form•Z | Lighting | Environment Light

Owned by ben (Unlicensed)
Last updated: 16 Jul, 2012 by Mihai Iliuta (Unlicensed)Version comment
6 min read

 

Environment Light Types

The Environment light types are dedicated to the accurate simulation of global and atmospheric light.

Multiple Physical Sky and Sky Dome lights may exist in a project simultaneously, allowing for the setup of various shots at different times of day or under different atmospheric conditions. However, only one of these light types can be active (or “shining”) at a time.

Likewise, multiple IBL lights may exist at once, but only one may be active (“shining”) at a time. If a Physical Sky light or Sky Dome is also active, the sky light will be used for any unused channels in the IBL. For example, if an IBL and a Physical Sky are both active, and the IBL uses only the background channel, the illumination, reflection, and refraction channels will be provided by the Physical Sky.

 

Physical Sky

Top: Sun Disabled indicator icon;  Bottom: Sun Enabled indicator icon

Maxwell Render has a sophisticated atmosphere model that reproduces the skylight conditions at a given location locations at any date and time of day. The atmospheric parameters allow users to customize the appearance of the sky and the resulting light in the scene. For more information, see Physical Sky.

Intensity Tab
  • Open: Select a Sky Preset from disk.
  • Save: Save the current sky from disk, for use as a preset later.
  • Sun: Enables / disables direct sunlight. This parameter is linked to the lights ‘Shadows’ button in the Lights palette. If disabled, only ambient sky light will illuminate the scene.
  • Power: Specifies the light output of the sun as a multiplier, where a value of 1 is equivalent to the the Earth’s sun. (i.e., A value of 2 would be twice that of the Earth’s sun, while a value of 0.5 would be half that of the Earth’s sun.)
  • Temperature: Specifies the temperature of the sun’s spectral radiation, in degrees kelvin. The default value of 5777ºK is the most common value measured outside the Earth’s atmosphere.
  • Planet Reflectance: Specifies the percentage of light reflected from the planet surface back into the atmosphere. Changing this value will brighten / darken the overall sky and scene illumination with lower values giving a darker result. Common values are 26-32%.
Location Tab

  • Sun Location:
    • Origin/COI: The sun will be located according to the origin and COI parameters, and can be adjusted by moving the sun indicator in the 3D modeling space.
    • Altitude/Azimuth: The sun will be located by sun altitude, azimuth, and site rotation. Site rotation allows you to change the site north direction without rotating the model itself. In this mode, the Physical Sky will be automatically locked to avoid moving it within the modeling space.
    • Site/Time: The sun will be located by longitude, latitude, day, time, GMT offset, and site rotation. Site rotation allows you to change the site north direction without rotating the model itself. In this mode, the Physical Sky will be automatically locked to avoid moving it within the modeling space.
Parameters Tab
  • Ozone, Water, Turbidity Coefficient, Wavelength Exponent, Reflectance, Scattering Asymmetry: These parameters affect the color distribution throughout the sky. For a detailed discussion, see Physical Sky.
  • Length: Controls the length of the Sky Dome indicator in the 3D modeling viewport.

 

Sky Dome

Provides a uniform color or gradient dome to illuminate the scene. Sky Dome is appropriate for interior scenes with minimum exterior light penetration, and renders faster than Physical Sky.

Intensity Tab
  • Intensity: Specifies the intensity of the Sky Dome in cd/m2.
  • Zenith: Click to specify the color at the zenith.
  • Horizon: Click to specify the color at the horizon.
  • Midpoint: The midpoint of the color gradient between the horizon (at 0°) and zenith (at 90°).
  • Sun, Temperature, Planet Reflectance: These options are identical to those in Physical Sky (see above).
Location Tab

These options function identically to those in Physical Sky (see above).

Parameters Tab
  • Length: Controls the length of the Sky Dome indicator in the 3D modeling viewport.

 

IBL (Image Based Lighting)

Image Based Lighting allows you to light your scene by applying a high-dynamic range image (HDRI) to a virtual sphere that encompasses your scene. IBL may be used to accurately reproduce the quality of light present at a real location.

HDRI, MXI and EXR image formats are supported. The images used for IBL should be in the Latitude/ Longitude format (the width should be twice the height). Images in “strobes” or “cross” formats will not work correctly.

There are four channels that may be mapped: background, illumination, reflection, and refraction. The same image can be mapped to all channels, or different images can be mapped to each channel.

It is not necessary to use all channels. If a channel is disabled, the active Sky Dome or Physical Sky will be used for that channel instead (or, if no sky is active, the channel will be unused).

Intensity Tab
  • Mode:
    • Simple: In simple mode, the same image is used for all four channels, and a single set of controls for rotation and scale affects all the channels  equally. The channels can be enabled and disabled individually, however, and their relative intensities can be independently adjusted.
    • Detailed: In detailed mode, each channel is completely independent from the others, and can be mapped with its own image, have unique rotation and scale parameters, etc.
  • Open: Select HDRI from disk.
  • Delete: Remove link to HDRI.
  • View: View HDRI preview.
  • Background: When checked, the background channel will be enabled. This channel adds an IBL map that provides a background image for the scene. This channel does not provide any scene illumination or reflections.

  • Reflection: Adds an IBL map for reflections on objects within the scene. This map will be visible in any objects that have a reflective material applied to them.

  • Refraction: Adds an IBL map for refractions within objects in the scene. This map will be visible through objects that are transparent and refractive, ie. which have ND higher than 1).

  • Illumination: Adds an IBL map for illuminating the scene. This map will be used to illuminate the scene.

  • Intensity: Adjust the intensity of the map to increase or decrease its contribution to scene illumination, reflections, or refractions.
  • Rotation Azimuth, Rotation Altitude: Rotates the spherical environment. (In degrees.)
  • Scale Azimuth, Scale Altitude: Scales the current map. (Multiplier)
  • Mapping:
    • Spherical: The background will be mapped to the entire spherical environment dome.
    • Screen: The image will mapped to the width and height of the output image. This option is only available for the background channel in Detailed mode; in Simple mode, the background mapping with be spherical. The other three channels are mapped spherically in either mode.