This week, we’re focusing on Houdini’s materials, lighting and rendering.
Displacement rendering
Displacement maps are usually used to represent the height fluctuations of objects in the rendering.
The effect is usually to move the position of the point along the normal of the surface by a distance defined in the map.
It gives texture the ability to express detail and depth.
It can also allow self-covering, self-projection, and edge contour rendering.
On the other hand, compared with other similar technologies, this technology consumes the most performance because it requires a lot of additional geometric information.
Mantra is a highly advanced renderer included with Houdini. It is a multi-paradigm renderer that implements scan lines, ray tracing, and physically-based rendering. You should use a physically-based rendering engine unless you have a good reason to use another engine. Mantra is deeply integrated with Houdini, such as efficient rendering of packed primitives and volumes.
Lighting
Ambient lighting adds light to the scene as if it came from a sphere surrounding the scene. Usually, the light is colored using an image called an environment map. Environment maps can match the lighting (and reflections) of the scene to the real-world position, and can also be used to add interesting changes to the lighting of the scene.
HDR mapping refers to environment mapping with high dynamic range in image software such as 3D. Generally speaking, HDR texture is a “seamless texture” composed of “HDR photos” (seamless texture is a picture where the edges of the picture are connected up, down, left and right, no seams or traces can be seen). HDR textures are generally natural Scenery or indoor environment.
The HDR map has a high dynamic range of the illumination information data image, the normal image is 8bit, and the HDR map is 32bit. In other words, he has more grayscale details and richer details. High dynamic range images are closer to the dynamic range of the human eye, and even exceed the human eye. In short, it is a photo with rich light and dark details. This is an image processing software that makes up for the lack of camera dynamic range, and can take multiple photos with the same position but different exposures at the same time.
8-bit color:
In television, each individual value represents a specific color in a color area. When we talk about 8-bit color, we basically mean that the TV can represent colors from 00000000 to 11111111, with 256 color variations for each value. Since all TVs can represent red, green, and blue values, 256 variations of each color means that the TV can reproduce 256x256x256 colors or a total of 16,777,216 colors. This is considered VGA and has been used as a standard for TVs and monitors for many years.
10-bit color:
10-bit color can represent each of the red, blue, and yellow colors between 0000000000 and 1111111111, which means that it can represent 64 times the 8-bit color. This can reproduce 1024x1024x1024 = 1,073,741,824 colors, which is definitely much more than 8-bit colors. For this reason, many gradients in the image will look smoother, as shown in the image above, 10-bit images are obviously better than 8-bit images.
12-bit color:
The 12-bit color range is from 000000000000 to 1111111111, making the color scale range of 4096 versions of each primary color, or 4096x4096x4096 = 68,719,476,736. Although this is technically a 64 times wider color range than 10-bit color, the TV must produce a bright enough image to see the color difference between the two.
Light object：
Point — A light that emits light from a specific point in space defined by a light transformation.
Line-The line of light from (-0.5, 0, 0) to (0.5, 0, 0) in the space of light.
Grid-a rectangular grid from (-0.5, -0.5, 0) to (0.5, 0.5, 0) in the light space.
Disc-a disc-shaped lamp. The disc is a unit circle in the XY plane in optical space.
Sphere-spherical light. The sphere is a unit sphere in the space of light.
Tube-Tube light. The first parameter of Area Size controls the height of the tube, and the second parameter controls the radius.
Geometry — Use the object specified by the geometry object parameter to define the shape of the area light.
Far-A directional light source at infinite distance from the scene. Light sources in the distance will cast clear shadows, so depth map shadows can be used.
Sun-a finite size (non-point) directional light source at infinite distance from the scene.
Sunlight is similar to high beams, except that they produce penumbras-similar to the actual sun with soft shadow.
Arnold