nice exemples all these images !
Mark,
Thank you very much.
Hi Turk :)
Have you tried using Fog to create the "Light Beam's" ?
Use the scale tool to re-shape the fog primitive,.... choose "Cylinder" or "Box" as the Fog prmitive type..
Ok, it appears that my originally I didn't make my original posting clear enough for that I'm Sorry. Maybe if I explain how I do my light(s) it might help, let's I'm doing a flashlight (I model the reflector seperately with a mirror shader) . I use a bulb "light" (with it set just to shine on the reflector only) and a seperate spotlight "light" to do the "boardcast" the light or to act as the "beam" of the flashlight & I need help with settings of the spotlight.
I hope this will clear things up & I'm grateful for all of the help so far...
Thanks,
Hi,
I do that for my film, here is a picture without postwork and the seeting of the bulb.
Any smoke or clouds, a lens flare only.
Okay, it sounds like you're trying to model a physically realistic light with a bulb and reflector, and you're expecting the renderer to calculate the light rays from the bulb light bouncing off the mirrored reflector and give a realistic light beam.
If that's the case, keep in mind that the Carrara renderer is not a physically based renderer, and doesn't calculate bounce light like that. You'll have to fake it, depending on the results you want.
Here's an example of a physically modelled and rendered bulb with reflector. In this case I used the Blender Cycles renderer. I made a simple, spherical bulb with the front-facing half of the sphere set to black, and the rear-facing half (which faces the reflector) is an emission material which emits light like a real light bulb. The reflector was just a hemi-sphere with a reflective material.
This shows that even though the front facing side of the bulb isn't emitting any light, the floor in front of the bulb/reflector is fully lit, solely by the action of the bouce light off the reflector.
And notice that a light "aura" envelopes the main light beam, and there is a realistic falloff with distance from the light.
Now if you wanted to get real fancy you could also model a glass cover, with all of its imperfections and refractions, to get a super realistic headlight.
And since the REAL key to reproducing reality is IMPERFECTIONS....
I re-did the render with only one minor tweak...reproducing the minor imperfections you see in almost any flashlight/headlight/whatever reflector. I just edited the reflector mesh and tweaked some polygons so the reflector wasn't a super perfect sphere. Cuz nothing in the real world is ever super perfect. And the result is a FAR more believable light pattern.
The Light Beams "Effect" is due to the illumination of particles in the air, by a light source. Nothing to do with lights or reflectors or mirrored surfaces.
Shine a flashlight in a clear dust free room, no beam of light, just the source and the resulting Illuminated area
Do the same in a dusty or foggy environment and you'll see a thick visible "Beam" of (particles in the air illumunated by the light source)
Andy, if you read his two posts, you'll see that he says: "I don’t want to use the Light Cone", and "My ultimate goal is to have a realistic headlight feel from both “drive-by” & a Driver’s Viewpoints."
And then in his clarification he says: " I'm doing a flashlight (I model the reflector seperately with a mirror shader) . I use a bulb "light" (with it set just to shine on the reflector only) and a seperate spotlight "light" to do the "boardcast" the light or to act as the "beam" of the flashlight
While his goal of "realistic" is unclear, nowhere does he clearly say that he's doing a dusty/foggy environment visible beam. However he clearly says he's trying to model an actual bulb and reflector to obtain his flashlight beam. Hence my explanation of why he might be unsuccesful trying to do that in Carrara, and how he CAN make that model work using a different type of renderer. So yes, what the OP is doing has a LOT to do with lights, reflectors, and mirrored surfaces.
Until he clarifies further, I think it's still unclear if he's trying to obtain a visible dusty environment beam or just have some success with his bulb and reflector.
By the way, I've noticed over the years that one effect that seems to be WAY overused in general 3D renders is the visible light beams effect. In real life, if you think about it, it's relatively rare to have an environment that has enough dust or smoke or water droplets to cause visible beams. And a lot of renders have visible beams only in the area of the light beam, but the surrounding environment doesn't show the same haze.
Just one of those areas that makes viewers kinda scratch their heads trying to figure what's wrong with that image... :)
Yeah, but who cares about realism anyhow?
Realism is for prople who can't handle fantasyism!
One reason I suggested that if one is looking for a "visible beam" effect then I'd try to do it in a 2D app is this:
As is clear from the photo I posted above of the car headlights at night, if the environment is truly filled with enough dust, moisture, smoke, etc. to cause visible beams, then the entire area in front of the car has a bit of glow. This is due to the light bouncing off the particles in the air and making everything kinda "glowy".
So to illustrate I took the last image I posted of a Blender render of a physically based bulb and reflector, and brought that into a compositing app. This app has a cool "volume rays" feature which gives you incredible flexibility in defining the fuzziness, overall glow, etc., of the rays it produces. And you can watch the changes in real time and select what you want.
Here's a simple animation
http://youtu.be/pz85ydQcSDw
If I read your question correctly, you need help understanding the settings for the spotlight.
- Half Angle refers to the degrees/angle of spread for the light (i.e. think of it as the geometry of the light "cone")
- Angular Falloff is used to "soften" the effects of the light on the edges of the spot (light decay). the greater the % value, the less lighting effect there is toward the outside edges of the "cone".
- Range Falloff is similar to angular falloff only it affects how intense the light effect is for the entire range of the light. The higher the value, the "faster" or sooner the light decays
I've included a few examples below so you can see what the settings do.
It's hard give specific values that would be best for your situation, but and easy way to see what how the different settings will effect your scene would be to shine a spot light onto a black plane at about a 70 degree angle (with no other lights in the scene).
You may also be able to get the effect you want by setting up a "real" light like you described. This probably wouldn't be good for animation, as you will need to enable full ray tracing and indirect lighting, so render times would be greater. I also attached a couple of images using this method. The inside surface of the light is reflective, I have a bulb light in it, a "lens" and a light restictor cap to help narrow the spread angle of the reflector cone. Carrara has some really good indirect lighting capabilities with path/ray tracing, so in many respects it comes close to un-biased render engines (also known as PBR or Physically Based Render .... the "new" buzz word for un-biased renderers).
I've also attached the file with the scene setup I used for the sample images in case you want to explore it a bit on your own. Hopefully all this helps in some way.
Oh.... I almost forgot to mention, should you need a "PBR" in the future, but don't feel like learning Blender, there are some outstanding options available for Carrara. There is Luxus for Carrara (http://www.daz3d.com/luxus-for-carrara) that provides an interface to export your scenes to LuxRender. There is LuxusCore for Carrara (http://www.daz3d.com/forums/discussion/50130/luxuscore-carrara/p1) that integrates LuxCore with Carrara (currently in beta and free). Finally, there is Octane Render for Carrara, my personal favorite, but it is rather costly (and extremely fast).
Nice, comprehensive response Dustrider...
If we keep at it maybe we'll figure out what question he's actually asking.
lol!!
But just think of how much we'll learn in our quest!