25 March 2009

Specular bloom

Hi! Today I will talk about the specular bloom. For those who don't what it is, it is an effect that occur on certain picture were the light hit a white surface or a highly lite surface. The effect look like an emission of light blurred by the object.

Neil Blevins on his tutorial about it say:

''Specular Bloom (also called Diffuse Glow, Bloom, Glow, Ghosts, Flare, Glares) is what we call it when the bright objects in your scene glow. This happens in real photography for a number of different reasons, bright areas can be so bright that the actual emulsion of the film bleeds, bright objects can cause internal reflections inside your camera lens causing lens artifacts from glow to lens flares, the photographer has placed a special "soft filter" over the lens, the photographer has placed vaseline on his lens to give their photo that "soft" look. Simulating this effect in cg is actually pretty straight forward, and helps remove some of that "cg" look from your images.''

As it is said in the last sentences, this is a effect that can be add to improve your render and giving it a more realistic look as our eyes are use to saw this effect in real life and on photos. Personally I think it improve a lot the lighting of a scene. Even if you do a simple scanline renderer it add a lot to the final result. Here are some picture that Ive done with the specular bloom so you can see by yourself what we are talking about.

This picture that Ive done that you already see in a previous post is a scanline render. In this one I use the specular bloom plug in. You can see most of the effect were the light is strong on the brick of the column. You see the blooming effect is blurring the detail as if we were blown by the light.

I prepare also a little render with the effect way to exaggerate. SO here is the infamous teapot in all his glory! I write last night on my facebook status that I was doing tutorial with teapot and a friend of mine answered that I was Teapotizing!! Very funny guy! :O)

The two render are from the same scene and the same camera shot with the same lighting setup. The first is without specular bloom and the second with the effect added. You can definitely see how where the light reach an object more strongly the effect appear. Obviously the effect in not applied correctly here and I could have use it more subtlety but I wanted to show it very clearly.

I use it a lot but we must use it carefully if not it will look to much like an effect and what we want to achieve in using it will be cancel. It is about the same phenomenon as for the filter and effect in photoshop if you use it to much people will notice it and it is bad... You know when people can already tell what filter you have use... But when use correctly people will told you that you did an amazing job with the lighting!!

Now you want to know how to achieve it. In 3ds max you can use two different way to achieve it. The first is by using the specular bloom plug in. You surely can find it easily on the Internet if not try to contact me. It is a nice plug in where you can achieve also 3 more light effect as haze, stocking and glow. They all affect the bright area and the lighting but in different way. Very cool to use, sometimes I use the stocking effect to do fog. You just have to install the plugin in the right folder and then restart 3ds max, hit the 8 button, that give you the environment & effects roll out. Then you go on the effect onglet hit add and then you should be able to add the specular bloom effect. To use it you activate it and you do a render then you will see the effect add at the end. If you use the interactive button then you could now work with the settings to achieve the wanted effect without redoing every time a full render.

If you do not have or find the specular bloom you can still achieve the same result. You just have to use the already install plug in name blur. Do you remind when I said that the effect was a blurring effect? With the blur effect you can blur all your render but it is not want we want. We just want to blur area where the light is very bright when hitting object and surfaces. So you see two onglet, the first is Blur type and the second is pixel selection. Hit the second onglet, so we dont want to affect the whole image as by default but only the light so we unchecked whole image and just check the luminescence box. Now the blurring and bleeding effect will only be achieve on the very bright area regarding how the setting are.

So this is it for the specular bloom effect. I don't really know if you can use it in Maya or other software but I do know that in Maya we got a build in material effect call glow. If I recall well it does about the same if not try to affect the luminescence in the render. I think that there is a place where you can do it but it has been a while since Ive not open Maya!

Sam the 3d blogger

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