<p>You want to use the "conductor" plugin to create a smooth conductor / metal type BRDF. See section 8.2.6 in the documentation.</p>

<p>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 $).</p>

<p>Here is an example in xml:</p>

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

CC BY-SA 3.0
2016-08-08T23:02:33.933Z
Already tried that case unfortunately.. it's the sphere on the image you can find here: http://imgur.com/a/2unOE . Which seems quite metal-ish but not really a mirror unfortunately
Tarta
CC BY-SA 3.0
2016-08-08T23:22:30.820Z
Hm. Weird. What kind of integrator are you using to render this image? Maybe share your hole scene xml file so I can try to reproduce it?
tizian
CC BY-SA 3.0
2016-08-08T23:29:55.183Z
I am using <integrator type="path"/> . I downloaded a scene from the website of the Mitsuba renderer itself, implementing a simple cornell box. I just added there my simple sphere. You can find the whole XML here (https://www.dropbox.com/s/qzjuzyg3bont7od/cbox.xml?dl=0) and at the end of the file my simple added sphere.. thanks in advance!
Tarta
CC BY-SA 3.0
2016-08-08T23:41:32.327Z
Here is a rendering using your scene: https://www.dropbox.com/s/k1s825tkus2s4yk/tarta.png?dl=0
Looks good to me.
Did you render the scene? Your image looks a lot like the OpenGL preview at the start...
tizian
CC BY-SA 3.0
2016-08-08T23:44:47.603Z
I am ashamed..you are totally right. I thought it was already the render itself, while it was just a preview. I am sorry..
Tarta
CC BY-SA 3.0
2016-08-08T23:45:26.873Z
No worries. Glad to help :)
tizian
CC BY-SA 3.0
2016-08-08T23:47:38.850Z
thanks once mroe! One last question: I don't know if you are familiar with the GDPT algorithm that Mitsuba renders.. but I was trying to understand if it is realtime and I was basing my judgement on the preview.. thinking wrongly that it was real-time. Then you made me realise that I have actually to render the image, and the real-time thing seems going away. Do you know by any chance anything about this?
Tarta
CC BY-SA 3.0
2016-08-09T00:11:34.623Z
No sorry, I'm not familiar with GDPT at all.. didn't even know this was implemented in Mitsuba.
tizian
CC BY-SA 3.0
2016-08-08T20:45:30.130Z
2016-08-08T20:45:30.130Z
tizian
<p>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 (<a href="http://www.mitsuba-renderer.org/releases/current/documentation.pdf" rel="nofollow noreferrer">http://www.mitsuba-renderer.org/releases/current/documentation.pdf</a>) we can have all the different surfaces explained in section 8.2, which are:</p>

<ul>
<li>Smooth Diffuse material (diffuse)</li>
<li>Rough diffuse material (roughdiffuse) </li>
<li>Smooth dielectric material (dielectric)</li>
<li>Thin dielectric material (thindielectric)</li>
<li>Rough dielectric material  (roughdielectric)</li>
<li>Smooth conductor (conductor)</li>
<li>Rough conductor material (roughconductor)</li>
<li>Smooth plastic material (plastic)</li>
<li>Rough   plastic material (roughplastic)</li>
<li>Smooth dielectric coating (coating)</li>
<li>Rough dielectric coating (roughcoating)</li>
</ul>

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

<p>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!</p>

CC BY-SA 3.0
2016-08-08T19:46:47.540Z
Did you try the smooth conductor?
joojaa
<rendering><specular><subsurface-scattering>
How to create specular surface in Mitsuba Renderer
Tarta
# How to create specular surface in Mitsuba Renderer

(Asked by: username_0 on 2016-08-08)

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!

**Tags:** rendering, specular, subsurface-scattering

> **Comments:**
> **username_1**: Did you try the smooth conductor?  

---

## 1 answers

### Answer by username_2 on 2016-08-08. Score: 6 | Accepted answer

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:

```
<shape type="...">
    <bsdf type="conductor">
        <string name="material" value="none"/>
    </bsdf>
<shape>

```

> **Comments:**
> **username_0**: Already tried that case unfortunately.. it's the sphere on the image you can find here: http://imgur.com/a/2unOE . Which seems quite metal-ish but not really a mirror unfortunately  
> **username_2**: Hm. Weird. What kind of integrator are you using to render this image? Maybe share your hole scene xml file so I can try to reproduce it?  
> **username_0**: I am using <integrator type="path"/> . I downloaded a scene from the website of the Mitsuba renderer itself, implementing a simple cornell box. I just added there my simple sphere. You can find the whole XML here (https://www.dropbox.com/s/qzjuzyg3bont7od/cbox.xml?dl=0) and at the end of the file my simple added sphere.. thanks in advance!  
> **username_2**: Here is a rendering using your scene: https://www.dropbox.com/s/k1s825tkus2s4yk/username_0.png?dl=0 Looks good to me. Did you render the scene? Your image looks a lot like the OpenGL preview at the start...  
> **username_0**: I am ashamed..you are totally right. I thought it was already the render itself, while it was just a preview. I am sorry..  
> **username_2**: No worries. Glad to help :)  
> **username_0**: thanks once mroe! One last question: I don't know if you are familiar with the GDPT algorithm that Mitsuba renders.. but I was trying to understand if it is realtime and I was basing my judgement on the preview.. thinking wrongly that it was real-time. Then you made me realise that I have actually to render the image, and the real-time thing seems going away. Do you know by any chance anything about this?  
> **username_2**: No sorry, I'm not familiar with GDPT at all.. didn't even know this was implemented in Mitsuba.  

---

