What is Reflectance?
When it comes to 3D visualization, reflectance is an important consideration. Put simply, reflectance is the measure of how much light is reflected off of a surface. This can have a big impact on how realistic your renderings look, as different materials will have different levels of reflectance.
For example, a metal surface will have a high level of reflectance, while a matte finish will have very little reflectance. By understanding how different materials reflect light, you can create more realistic renders that are true to life.
In addition to material type, the angle at which light hits a surface can also affect reflectance. A surface that is perpendicular to the light source will have less reflectance than one that is at an angle. This is why you often see light bouncing off of surfaces in real life, but not in renders.