Perez sky environment

Description

../../../_images/perezsky.jpg

Scene lit by a Perez sky environment

Environment The Perez sky environment corresponds to the diffuse sky model defined in:

  1. Perez,R. Seals and J. Michalsky, An all-weather model for sky luminance distribution, Solar Energy 50 235-245 (1993)

This environment only includes diffuse light. In conditions where the sun is apparent, its contribution should be added by using a disc or direct sun and an additive environment.

The luminance distribution is defined by five parameters a, guilabel:b, guilabel:c, guilabel:d and guilabel:e. The integrated diffuse horizontal irradiance or illuminance (DHI) is normalized by the corresponding dhi and dhitype parameters.

By default, zenith is oriented towards (0,0,1). The environment orientation can be adjusted by modifying the zenith parameter.

Note

Using this feature requires an Lighting Edition license

Children Nodes

Spectrum base

The environment spectral distribution

Parameters

name

type

description

sunpos

vec3

The sun direction

zenith

vec3

Zenith direction, allows for instance switching between Z-top and Y-top conventions

dhitype

list

The type of normalization corresponding to the dhi parameter.

dhi

real

The Direct Normal Illuminance/Irradiance value, depending on dhitype

a

real

The a parameter of the model

b

real

The b parameter of the model

c

real

The c parameter of the model

d

real

The d parameter of the model

e

real

The e parameter of the model

Ocean XML 3.0 example

<environment type="perezsky" name="perezsky">
     <prm sunpos="-0.4629 -0.8201 0.3365"/>
     <prm zenith="0 0 1"/>
     <prm dhitype="illuminance" dhi="2000"/>
     <prm a="-0.855285" b="-0.385745" c="12.9569" d="-3.45105" e="0.231486"/>
             <spectrum type="preset" name="base" value="D65" gain="1"/>
</environment>