“Lights and Shadows”, 2020-07-01 ():
[Tutorial on illumination & geometry with interactive JS widgets for visualizing ray-casting of lights and shadows. Topics: light power, position, logarithmic perception, distance & angle governing intensity (‘irradiance’), radians, casting onto spheres, luminance, reflections, and color.]
It’s hard to describe how paramount light is. Ultimately, it is the only thing we see. But just as important the presence of light is, so is its absence. To talk about light we have to start in darkness so let’s jump straight into it. Light is a visible portion of electromagnetic radiation, but in this article I’m not going to discuss any of the underlying details like wave-particle duality. Instead, I’ll try to explain how light creates so many beautiful effects seen in everyday life. In the demonstration below you can use the sliders to control the position and size of a rectangular light source. You can also drag around the scene to see it from different angles…