# Single photometric illuminance measurement. Light should be assumed to be

# measured along the sensor's x-axis (the area of detection is the y-z plane).

# The illuminance should have a 0 or positive value and be received with

# the sensor's +X axis pointing toward the light source.

# Photometric illuminance is the measure of the human eye's sensitivity of the

# intensity of light encountering or passing through a surface.

# All other Photometric and Radiometric measurements should

# not use this message.

# This message cannot represent:

# Luminous intensity (candela/light source output)

# Luminance (nits/light output per area)

# Irradiance (watt/area), etc.

Header header # timestamp is the time the illuminance was measured

# frame_id is the location and direction of the reading

float64 illuminance # Measurement of the Photometric Illuminance in Lux.

float64 variance # 0 is interpreted as variance unknown