Texturing the Bar Stool

Understanding what makes a realistic material

01. Texturing the Bar Stool with Wood and Leather

For this exercise we’re going to create a wood from a real world example and go over some visual cues that can help you identify material values.

First thing I always do when trying to deconstruct a real-world object is look at the highlights and any reflections on an object. This will tell me 3 things: Reflectivity, R.Glossiness and Fresnel values. I ignore the wood in this case (the Diffuse map) because I want to know how the light is reflecting off the surface. Take away the Diffuse and this could be the start of any other material.

The highlights on this product are reflecting back a light source and telling me this surface is moderately glossy. You can tell because the highlight doesn’t spread far from the brightest point. If you look closer you can see that the highlight isn’t perfectly smooth either so the wood grain, or other surface imperfection, is breaking it up. So we know we’ll need a map in the R.Glossiness too. Another way to tell if something has a high R.Gloss is if any reflections are clearly identifiable in the object. Here we can make out the legs in the reflection on the underside of the seat.

The reflectivity of the surface is basically how much it bounces back the surrounding environment. The higher the value the more mirror like it becomes. This chair appears to be very reflective because we’re able to see the white studio environment reflected back from a lot of angles. If it weren’t as reflective you would see more of the wood material instead. Again, it appears there is something breaking up the reflection as these areas vary from light to dark.

Fresnel IOR controls the angle reflections can be seen at. One way to visualize it is that it’s pulling or pushing the reflection across the surface from your view. A metal floor has a high IOR (18-50) because reflections come right to your feet. While a wooden floor has a lower IOR (4-6) because the reflections stop before reaching you. In the image on the right the sphere is reflective from every angle with an IOR of 50, but only at the far edges with an IOR of 1.3.

Assigning Material IDs

The first thing to notice about the wood in this SKU is that it is two different colors! So we will need to assign two different Material IDs to these areas of the legs – the sides and the top and bottom. If you forgot how to do this, refer to Section, “Multi/Sub Objects & Material ID’s”.

Once you’ve done this you will need to create a Multi/Sub Object Material and apply it to the chair body. Then plug the materials that we will be creating into the proper material slots!

Making a Wood Material

So using the approach outlined above let’s enter some values into a new VRayMtl and see what we get:

  • Reflect at 230 (since it’s reflective, but not mirror like)
  • R.Glossiness at .75 (reflections/highlights are clear, but slightly blurred)
  • Fresnel IOR at 4.5 (reflections at grazing angles)
  • GGX falloff at 1.8 (highlights appear soft at the edges)

Without any maps you should have a preview that looks like the right image. Since the material preview isn’t 100% accurate and doesn’t show scale it’s best to test on the model at the same time.

We can see it has similar properties compared to the real photo under similar lighting (see left). Something to take note; you won’t be creating materials under the same lighting conditions the reference imagery was taken so highlights may not be in the same spots, but what matters is they look the same.

Next take the wood texture you will be using in the diffuse and apply a Color Correct node to make our bump and reflect maps. In Color Correction set the channel to Monochrome to make it B&W. In the Lightness rollout at the bottom click Advanced to open more options. The options in this tab are explained below:

RGB/R/G/B: You can change the settings for all three color channels simultaneously and for each channel individually.

Gamma/Contrast: The amount of gamma adjusts contrast. Increasing the gamma exponent decreases contrast.

Pivot: Gamma correction is applied about a pivot value. That is, pixel values equal to the pivot value are left unchanged. This is useful when you want to use gamma correction to change the contrast of an map but do not want to affect a particular luminance level.

Making a Wood Material (con’t)

We’re going to make 2 copies of the Color Correct node, that both come off of the diffuse, and change the values of the Gamma/Contrast and Pivot for each to get variation in the reflectivity and bump, and use a noise map for R.Glossiness. Try to match the following images below for reflect, glossiness and bump:

Our wood looks very smooth in the reference photo so these maps are having little effect on the overall surface variation. So the strength of these in the VRayMtl map slots should be set low. Experiment with the values to see the differences and don’t be afraid to use extreme values just to see what you’re changing. Turn off other maps so they don’t confuse the end result you’re looking for.

It’s easy to make things look perfect in 3D so your goal is to push for more imperfections and variation in the surfaces of objects as counter-intuitive as that sounds.

Your render should look similar to the image on the right.

Your material setup should look like the image below:

Making a Wood Material (con’t)

Now we can connect the noodles of the original texture to the Diffuse Map slot of each material to see how all our settings work and make any adjustments needed. If you need to adjust the colors of the diffuse textures you can add a Color Correction node.

Making a Leather Material

We’ll be using the same example and approach as with the wood and creating a leather without the diffuse first.

There’s many types of leather with different properties. Some can be created simply with a color in the diffuse and a bump map, others have detailed grain variations that require use of a blend material, and some even use anisotropy because the reflection stretches across the surface.

The type we’ll be recreating is on the easier end of leathers and only needs some bump and reflective maps.

Let’s start with the following values:

  • Diffuse color RGB 2,2,1
  • Reflect at 246
  • R.Glossiness at .5
  • Fresnel IOR at 5
  • GGX falloff at 2.5
  • Anisotropy .3

You’ll notice in the render to the right our values look correct but the geometry for the padding shape is different along with the lighting. This is acceptable because our values are acting similar to the example image so you shouldn’t feel the need to try and replicate exact characteristics of the reference image (ex: the large darker area in the reference photo).

Changes in a products appearance happen during manufacturing so not all wood or leather grain will be the same. You should strive to get as close as possible.

For the grain we’ll be using a bitmap, but it’s entirely possible to create a leather grain with procedural maps. This gives you full control over the size, pattern and variation, plus it’s seamless by default.

Making a Leather Material (con’t)

I’ve used a greyscale image of leather and placed that in the bump and reflect maps of the material. Since we’ve created a diffuse with a color value we only need to create the surface texture of the leather. The bump strength is set high (60) so we really see the detail in the grain. It’s also instanced into the reflect slot to give us some variation in how strong the light bounces off the surface. A noise map (scale at .08) is in the R.Glossiness slot (strength at 100) to, again, make the reflectivity not so uniform across the surface.

Final Render

With what we covered across the past few pages you should have a result similar to this:

02. Material Exercise

Create the wood, leather and painted metal material for CSTD4951 using the processes outlined above. For the metal of the crossbeam, refer back to Section 04-03. You can get all the textures and the final model file from this link.