Explain materials please?

[patseguin]

I am using Indigo as my renderer for Sketchup. I created a scene with a wooden desk using a wood texture from Sketchup. I decided I want to add a little reflection to the surface. How do I do that exactly? There are no options to add reflection to the object. Is there a theory that I should be following to understand it? The one thing I thought of maybe was to duplicate the desk surface object and assign a transparent reflective material to it. Is this kind of layering the way we are meant to texture objects? The same goes for a carpet which I think shines too much. Would I have to place a copy of it on top and then apply a texture using no reflection?

[Oscar J]

No, that's certainly not how you would do it.

I think you need to get a grasp of the basics by watching a couple of tutorials:

https://www.youtube.com/playlist?list=P ... 5118A36995
https://www.youtube.com/playlist?list=P ... A2CD263FE1

There are more tutorials as well as a manual and FAQ under the support section.

[patseguin]

Thanks. I watched those tutorials and they weren't much help. They helped to explain how materials work, but not really how to use them in a real project. It only explains the differences between all the render types.

Here is the scene I am working with:



As an exercise, I am trying to make the monitor a little glossy just like a real iMac's would be. I am selecting the screen and changing it from phong to specular but all that does is give me a black mirror. In sketchup, I tried copy and paste in place and then made the copy specular and 50% transparent but that only gives me a black mirror too. I also tried copying and pasting since I don't really know what paste in place does and the copy only gives me a black mirror. How would I add just a touch of reflection to the monitor while still having the wallpaper texture on the screen?

[Oscar J]

A phong should be fine for the iMac screen. The problem is probably that the phong doesn't have anything to reflect.

Use a black colour for the phong, an IOR of about 1.5, a high exponent value (50 000 or more) and put the screen texture in the emitter slot instead.

To you a transparent specular, you need a volume with the normals pointing outwards, which you would know if you went through the online manual.

http://www.indigorenderer.com/documenta ... ling-glass

[patseguin]

Heh, I will view the videos again. However, I am just not clear on how materials are supposed to work. Phong I believe just makes it shiny. I wanted to add a slight amount of reflectiveness to it. In order to do that, am I meant to make a copy of the screen object and paste it on top and give it a different material setting like specular? I tried that and gave it a black color and 20% transparency but it just covered the screen completely and was solid black. Other renderers I've tried have checkboxes in a material to add reflection, transparency, etc. I like Indigo the best because I've gotten the most realistic images of them all. I just can't figure out how to edit the materials to the way I want.

Another suggestion I had from a friend was to make the rugs not shiny. How would I do that? Would I have to make a copy of them and paste them on top and assign a different type again?

[Oscar J]

But reflectiveness = shiny. Phong materials are useful to make shiny objects with a variety of looks: very rough and subtle reflections (tyres, rubber, etc.), or very clear and sharp reflections (car paints, highly lacquered wooden floors, etc). A black phong with IOR 1.5 and exponent 100 000 should work just fine to approximate the iMac screen (with a texture in the emission channel if you want the screen to be on).

If you despite this want to simulate a glass panel in front of the screen, there are basically three ways to do that.

1. Use the coating material type. You will need to specify a substrate material beneath it, which could be a diffuse or phong material with the screen texture. The coating should have an IOR of 1.5 and very little absorption since it's supposed to be clear glass. This coating material will simulate a thin sheet of glass in front of the LCD panel.

2. Do exactly what you've done already (duplicate the front of the screen and give it a specular material), but use the thin glass material type in Indigo. This is an approximation of a real glass volume, without actually having to create a volume (e.g thickness to the glass sheet).

3. Duplicate the front of the screen and give it thickness (see the glass tutorial I linked before). Use a simple transparent specular with IOR 1.5. This is the scientifically accurate method, though the difference between these three methods in this case should be very small, if not negligible.

The reason for that Indigo gives you better results that other renderers is because it doesn't take those shortcuts in its materials models that you described.

[patseguin]

How does the coating material work? I selected the surface and changed it from phong to coating. I then clicked on the "substrate" button but nothing happened. Beneath and to the right of the substrate button is the word "Map". On the far right is a dropdown box with on explanation of what it is but it appears to be a list of textures. I selected the image on the screen. I then clicked render and got some error about something set to none. What is the substrate button supposed to do?

[Oscar J]

Not a Sketchup user, sorry.

[Pibuz]

Patesguin: visit my blog and you can download several tutorials.
They're in italian but with loads of images. Maybe they can help you out a little.