How bright is a light bulb?

DaltonSpence

I've been experimenting with a lighted dungeon (actually a lighted railcar but I used that template) and I was wondering if anyone has worked out the light entity characteristics (radius, intensity and color) of modern electric light bulbs (40w, 60w, 100w, 120w, etc.).

jslayton

There isn't a physical relationship between wattage and area illuminated because you also need distance from the light to the illuminated surface, and CC3 doesn't have all of that information. For example, a 60 watt light bulb two feet off the floor illuminates a different area than the same bulb ten feet off the floor.

What CC3's point light system does is to create a really crude height map of the surface using the "Wall Shadow, Point Light Setup" effects and then the "Wall Shadow, Point Light Finalize" effect casts rays in a circle from each light defined with ADDLIGHT. When the ray hits a blocker, it stops the light. The subsystem is really a simple visibility calculation with some extra parts in there to get apparent illumination falloff and colored lighting. One thing to note is what's NOT in the model: a full calculation for illumination from a physical light source to a physical surface (not even a hint of lumens or heights for lights). If you want a 60 watt bulb two feet off the floor, you as the artist have to make a smaller, brighter light; if you want a 60 watt bulb ten feet off the floor, you need to make a bigger, dimmer light.

As is so often the case for the more esoteric CC3+ effects, it was the simplest thing that I could make work in a way that was at least somewhat useful in terms of quality and execution time. And I've learned a lot since then and hardware has gotten a lot better, but breaking people's maps is still Very Bad.

Loopysue

The dungeon lighting system isn't really geared up to imitate particular watages. I do these things by eye.

Come to think of it the intensity of light measured by watage is probably not standard these days. It used to be before we started using things other than old fashioned incandescent light bulbs, but not anymore.

But maybe I'm wrong, and Joe will be along to explain how it is related ;)

jslayton

There isn't a physical relationship between wattage and area illuminated because you also need distance from the light to the illuminated surface, and CC3 doesn't have all of that information. For example, a 60 watt light bulb two feet off the floor illuminates a different area than the same bulb ten feet off the floor.

What CC3's point light system does is to create a really crude height map of the surface using the "Wall Shadow, Point Light Setup" effects and then the "Wall Shadow, Point Light Finalize" effect casts rays in a circle from each light defined with ADDLIGHT. When the ray hits a blocker, it stops the light. The subsystem is really a simple visibility calculation with some extra parts in there to get apparent illumination falloff and colored lighting. One thing to note is what's NOT in the model: a full calculation for illumination from a physical light source to a physical surface (not even a hint of lumens or heights for lights). If you want a 60 watt bulb two feet off the floor, you as the artist have to make a smaller, brighter light; if you want a 60 watt bulb ten feet off the floor, you need to make a bigger, dimmer light.

As is so often the case for the more esoteric CC3+ effects, it was the simplest thing that I could make work in a way that was at least somewhat useful in terms of quality and execution time. And I've learned a lot since then and hardware has gotten a lot better, but breaking people's maps is still Very Bad.