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Category: Lighting
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Autor: Next Limit Technologies
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Studio Lighting tips
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Many principles of photography can
be applied to Maxwell Render and
these tips will try and show you some
common lighting techniques in a studio
environment, and things to consider
when lighting transparent and reflective
objects like glass and metal.
Regarding the emitters, it can be useful
in many cases to avoid the evenly lit
area of the emitter surface by making
a gradient texture in any image editing
application and converting that texture
into an mxi using MXCL, then applying
the mxi to an emitter material. The mxi
emitter used in all these renders looks
like this:
With glass being very transparent, it can be difficult to
light it in a way that brings out it’s shape, and creates a
contrast with it’s background. The following two studio
setups will show you two approaches which you can
build upon to render attractive looking glass objects.
In the following render four emitters where used,
placed in such a way as to light up the contours of the glass to bring out it’s shape but without
making the reflections too harsh or obtrusive.
Sharp side reflections of the lights was avoided using an mxi texture applied to the emitters, and
the emitters strength was adjusted during rendering using Maxwells multi light feature.
The next page shows the scene and emitter placement.
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Left emitter was set pretty low to
only give a hint of the shape and
keep the reflection of the emitter
nice and smooth.
Same thing with the emitter on the
right.
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The top emitter was tilted forward
a bit to properly light up the rim of
the glass.
The backdrop has a hole in it, a
bit smaller than the foot of the
glass. A small emitter was placed
beneath the hole to light up just
the foot of the glass. This way
the emitter doesn’t cast any big
disturbing reflections on the rest
of the glass.
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With a light grey or white backdrop,
the same studio setup as for the
black back drop might not work
too well, since everything in the
scene will look white including
the edges of the glass making it
blend into the background.
To avoid that just make sure
you have something of a darker
color in the scene for the glass
to reflect. In this case since the
environment is already black,
the emitters where simply moved
farther away from the backdrop
so there’s a bigger area of black around the glass.
It is important to note that moving the emitters farther away will not make the specular reflections
lose their strength. Specular reflections will be just as bright, no matter how far the emitter is.
This is good to keep in mind because if in some cases you find an emitter is casting too strong
light on your background, instead of dimming it using the multi light slider (which would also dim
the specular reflections on the object), you can simply move the emitter farther away.
The left emitter was also scaled in Y to give a longer reflection in the glass.
The hole and small emitter wouldn’t be necessary if you’re rendering on a light background, but
in this case it was kept because it made some interesting strong reflections in the foot of the
glass.
Metallic objects can also pose
a problem because of their high
specular reflectiveness.
Lets say in this render, the metal
blade looks just like you want,
but the background is too dark.
Increasing the emitter strength
would make the metall turn fully
white, and moving the emitter
closer is not possible.
In this case you can take
advantage of the fact that highly
specular reflective surfaces
will bounce the light rays at the
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same angle at which they hit it.
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In more precise terms: the angle
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reflectance. In practice this means
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that the emitter must be placed
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at a certain angle relative to the
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camera, if you want that emitter
to be reflected by the metal.
If we place another emitter
outside of this angle of incidence
relative to the camera, it’s rays
will not reach the camera, and
so that emitter will not contribute
anything to alter the brightness of
the metal.
The image on the left illustrates this. You can see that this second emitter does not influence the
metal at all, while it helps to brighten up the background.
The light rays reflected in
a specular way from the
object, do not reach the
camera, thus the camera is
“blind” to this emitter.
The result is, the knife blade has the exact same intensity but the background is brightened up
by the second emitter, while also adding a nice highlight on the knife handle.