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Creating glassy refractive surfaces

From: SketchUp Rendering Using Twilight

Video: Creating glassy refractive surfaces

As glass is one of a handful material types that we come into contact with pretty much every day, the chances that we will want or need to re-create it in our scenes really are quite high. In this video, we're going to work at creating a couple of slightly different glass types, really as a way of demonstrating how we create refractive materials using the Twilight renderer. The first material we will create is a glazing material. Now, we need of course glazing geometry to apply that material to, so I just want to come up to my Window menu, down to the Layers option, and in the Layers dialog, I need to unhide the Patio Glass and the Skylight Glass layers.

Creating glassy refractive surfaces

As glass is one of a handful material types that we come into contact with pretty much every day, the chances that we will want or need to re-create it in our scenes really are quite high. In this video, we're going to work at creating a couple of slightly different glass types, really as a way of demonstrating how we create refractive materials using the Twilight renderer. The first material we will create is a glazing material. Now, we need of course glazing geometry to apply that material to, so I just want to come up to my Window menu, down to the Layers option, and in the Layers dialog, I need to unhide the Patio Glass and the Skylight Glass layers.

With those pieces of geometry in the scene, I do want to go and select them. So I am just going to middle-mouse-click and orbit a little bit around our view. Then I am just going to middle-mouse-scroll out, just until we can see all of our glazing geometry. Then I am just going to left-click to select one and then hold Ctrl and then just left-click to select all of the other pieces. Once that's selected, I can just go back to my glazing camera. Really, we've just selected those so that we can easily apply our new material to them once we've created it. To do that, we're again going to need our SketchUp Material browser, so let's come into that.

I am just going to go and check our In Model options, and I just want to select our default gray material. This really is because when we create a new material in SketchUp it takes the definition of the already selected material and applies that to our new material. If we have our default gray material selected, then we have no bitmaps that need the clearing out. So with that material selected, I am just going to go and click on the Create Material icon. Again, we're going to give our material a name, and we're going to call this Glazing, and then we can just click OK.

Now, we can just simply left-mouse-click and apply that material to all of our selected geometry. Now, what we need to do of course is apply a template to our newly created material. So let's close the SketchUp browser. I am just going to use spacebar to return to my normal Select tool, and I am going to come up to the Twilight toolbar and click on the Material Editor icon. Once that opens, we do of course need to go and select our material in the scene. I am just going to use the Material Select tool in this instance. I just left-click our Glazing geometry. With the default gray material loaded in, we of course need to go and apply a material template.

If we just come up to the Templates menu and come down, you can see we essentially have two options available to us, so far as glass is concerned. We have Realistic Glass, which gives us reflections and refractions from the material, and we have our Architectural Glass, which gives us reflections but not refractions. The reason this Architectural Glass set exists is just to save us a little bit on render time. With glazing, the refraction is so imperceptible, more often than not, that it makes sense to cut that path off the material calculation out.

So, we're going to use the Architectural Glass set in this case. So if I just left-click on that, and we're going to come in. And we're going to use this Common option. As you can see, our material preview updates and shows us that we do have a transparent or see-through material. Of course while the material preview can be useful, it is no substitute for a test render, so that's what we'll go and take. Again, because we have geometry selected in the scene, we're being asked if we want to render only that geometry. Of course, with glass we want to make certain that it is reflecting the environment around it, so we are going to say no.

As easily as that, we get a very nice glazing material. You can even see the physical accuracy of this material at work in the reflections as the viewing angle gets steeper. Looking at these pieces of geometry down at the far end, you can see that the reflectivity increases just that little bit. So as we see, very nice, very easy to create this glazing material. Now, if we just come back into our Material Editor, you will see that there really are three parameters that are creating this material for us. We have our diffuse color that is contributing somewhat to the overall finish.

We have our Alpha option, which is essentially controlling the transparency of our material. With the Alpha set at 100, we have a completely opaque or solid- looking surface; if we set our alpha at 0, we have a completely transparent material. We also have this extremely important Index of Refraction option. Now, as we've mentioned that the Architectural Glass templates don't actually give us any refraction, that part of the material definition has been removed, you may wonder whether this value actually has any relevance.

Well, if we just set our IOR value to 1, we can show you the relevance that it has, by taking another render. The result we get is an almost completely transparent material, so transparent that it really doesn't look as if we have any window geometry in the scene. We get this result because Twilight materials have physically correct Fresnel equations built into them. These equations govern the look of both reflections and refractions in a material. In a see-through material, such as glass or water, the Index of Refraction value will determine the amount of reflection versus the amount of refraction, or in this case the amount of transparency, seen in the material.

Seeing then as the reflective aspect of these equations is still very much at work in these Architectural Glass templates, that's why the Index of Refraction value is still extremely important. Before we move on of course, we do want to go and reset our Index of Refraction value. If you are not certain what the physically accurate value was that was set, then we just need to come back up to our templates, come back to Architectural Glass, and reapply the Common option. So creating a clear glass material is pretty easy to do using Twilight's Material templates.

