Hemisphere map emitter

Description

../../../_images/hemispheremap.jpg

Scene lit by a hemishphere map emitter, based on measurements of the green state of a LCD monitor.

Emitter This emitter uses an hemispherical image as the radiance distribution in all directions over the surface. It is therefore possible to model very complex emission distributions, such as LCD monitors.

The hemispherical projection may be either equidistant or equisolid. The edges of the image are mapped to 90° by default (resulting in 180°, or full hemispheric distribution), but can be mapped to smaller angles.

The image values may be either interpreted as radiance or radiant intensity, or the values may be normalized to other photometric quantities, using the photometry parameter:

  • Radiance Map handles the image values as radiance

  • Radiant Intensity handles the image values as radiant intensity

  • Lumen Value normalizes the map values so that each scene object emits this amount of light.

  • Lux Value normalizes the map values so that the surface emits this luminous flux.

  • Watt Value normalizes the map values so that each scene object emits this amount of energy.

  • W/m² Value normalizes the map values so that the surface emits this energy flux.

The image values, after being converted to a spectrum depending on its format (see Image), is multiplied by the base spectrum. To keep the image values unchanged, for instance when the image contains spectral values or colorimetric XYZ data, you can set base to a uniform spectrum of value 1.

Note

Using this feature requires an Advanced Edition license

Children Nodes

Image angledistrib

The angular light distribution function

Spectrum base

The base emission spectrum

Parameters

name

type

description

projection

real

The hemispherical projection mode

thetamax

real

The normal angle mapped to the edges of the spherical image, between 0 and 90°

photometry

real

Sets the photometry normalization mode

multiplier

real

Avalable only with non normalizing photometry modes (Radiant and Radiant intensity) Multiplies image values by this factor

value

real

Avalable only with normalizing photometry modes. Sets the corresponding normalizing value.

Ocean XML 6.1 example

<emitter type="hemispheremap" name="emitter" projection="equidistant" thetamax="90" photometry="lumen" value="50">
     <image type="file" name="map" path="green_3.exr"/>
     <spectrum type="uniform" name="base" value="1"/>
</emitter>