This week I started to create a model of the scene. As I have a lot of projects this semester, I will create just one exterior scene of the town to test the stained glass material and the rendered image. I also want one side of the town to be stained glass and the other side to be uncolored glass. So for the outside of the town, I will design half of the scene to be a stained glass building with an exaggerated shape and the other half to be a more regular colorless building.
Here are some of the reference images I found for the scene:
This is the first version of the scene model:
The second version of the scene model: (I reduced some buildings in order to test the materials and lighting of the scene as soon as possible. And I also modified the wiring)
Yann and I shared a video on the creation of the material for the stained glass.
This video is interesting and in summary, the author shares with us the use of textures to create light coming through the model. After using the base material model, add colored images to the [texture] in the [transmission] section so that the light shows colored light when it hits the model. This might be suitable for me when creating interior scenes, as I have a plot design where the furniture in the house glows with colored candy when the candy on the tabletop shines on the scene inside.
For this outdoor scene, because of the large number of models, too much-colored light can cause the models to reflect light that is uncomfortable to look at. Therefore, I will create a different color of colored glass on each model and consider reducing the glass’s transparency to reduce the amount of light cast from the houses. As I intend to create the outdoor scenes separately from the indoor scenes, this will reduce the number of faces on the model.
For the exploration of glass materials:
Material is the essential material on the surface of an object, such as wood, plastic, metal or glass. Among the various materials used in 3D models, glass is often used and is a difficult material to represent. Many CG designers make glass materials that are not ideal. The designer in the creative process is completely dependent on personal feelings and subjective understanding of things, directly with a material ball for parameter adjustment. Still, the final effect of rendering and the actual glass material is very different. Therefore, we should first analyze the physical properties of the glass and its parameters and then test and adjust them in the software according to our analysis and understanding. To analyze the physical properties of glass, we should start with perceptual cognition and rational analysis: 1. Perceptual cognition of glass, first of all from the visual perception of transparent, reflective, high-gloss. A rational analysis of glass materials should include more scientific knowledge of physical theory. For example, the refractive index of glass and the conservation of light energy, etc., but also through the Internet or other literature to find its physical properties.
The more important properties of glass are refractive index close to 1.6, the reflectivity of approximately 15%, incident light energy = reflected light energy + transmitted light (regardless of absorption) in addition to glass also has the Fresnel effect. The French physicist Fresnel found that the amount of light reflected from a surface is related to the viewing angle when looking at it. When the line of sight is perpendicular to the object’s surface, the reflection is weaker and the transparency is higher. In contrast, when the line of sight is not perpendicular to the surface, the reflection is stronger and the transparency is lower. What causes the difference in the amount of reflected light is the angle of the viewing glass.
The following is a brief analysis of how to use MAYA to achieve a more realistic glass material.
First, determine the basic material sphere because the surface of the glass material is brighter and more reflective, so use MAYA’s Blinn material sphere as the base material for the glass. Then, you need to adjust the values of the Blinn material sphere. The process of creating the glass material should be based on the physical properties and then add artistic embellishments.
The color property should be black or near black. Although, in reality, glass looks mostly transparent and colorless or close to colorless, there is a gap between software and reality, and the physical properties here are only used as a reference direction, and the parametric properties in the software are not fully equivalent to the physical properties. For reasons of mya software implementation algorithm and a lot of practice tests, it is concluded that, in general, the color is black or close to black, whether it is made of glass or metal.
Transparency is the physical property of transparency, which is known to be around 15% reflective, so the transparency setting here can be close to 85%. However, because glass has a Fresnel effect, the material’s transparency must have a gradation from strong to weak from the viewer’s line of sight perpendicular to the object to parallel to the object. So you must use the light and dark of the ramp map color parameter, i.e., select color, to control the average value of the ramp map’s select color, which is approximately 85 percent. If you want to get a stained glass effect, you can also adjust the transparency color directly. I will test this by simply giving the glass material some color first.
The Diffuse property, because glass is transparent, most of the light will be transmitted out of the object, so the Diffuse parameter is very small and can be set to around 0.3 for now.
Eccentricity, this parameter controls the range of highlights. Decreasing the value of this property here will result in a smaller range of highlights and a smoother surface for the glass.
Specular roll of (high light intensity), glass should have stronger and sharper highlights, so this parameter should be increased appropriately.
Specular color, white or grey, represents the highlight color determined by the light source color and is the most commonly used and most natural. White or slightly greyish is used here. It is important to note that colored highlights are only available for metallic surfaces.
Reflectivity (reflectivity), the physical properties of glass reflectivity, is 15%. So the parameters here can be close to that value. Still, because of the Fresnel effect, the reflectivity here should also be gradual. Use the amp mapping color light and dark to control the change in its parameters, just like the transparency gradient control above.
Refractive index (refractive index), the previous physical properties of the analysis already know the refractive index of glass, directly adjusted to about 1.6 can be.
Refraction limit, which requires an analysis of the actual refraction of light in the glass bottle.
The higher the Refraction limit, the whiter and brighter the entire bottle material will be, and vice versa, the darker it will be.
If you want to get the ideal glass material, not only do you need to adjust the material sphere itself carefully, but you also need to set the light and render it correctly. Otherwise, you need to check the refraction box in the renderer settings. Otherwise, the light will not be refracted in the glass.
I will be working on the glass material settings and lighting next week.
Summary of this week:
This week I completed the creation of the scene models. I deliberately created the houses on both sides of the street differently during the scene design. I wanted the stained glass buildings to have a more interesting shape and the colorless buildings to have a more rigid Cube shape. This way, when creating the materials for the models, there will be an interesting shape in addition to the different materials later on. In addition, it helps to add some artistic detail to the lighting renders.
I also explored some glass materials and learned about the parameters. I think this will help me to create better materials and lighting for my scenes.