Lighting Analysis

This feature enables architects and designers to visualise the effects of light on and in their designs. It can be used to simulate the impact of heat caused by the sun's interaction with a building, or to identify dark spots within a proposed design.

Using Lighting Analysis

Lighting Analysis is enabled and controlled from the Analysis tab, which can be accessed by selecting Rendering > Render Setup… from the 3ds Max menu bar. Settings on this tab affect both Production Rendering Mode and ActiveShade renders. If you wish to view the Additional Lighting Elements (see below) then consider using the Iray+ Frame Buffer.

Lighting Analysis

Use the controls on the Lighting Analysis rollout to specify and configure the behavior of Lighting Analysis:

Enable: toggles Lighting Analysis on or off. Two modes are supported.

• Illuminance: shows the total luminous flux incident on a surface, per unit area. Measured in Lux (lx) or foot-candles (fc).
• Luminance: shows the luminous intensity per unit area of light travelling in a given direction in a solid angle. Measured in Candela per square meter (cd/m²).

Additional Lighting Elements: lets you specify additional Render Elements, which can be displayed in the Iray+ Frame Buffer and which will be saved out in Production Rendering Mode.

• Direct Light: shows the direct illuminance or luminance (depending on selected mode) from light sources only, ignoring reflected light.
• Indirect Light: shows the illuminance or luminance (depending on selected mode) from reflected light only, ignoring direct light sources.

Labels

Real-time labels let you view lighting information at a point or within an area on the Frame Buffer.

Three modes are supported.

• Custom: lets you choose label locations interactively.

  Left mouse button: click and drag to view average, minimum, and maximum values in the selected area.	Right mouse button: click to view a value at a single point. Hold down the button while dragging to update the value for each new pixel that you visit.

  • Persist: when enabled, labels remain on screen after you release the mouse buttons.
  • Clear: removes any labels displayed on the Frame Buffer.
• Detailed: lets you inspect the calculated and mapped RGB values for the illuminance or luminance (depending on selected mode) at any point on the Frame Buffer. Click the Right mouse button to view these details in the Pixel Data window:
  

  Hold down the Right mouse button while dragging to update the data shown for each new pixel that you visit.

• Grid: lets you overlay a grid of lighting information onto the Frame Buffer.
  
  • Vertical Divisions: controls the vertical density of grid points.
  • Horizontal Divisions: controls the horizontal density of grid points.
  • Generate Grid: displays a grid of lighting values on the Frame Buffer at the chosen density.
  • Clear: removes the grid of lighting values from the Frame Buffer.
  
  
  ✱  Note: you can adjust the Color and Size of the font to optimize the grid's legibility.
  
  
  ✱  Note: click the Left mouse button to restrict the grid to the currently selected geometry (or to extend the selection). This operation is performed in screen space and will not account for perspective. Click the Right mouse button to remove the restriction and display the full grid.

Illuminance

When Illuminance is enabled on the Lighting Analysis rollout, use the controls on the Illuminance rollout to specify how illuminance should be mapped to false color:

Color Mapping: controls the mapping of illuminance values in the scene to the false color display and the scale of the color chart.

• Units: use the dropdown to select the illuminance display units:
  • Lux (lx)
  • fc (Foot-candles)
• Auto Range: maps the entire range of scene illuminance values to false color.
• Custom Range: maps only illuminance values in the specified custom range to false color:
  • Min: sets a lower limit for the Custom Range. Lower values will be clamped to blue.
  • Max: sets an upper limit for the Custom Range. Higher values will be clamped to red.

Luminance

When Luminance is enabled on the Lighting Analysis rollout, use the controls on the Luminance rollout to specify how luminance should be mapped to false color:

Color Mapping: controls the mapping of luminance values in the scene to the false color display and the scale of the color chart.

• Auto Range: maps the entire range of scene luminance values to false color.
• Custom Range: maps only luminance values in the specified custom range to false color:
  • Min: sets a lower limit for the Custom Range. Lower values will be clamped to blue.
  • Max: sets an upper limit for the Custom Range. Higher values will be clamped to red.

Lighting Analysis Toolbar

When using the Iray+ Frame Buffer (under either Production Rendering Mode or ActiveShade Mode), an additional toolbar will be displayed below the window when performing lighting analysis:

This toolbar displays a color chart showing how the false color scale maps to either the Auto or Custom illuminance/luminance range, as well as the absolute minimum and maximum illuminance/luminance values in the view. When using the default 3ds Max frame buffer, a similar toolbar is displayed for the ActiveShade Mode window, but not for the Production Rendering Mode window.

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