Spherical IES emitter¶
Description¶
The spherical IES emitter uses IES data and for any point on a sphere geometry, derives a planar source model, so that the full sphere has the same radiance distribution as the IES data. It is suited for any kind of IES source, and requires to be applied on a sphere geometry.
As IES files contain only luminous intensity information and no spectral data, a base spectrum must be specified. It is then normalized to keep the IES values correct.
IES values apply to a whole light source, while Ocean works with surfaces and light emitted by unit area.
The actual lumen output will depend on flux mode:
In “Per Instance” mode, IES values are mapped to object instances. If a 1000 lumen IES source is applied to two instances of a luminaire geometry, they will emit 1000 lumen each. But if a single geometry models two luminaires, and is instanced once, the luminaires will share the 1000 lumen flux, and will emit 500 lumen each if they are identical.
In “Per m2” mode, IES values are mapped to every square meter of geometry. If a 1000 lumen IES source is applied to a 0.20m2 geometry, the resulting light output will be 200 lumen.
Note
Using this feature requires a Lighting or Advanced Edition license
Children Nodes¶
The base emission spectrum |
|
The angular light distribution function |
Parameters¶
name |
type |
description |
---|---|---|
forward |
vec3 |
Orients the IES light source main axis to this direction in world space |
right |
vec3 |
Rotates the IES light source around its axis to set its right pointing at this direction in world space. Should be orthogonal to forward |
flux |
list |
Sets the flux mode (“instance” or “squaremeter”) |
multiplier |
real |
Multiplies all IES values by this factor |
Ocean XML 6.0 example¶
<emitter name="emitter" type="spherical_ies" forward="0 -1 0" right="0 0 -1" flux="instance">
<spectrum type="tabulated" name="base">
3e-07 0 4e-07 0 5e-07 1.2e+08 6e-07 2.4e+08 7e-07 2.9e+08
</spectrum>
<text name="iesdata">
[Truncated IES data...]
</text>
</emitter>