How though would we go about adding some color to our glass? Well, although with the default materials and libraries that install with Twilight we have no way to create a physically accurate colored glass-- that is, one whose color will to some extent be determined by the volume of the geometry it is applied to-- we can still go and create a quick pseudo version. To do that, we will of course need an object to apply our material to, so I am just going to close my dialogs and then come and switch my scene camera over to our butterfly garden ornament.

This piece of geometry makes the perfect candidate for applying a colored glass effect too. Again of course we need to walk through the process of creating a new SketchUp material. In this instance, I will make certain that our glazing material is selected before I go and use the Create Material button. In the Create Material dialog, I will go and instantly name our material. So we will call this Colored Glass and then click OK. And with the Paint Bucket tool still active, we can just click to apply that to our butterfly geometry. We do of course need to apply our material template, so let's close SketchUp Material Browser and open up our Twilight Material Editor.

And again, I will just use the Material Selection tool to pull my material definition into the Material Editor-- although in this instance I don't want to make use of the Architectural Glass option. With a piece of geometry that has so much volume and thickness to it, we really would expect to see some refraction occurring inside this piece of glass. Because of this, when we come to our template options, we really want to work with the Realistic Glass set in this instance. So let's just click on that. And I think we will choose something a little bit different; we will work with the Light Frosted option.

Straight away we can check our material preview, just to see what kind of effect this particular option will give us. We do still need to add our coloration, so we need to come up to our Diffuse Color controls, click on the Material swatch, and I think in this instance, we'll choose something in the orange spectrum. And we can just make that a little bit darker. Now because this is a fake, meaning that the coloration does not grow stronger in thicker parts of the geometry, I would suggest keeping our saturation values fairly low and our luminance values reasonably high.

If we have too much coloration, too much saturation in our color choice, we can tend to get some very, very strong color effects in our glass of course. If that is what you want, then that is absolutely fine. In this instance, I am going to set my saturation all the way down to a value of 75, and I will keep my Luminance at a value of 125. Now, if this is not the color you want, don't be overly concerned because as soon as we click OK, you will see that this really isn't the color that we end up with in our glass material. And as soon as our material preview updates you can see the coloration is looking quite a bit different.

Still, if you want to make some changes, feel free; you can really set whatever color you like at this point. Again, to see what kind of effect, what kind of material this will give us, we do need a test render. As you can see, we get a fairly nice colored glass effect from our material. Clearly, we can see that it lacks physical accuracy; where we have these thicker parts of our butterfly's body, they should really be deep and vibrant in color, and of course these thin areas should be almost colorless in terms of how we would expect real glass to look. But still, nevertheless, a fairly nice effect in the end.

If you're wondering about the extremely increased render times, this essentially is because of our Frosted Glass effect. Really, Twilight is having to perform blurred refraction calculations inside of the geometry volume, so it's not surprising that it will take a little bit of time to produce that effect. Ultimately though, the good news for us is that Twilight's Material templates have made the creation of our very different glass materials very simple, very easy indeed. Not that we're finished with our refractive materials mind you! In our next video, we're going to look at how we can go about creating our pool water.

Show transcript

This video is part of

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SketchUp Rendering Using Twilight

33 video lessons · 4510 viewers

Brian Bradley
Author

 
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  1. 4m 1s
    1. Welcome
      1m 5s
    2. What you should know
      2m 10s
    3. Using the exercise files
      46s
  2. 6m 53s
    1. Installing the Twilight renderer
      2m 52s
    2. Locating Twilight tools and features
      4m 1s
  3. 50m 22s
    1. Adding the Physical Sun and Sky
      6m 17s
    2. Employing the Point light type
      6m 35s
    3. Using the Spot and Projector light types
      7m 7s
    4. Adding the IES light type
      3m 48s
    5. Using light-emitting materials
      6m 59s
    6. Creating image-based lighting using High Dynamic Range Images (HDRIs)
      6m 12s
    7. Using Sky Portals for interior global illumination (GI)
      6m 43s
    8. Understanding the importance of reflectance in materials
      6m 41s
  4. 21m 54s
    1. Exploring Light Transport options in Twilight
      9m 18s
    2. Managing the Quality presets
      5m 57s
    3. Editing and saving presets
      6m 39s
  5. 22m 8s
    1. Positioning your scene view
      3m 23s
    2. Altering projection types
      5m 12s
    3. Working with depth of field
      3m 59s
    4. Working with focal length
      2m 44s
    5. Harnessing tone mapping, exposure, and gamma
      3m 59s
    6. Using two-point perspective correction
      2m 51s
  6. 38m 13s
    1. Introduction to Twilight materials
      8m 23s
    2. Creating diffuse surfaces
      6m 53s
    3. Creating reflective surfaces
      6m 53s
    4. Creating glassy refractive surfaces
      9m 28s
    5. Creating watery refractive surfaces
      6m 36s
  7. 31m 28s
    1. Rendering for animation
      8m 55s
    2. Rendering out an alpha mask
      3m 44s
    3. Setting up a depth render
      4m 3s
    4. Creating an RGB mask using the Diffuse Texture Pass preset
      5m 45s
    5. Working with a composite
      9m 1s
  8. 1m 13s
    1. What's next?
      1m 13s

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