Lens Flares Come from Where?

  • I am wondering where lens flares come from? They don't come from emissive materials and Enscape lights are not visible, so where exactly do they come from, if at all? I use recessed cans with an emitter material as the lens quite often and would like flares to show up from them. Any tricks for this?

  • That's a very good question! I haven't messed with flare since it doesn't seem to make much of any effect in the image. Doing a quick test, it looks like it just gives you a flare from the center of the camera, regardless of where the lighting source is. I think maybe what you're missing is the effect of having a star shape around each light source in the image (I'm attaching a V-Ray render for reference.) I don't see any way to get this kind of flare in an Enscape image.

  • There is a misunderstanding. There are two different phenomena:

    Lens flare: This describes various reflections within the lens optics of a camera. The so called "ghosts" of a light source are placed towards the image center.


    Glare: These are the little "stars" you are talking about that come from imperfections on the lens surface or the camera chip.



    In Enscape: We support lens flares for all bright surfaces. We support glare in a special case for the sun (the star that you see when you look into it) and bloom for all bright surfaces. The "gaussian" style bloom in Enscape is not as beautiful as what you get in a camera (or offline raytracers) with the little star shapes. This is subject to improvement!

  • Thanks for the explainer! I guess I would have to add the "star" glare in post if I want that. So the flare is kind of like chromatic abberation - a type of lens imperfection to add some interest to the images, but it doesn't take into account specific light sources like bloom and glare do?

    Do put me down for a +1 for adding glare shapes in Enscape.

  • So the flare is kind of like chromatic abberation - a type of lens imperfection to add some interest to the images, but it doesn't take into account specific light sources like bloom and glare do?

    It does. Maybe your test image was too confusing because it has light sources everywhere. Note that with "light source", I mean a bright surface. Just an artificial light floating in the air does nothing on it's own, it always needs a surface to interact with.


    ! I guess I would have to add the "star" glare in post if I want that.

    I'm sure that you can do this quite nicely, especially if you base the glare stuff on the HDR output. But that's none of my/our expertise ;)

  • That was the one model that had the strongest artificial light sources. The flare barely shows up in other scenes with artificial lighting. I know it shows up when I have an outdoor scene with the sun visible, I was just testing what it did when there are multiple light sources - that was when I discovered it doesn't actually respond like the way I was hoping.

  • I am wondering where lens flares come from? They don't come from emissive materials and Enscape lights are not visible, so where exactly do they come from, if at all? I use recessed cans with an emitter material as the lens quite often and would like flares to show up from them. Any tricks for this?

    So lens flares or the "star" effect seen in photography or render engines such as VRay are a directly cause from the camera and its parameters. In VRay for example, this effect is cause by the number of blades set for the aperture - aperture being the f-number. These blades produce the glare effect aka the starburst. VRay allows you to set the size of the aperture ie f-number same as an F-stop on a real camera. This "F" value is the size opening of the aperture. The number of blades are what creates the opening by sliding together forming a "circle". All of this works identically to our eye. The more light our eyes are exposed to the smaller our pupils get and the less light the more open they become. So, in a camera the user has to control the dilatation -(opening and closing) of the blades in front of the camera's senor ie the f-stop. The star effects is produced by the light reflection off the blades and the number of blades a camera has will determine the number of points the "star" effect has. The exposure and intensity of the light will determines the strength of this effect. A similar effect can be made with our eye by squinting. try squinting at a street or traffic light at night. The light will streak due to the reflection off our eye leashes. Our eye leashes create an obstruction on our pupils producing an imperfect glare. These effect can also be recreated in camera by having dust or scratches on the lens or in VRay by piping in a black and white texture map in the "glare image". This will cause an imperfect glare which is something more desirable making the render appear less 3D perfect.

    Enscape is currently simulating more of the human eye which is nearly perfect and doesn't have the faceting so we get a more uniformed blur. So in order for Enscape to do what a real world camera produces it needs to simulate a physical camera by settings values for the f stop and the number of blades. By doing this it will make the glare effect more accurate to a real world camera. ISO and shutter speed also need to taken into account as the can have an effect.

    Hopefully this provide you with a better understanding =D