# Hemisphere map emitter¶

## Description¶

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

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:

• 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

## Children Nodes¶

 angledistrib The angular light distribution function 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 3.0 example¶

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