Creating an Environment Source

An Environment Source generates light from an hdr image (HDRI) according to the RGB components of each pixel.

Tip: Where to download a .hdr file:

To create an Environment Source:

From the Light Simulation tab, click Ambient and click Environment .
In the 3D view:
- click a line (normal to the ground) to set the Zenith direction.
- click a line corresponding to the X axis to set the North direction.
- or click and select a coordinate system to autofill the Axis System.
If you need to adjust the axes' orientation, use Reverse direction.

Note: If you define manually one axis only, the other axis is automatically (and randomly) calculated by Speos in the 3D view. However, the other axis in the Definition panel may not correspond to the axis in the 3D view. Please refer to the axis in the 3D view.
In Luminance, define the pixels' luminance.

Note: The luminance set here is the floating point representation of the reference white color (1,1,1). The luminance of each pixel is calculated according to its RGB components and the reference pixel. The luminance usually varies between 1000 and 20000 ^cd/m2.
In Image file, click Browse to load an image or HDRI file.

Note: HDRIs have relative luminance values. If you set the luminance to 1000 cd/m², all the (1,1,1) pixels will have 1000 cd/m². The other colors are defined relatively to this one.
In Color Space, from the Type drop-down list, select which color space based model to use according to your needs and to the image file's own color space:
- Select sRGB to use the standard and most commonly used RGB based model.
- Select Adobe RGB to use a larger gamut.
- Select User Defined RGB to manually define the white point of the standard illuminant. From the White Point Type drop-down list:
  - Select D65 to use a standard daylight illuminant that provides accurate color perception and evaluation.
  - Select D50 to use a natural, horizon light.
  - Select C to use an average daylight illuminant.
  - Select E to use an illuminant that gives equal weight to all wavelengths.
  - Select User defined if you want to edit the x and y coordinates of the white point (the reference point of the model).
    
    Note: For more information about color models or white points of standard illuminants, see Colorimetric illuminants.
If you selected User Defined RGB from the Color Space drop-down list, load a spectrum file for each primary color.

If you want to modify or create a .spectrum file, click Open file to open the Spectrum Editor.

Tip: You can also download spectrum files from the Ansys Optical Library.
If you selected an HDR image and want to define a ground plane, click a point in the 3D view to determine the ground origin and type the Height of the environment shooting.

The HDR image is displayed on the ground plane. Thus, the ground plane acts like a textured geometry that can reflect/absorb light from other sources.

Tip: To maintain the scale, use the real height of the environment shooting. If you do not have that information, the standard height is 1m.

The Environment Source is created and appears in the Simulation panel. The luminance is calculated according to the reference pixel. If a ground plane is defined, it is taken into account for simulation.



Without a ground plane	With a ground plane