How to create specular surface in Mitsuba Renderer I am a newbie in computer graphics and I am trying to develop a special case of path tracing really slowly! But first: I came up studying the Mitsuba renderer and one of its uses in the so-called GDPT (Gradient Domain Path Tracer). I am trying to build a Cornell Box in this framework and my silly problem arises in realizing which kind of material is a "mirror". In simpler words: I want a mirroring sphere in my scene but I don't manage to create it. According to the documentation that you can find here (http://www.mitsuba-renderer.org/releases/current/documentation.pdf) we can have all the different surfaces explained in section 8.2, which are:


Smooth Diffuse material (diffuse)
Rough diffuse material (roughdiffuse) 
Smooth dielectric material (dielectric)
Thin dielectric material (thindielectric)
Rough dielectric material  (roughdielectric)
Smooth conductor (conductor)
Rough conductor material (roughconductor)
Smooth plastic material (plastic)
Rough   plastic material (roughplastic)
Smooth dielectric coating (coating)
Rough dielectric coating (roughcoating)


Can you please help me understand what set of parameters will make a mirroring surface material?

Usually for each kind of material there is a reference XML code (which is what I am using to build the scene). Therefore, the main question remains understanding how to build a mirror, but please take those examples in considerations because the parameters in those are the only things I can tune. Thanks in advance!
You want to use the "conductor" plugin to create a smooth conductor / metal type BRDF. See section 8.2.6 in the documentation.

As far as Mitsuba is concerned, a mirror is a special instance of a metal, where the material is specified as "none" (which corresponds to using complex IOR of $ \eta = 0 $ and $ k = 1 $).

Here is an example in xml:

&lt;shape type="..."&gt;
    &lt;bsdf type="conductor"&gt;
        &lt;string name="material" value="none"/&gt;
    &lt;/bsdf&gt;
&lt;shape&gt;