Since cnpower answered the first part, I'll try the second.
Lux, of course, is the SI unit of illuminance or luminous intensity. It is derived from the lumen and defined as one lux = one lumen per square meter. Thus, lux includes the area over which the luminous flux is spread.
Isolux is a plot or map of that area indicating the light distribution as lines of equal luminance; much like an isobar weather map of lines of equal barometric pressure.
street lighting 
Re: street lighting
