8 Replies Latest reply on Nov 2, 2017 4:58 PM by Mark Jackson

    IOR Values for Many Materials

    Mark Jackson
    Mark Jackson Nov 2, 2017 8:32 AM

      Hi Guys,

       

      I was searching the forum for IOR and didn't find anything like this, so I thought I'd share it with you all. It's a site with a list of hundreds of materials and their IOR values. Hopefully it's helpful for a few of you. Or, if anyone knows of better lists or sites, please pass them along.

       

      IOR / Index of Refraction List - Pixel and Poly

       

      -Mark

        • Re: IOR Values for Many Materials
          Rich Fagioli
          Rich Fagioli Nov 2, 2017 10:50 AM (in response to Mark Jackson)

          Thanks Mark...but an index of refraction is only useful for light transmission, not so much for light reflection which is what most of rendering surfaces is concerned with. In the time I've worked with Visualize, I've only tweaked an IOR for varying thicknesses of clear plastic and glass. And even where I've rendered spectroscopy lenses of pretty esoteric materials, adjusting the Visualize IOR setting did diddly-squat.

            • Re: IOR Values for Many Materials
              Mark Jackson
              Mark Jackson Nov 2, 2017 11:30 AM (in response to Rich Fagioli)

              Hi Rich, I'm having a hard time with material appearances in Visualize. Nothing seems to be that intuitive or work the way I expect it to work. So the IOR in Visualize is only refractive? It's not also linked to Fresnel IOR that would work on metal surfaces and the like? The table I submitted is supposed to be for both in the world of 3D rendering. Other rendering software has IOR and Fresnel IOR linked. Some let you unlink them and adjust separately if you want.

                • Re: IOR Values for Many Materials
                  Rich Fagioli
                  Rich Fagioli Nov 2, 2017 11:48 AM (in response to Mark Jackson)

                  IOR will become important when looking through clear materials at very acute angles. Recall how thick eyeglass lenses will bend a persons face at the edges of the lens, or how standing outside of and looking through curved car windshield distorts the map left on the dashboard. Adjusting the IOR will help create a more realistic see-through "experience".

                   

                  Your difficulty in creating accurate surface reflections is almost certainly due to application of environment lighting. It's tough nut to crack, and will require a lot of practice! Lot's of very useful info in this forum, though....

                   

                  As for that table of IOR values, a mineralogist will use a lot of that info to help identify and isolate a specific mineral under a light microscope. I wouldn't bother seeking out that info for its direct application in Visualize. Just slide the values around until you get what you want!

                    • Re: IOR Values for Many Materials
                      Mark Jackson
                      Mark Jackson Nov 2, 2017 12:08 PM (in response to Rich Fagioli)

                      I hear what you're saying Rich. I'm not fond of moving sliders until I get what I want with no clear understanding of what the slider is supposed to do, and how it's supposed to behave. If I understand what the parameter is and how its supposed to behave, I'm a lot more confident that I'll get the result I want and in a timely manner. I'm not at that point in Visualize.

                       

                      The other thing I don't get is that the IOR table from Pixel and Poly is specifically to help people get realistic reflections on materials in 3D applications. I'm also doing work in Blender and have conversations with the Blender community about realistically rendering materials, and two of the main things discussed are using real world IOR values and using a linear workflow. Linear workflow and gamma are a whole other conversation that I won't start here. Maybe another thread later, but back to IOR. Why does a table like the one from Pixel and Poly seem to have a lot of value in other 3D applications, but not in Visualize?

                        • Re: IOR Values for Many Materials
                          Rich Fagioli
                          Rich Fagioli Nov 2, 2017 12:45 PM (in response to Mark Jackson)
                          Why does a table like the one from Pixel and Poly seem to have a lot of value in other 3D applications, but not in Visualize?

                          I'm not sure, Mark. You may want to search for IOR in Visualize "Help". I think that you'll find that the limited areas in which the IOR is adjusted, means such a detailed table is simply "Too Much Information".

                            • Re: IOR Values for Many Materials
                              Mark Jackson
                              Mark Jackson Nov 2, 2017 1:08 PM (in response to Rich Fagioli)

                              Ah, the definition of the IOR parameter you provided Rich does seem to imply a connection between the refractive IOR and Fresnel IOR of material albeit indirectly. How I can turn that into something I understand about the parameter and how it should function in detail remains to be seen.

                               

                              Thanks for taking the time to discuss this with me Rich.

                    • Re: IOR Values for Many Materials
                      Dave Goetsch
                      Dave Goetsch Nov 2, 2017 4:51 PM (in response to Mark Jackson)

                      The ability to tweak IOR allows you to create very realistic gems among other things. If you check out the basic Diamond appearance you will see it looks nothing like the image below. Only very careful tweaking of the parameters, including IOR, will achieve this....

                       

                      Diamonds5.png