Cone emitter¶
This emitter has a cone angular distribution
It is defined by:
A base light emission spectrum, setting dependence of radiance to wavelength
A filter shader modulating the radiance across the geometry surface
A scalar shader defining the tangent of the cone angular radius
Luminous values may be normalized using the metric and quantity parameters as follows:
Custom metric : the emission properties are normalized to match the quantity defined by value and quantity
Base spectrum : base child defines the light quantity, as a spectral flux per instance or a spectral emittance per unit area, depending on the quantity parameter. multipler is unitless
It should be noted that all normalization occurs before the posmod function is applied.
Note
This emitter was previously made using a Generic Emitter associated to a Cone Distribution before Ocean 2017 R5
Understanding metric¶
The actual physical emission values are derived from metric and quantity parameters
Metric |
Quantity |
Value |
Unit |
---|---|---|---|
Base spectrum |
Spectral flux (per instance) |
base * multiplier |
W/m |
Base spectrum |
Spectral emittance |
base * multiplier |
W/m3 |
Custom |
Luminous flux (per instance) |
value |
lumen |
Custom |
Luminous emittance |
value |
lumen/m2 |
Custom |
Energy flux (per instance) |
value |
W |
Custom |
Energy emittance |
value |
W/m2 |
For instance, in Base Spectrum Spectral Emittance mode, the base spectrum child values are multiplied by multiplier, and this sets the source emittance, in watts per wavelength unit (meters) per unit area (m²).
In Custom Luminous Flux mode, the value sets the lumen value per instance.
Children nodes¶
The base emission spectrum |
|
The spectral position modulation function |
|
The tangent of the cone angular radius |
Parameters¶
name |
type |
description |
---|---|---|
metric |
list |
Sets the metric mode (Custom or Base spectrum) |
quantity |
list |
Sets the quantity or unit of the metric |
value/multiplier |
real |
Defines the value (Custom metric) or the multiplier (Base spectrum metric) |
Ocean XML 6.1 example¶
<emitter type="cone" name="emitter" metric="custom" quantity="lumflux" value="50">
<spectrum type="blackbody" name="base" temp="3000" gain="1e-06"/>
<filtershader type="constant" name="posmod" value="1"/>
<scalarshader type="uniform" name="tanangle" value="2"/>
</emitter>