reflections in floors

[madmax_cg]

Quick question...I'm having trouble assigning reflections to stone or concrete floors...Since these materials are not too reflective, I would like to have a low reflection...
What are the Fresnel IOR/Reflect IOR/ Fresnel Multiplier Parameters to achieve a not too reflective surface? I tried lowering the IOR number but got exactly the opposite result of what I wanted...

Thanks for the help!

[dalomar_cg]

Re: reflections in floors

Here's the low down on fresnel...

There are two ways to change the reflectivity of an object within the fresnel settings. The first is IOR and the second is to adjust the colors (or values) that are used.

IOR is the most "physically correct" way of adjusting the reflection level. So lower values (approaching 1) will yield a less reflective material and higher values will make it more reflective. So for lower reflection I would decrease the IOR from 1.55 (the default) to something like 1.2 or 1.3. Also you should change both the IOR values that you see within the fresnel settings to keep things accurate

A chart for IOR values can be found here

The second is to adjust the colors (which translates into the values) that are used when calculating the fresnel result. There are two colors that you see within the fresnel options, and like options like transparency, a gray scale color is used instead of a value with black being 0 and white being 1. The top color is actually what will be the maximum reflection value. This means that the extremes of the fresnel function, which translates to glancing angles of an object, the amount of reflection that is used is dictated by that color. The bottom color is the minimum reflection value. So at the point on the object where the normal points directly back at you, that is the value that will be used.

Now that we know what those colors actually do, we can use them to adjust the appearance of our reflections. In your case you want to decrease the reflections, so you can change the top color (which by default is set to 75% gray or 190,190,190) to 126,126,126 or 50% gray. This will decrease your reflections simply by changing what they will be at the maximum. The converse approach can also be used and is good for some metal materials. For those you can set the top color to white (since metals are very reflective) and the bottom color to some thing higher than pure black (in the case of metals 50% gray works quite well) meaning that overall, your material will have a lot of reflectivity.

That should get you going for now...play around with each method and see how each one works for you. You can combine the two, but I recommend having a good knowledge of how each one acts individually before you go down that road.

[madmax_cg]

Re: reflections in floors

Damien

Thanks a lot for your advice...It can't be any clearer than this.

I'll give it a try!

[dalomar_cg]

Re: reflections in floors

NP...the last level to this is to work with maps within fresnel...thats a few steps down the road, so get the previous stuff down first ;D