Français
82
APPENDIX 2: DETERMINATION OF REFLECTED
TEMPERATURE
The relevant standard is ASTM E1933-99A:
1) A sheet of ordinary aluminium foil, crumpled and flattened, is placed as close as
possible to the scene viewed, in the same orientation with respect to the camera.
2)
It is assumed that the sheet of aluminium is a perfect reflector on which is reflected
a black body equivalent to the mean environment.
The emissivity setting of the camera is therefore:
ε
= 1
3) The temperature of the black body equivalent to the environment is measured on
the sheet of aluminium, using an appropriate analysis tool - spot with averaging
over several positions or, better still, the mean calculated over a large area.
4) This Reflected Temperature must be entered into the computer by hand. It
becomes active when the emissivity of a real object is less than 1.
ε
= 1
English
Summary of Contents for C.A 1875
Page 99: ...Fran ais 98 English...
