Materials Editor Panel

This is probably the most important panel in Owlet. Here you can configure materials to make your scene looking the way you need. Here’s what it looks like:

Owlet materials editor panel

The panel consists of three blocks:

  • Material preview - the area where you can see the currently edited material rendered on a standard shape;
  • Material tree - here you can find the tree of groups and layers that make the material;
  • Parameters - the rest is the parameters of the currently selected item in the material tree.

Materials editor displays the properties of the currently selected material. You can select material by clicking an object in the scene, or directly in the scene materials list. Materials editor displays the currently selected material in its title, so you always know what you edit.

Material Structure

It is described in more details here, but in two words materials consist of groups, each group is made up of layers. Owlet traces material layer by layer to render a surface.

Materials editor displays these groups and layers in the material tree, which has medium properties in its root node, then come groups and finally layers. By clicking items in the materials tree you see their properties at the right (or at the bottom for the narrow panel).

Main Parameters

Main parameters of Owlet material

Here you define the medium properties of the material. It means the inside of the object covered by material. Say if you need a glass ball, you need to define the glass transparency and refraction exactly here. Below is the list of parameters:

  • Bump - here you can define offset bump texture which gives perfect results on flat surfaces, the bump level is measured in centimeters;
  • Double-sided - controls if the mesh is visible from both sides. For instance if a signle-side material is assigned to a plane, the plane will be transparent from one side. Checked by default;
  • Medium - lets you choose between None, Manual, Measured and Opaque medium modes. See below for more details.

Depending on the Medium parameter you can also see some of those:

  • N - the index of refraction of the current medium (Manual mode);
  • Absorption - the color of the medium. Do not use 100% values in any of the color channels as otherwise you’ll get no absorption, except for the white color if you don’t need absorption at all. (Manual mode);
  • Attenuation - this controls the amount of absorption depending on the medium thickness (Manual mode);
  • IOR File - lets you specify a file containing the measurements of index of refraction parameters for various wavelengths. It works slower, but provides better results (Measured mode);
  • Priority - this controls what medium to use if two shapes overlap. The one with a higher priority is used then (Manual and Measured modes).

There is also optional Subsurface scattering section that lets you make various plastics, skin, wax, milk and so on. It comes with three parameters:

  • Color - controls the probability of photon to hit the inside of the medium. You’d better keep it gray, as using colors makes it quite unpredictable. However, sometimes color is a must there;
  • Scale - controls the amount of the effect;
  • Asymmetry - controls if the reflected photons run through or out the shape.

Material Group

Groups are used to group layers and also add masks. Here’s what the group settings look like:

Owlet material group settings

The Mask option controls the visibility of the whole group. If the mask is black, the whole group is invisible (transparent) to rays. Masks can be used to create complex patterns on materials (rust areas on metal, for instance);

Material Layer

Layers are probably the most important part of the whole material. See here for more details on how they work, here we’ll briefly run through all the properties.

Owlet material diffuse layer settings

First of all, each layer has a type. The type can be either Diffuse, Fresnel or Measured Data. Diffuse layers are probably the simplest ones and here’s the list of their options:

  • Mask - the same as with groups, you can mask out some parts of the layer to make it completely transparent for rays;
  • Bump - that’s a simple normal-based bump working on both flat and non-flat surfaces, the bump level is measured in centimeters.
  • Diffuse layer - the option enables the “diffuse” behavior of the layer;
  • Color - this is the most important parameter of the layer, as it defines its color. You can also assign a texture, of course;
  • Opacity - controls if photons can run through the layer or not. This is sort of a subsurface scattering for layers and is usually used for making paper, leaves and so on;
  • Transmission - this controls how much rays go down to the next layer of the material. You can tint them and even apply a texture, if you like;

Here’s what you see if you switch to the Specular layer type:

Owlet material fresnel layer settings

Specular layers are the reflective ones, so we’ve got more parameters here controlling reflection. Here are the parameters:

  • Reflection - same as for the diffuse block, lets you control the reflection tint;
  • Transmission - again, same as above this controls what goes to the next layer;
  • IOR - lets you choose between “plastic” and “metallic” reflection and also lets you specify a special “IOR file” with measured material properties;
  • N and K - these parameters define the index of refraction of the layer;
  • Reflection 90 Level - defines how much of reflected rays look different if reflected by the right angle;
  • Reflection 90 - provides an alternative reflection color and image for right angle reflections;
  • Roughness - controls the reflection blur of the layer, the more rough (uneven) the layer, the blurry the reflection;
  • Anisotropy - controls the level of anisotropy effect;
  • Angle - controls the direction of anisotropy (angle), works best with a proper texture, Owlet has some in the materials library.

Specular layers also have optional thin-film interference options (think of soap bubble, oil on water or color-coated sunglasses). Here are the extra options you’ve got:

  • Thickness - the base thickness of the thin layer (measured in nanometers);
  • Min Thickness - activates if the Thickness parameter gets a texture, so the Min thickness becomes the minimum value, while the Thickness values are added to it;
  • IOR - lets you select the way Owlet computes interference. The options are: Scalar, Complex and Measured data.

For the Scalar mode Owlet provides N parameter, for Complex mode both N and K are provided and for the Measured data you need to load an IOR file with all the measurements.

Finally, the last supported type of layers is the Measured data one:

Owlet material measured data layer settings

Compared to the fresnel layer type, there are no reflection parametes, N and K parameters are also absent. Instead, you need to load IOR file that defines all the missing parameters. Owlet comes with some sample files in its materials library.