Envmap environment¶
Description¶
The envmap environment uses a spherical image file for controlling the environment lighting. It uses equirectangular projection, where the horizontal axis is longitude and the vertical axis latitude.
The emission spectrum of the image white point (corresponding to RGB=1,1,1) is defined by a spectrum child element.
By default, the top of the image is oriented towards (0,0,1), and its center to (1,0,0). The envmap orientation can be adjusted by modifying the up ` and :guilabel:`front parameters.
The intensity of the envmap is, by default, equal to the image values, multiplied by the base spectrum. However, it is possible to override the intensity by setting the normalize and value parameters. The normalize parameter can have the following values:
Disabled (disabled) : light intensities are directly proportional to the image values and to the base spectrum. value is ignored.
Horizontal illuminance (hzillum) : value sets the horizontal illuminance in lux.
Average luminance (avglum) : value sets the average luminance over all the sphere in cd/m².
Horizontal power (hzpower) : value sets the horizontal energy power in W/m².
Average radiance (avgrad) : value sets the horizontal energy power in W·sr/m².
Children Nodes¶
The white point base spectrum emitted by RGB=1,1,1 image pixel values |
|
The equirectangular envmap image |
Parameters¶
name |
type |
description |
---|---|---|
up |
vec3 |
The direction where the top of the image (zenith) is oriented in space. Should be orthogonal to front |
front |
vec3 |
The direction where the center of the image is oriented in space. Should be orthogonal to up |
normalize |
list |
The intensity normalization mode (see above) |
value |
real |
The value corresponding to the normalize mode |
Ocean XML 4.0 example¶
<environment type="envmap" name="studio">
<prm up="0 0 1" front="-1 0 0"/>
<prm normalize="hzillum" value="500"/>
<spectrum type="blackbody" name="base" temp="6500" gain="1e-05"/>
<image type="" name="image" path="photo-studio.exr"/>
</environment>