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How to Create and Use Physical Lights in KeyShot

by Will Gibbons | Dec 21, 2016 | Tips | 1 Comment

In KeyShot, there are two ways to light your scene. HDRIs are the default method, but physical lights can be used as well. A combination of both HDRI and physical lighting works well too. To add a physical light, simply drag and drop a light material from the KeyShot Library to a piece of geometry in your scene. There are four light material types in KeyShot and each behave differently, providing a wide array of uses in lighting your scene. Understanding the different light material types in KeyShot will allow you to choose the best light for your particular scene.

KeyShot Light Material Types

  1. Area Light Diffuse
  2. Point Light Diffuse
  3. Point Light IES Profile
  4. Emissive

Light Material Type Properties

Area Light Diffuse

  • Light is emitted from each surface of the geometry it’s applied to
  • The geometry remains visible
  • Use for soft lighting and shadows
  • Area Lights emit light normal to each triangle on a surface (see tessellation if not familiar with triangles)
  • Best used for local illumination
  • Only Apply to Front of Geometry or back of geometry as needed, avoid enabling both checkboxes to increase efficiency
  • Change Watt, Lumen or Lux to adjust brightness

Point Light Diffuse

  • Light is emitted from a single point located at the center of the geometry it’s applied to
  • The geometry disappears when a point light material is applied
  • Use for sharper highlights and shadows
  • Point Lights are omnidirectional, so they will emit light in every direction from a single point
  • Best used for illuminating a whole scene (imagine a mini-sun)
  • Change Watt or Lumen to adjust brightness

Point Light IES Profile

  • Light is emitted from a single point in the center of the geometry it’s applied to therefore, very efficient
  • The geometry disappears and is replaced with an IES cage
  • IES Profiles are pre-made, standard light files with real-world color, shape and intensity information
  • IES Profiles are directional, so they can be pointed by rotating the geometry they’re applied to
  • Best used for mimicking manufactured light bulbs
  • Change Multiplier to adjust brightness

Emissive Light

  • Not suitable for illuminating a scene
  • Best for low-intensity lights
  • Light is emitted from each surface of the geometry it’s applied to. (Similar to Area Light Diffuse)
  • Used for light-emitting materials such as bioluminescent materials, illuminated displays and small lights (phones, tablets, computers, glow-in-the-dark, televisions, LEDs)
  • Emissive Lights emit light normal to each triangle on a surface
  • Can be textured
  • Only Apply to Front of Geometry or back of geometry as needed, avoid enabling both checkboxes to increase efficiency
  • Can be hidden from camera
  • Change Intensity to adjust brightness

Units

Scene and model units are important to consider when using physical lights. It's best to use models that are built to scale. Further, you should refrain from scaling models after importing into KeyShot. When improper units are used, lights may appear too bright or not bright enough. Another consideration is distance. The further a physical light is from its target, the darker the target will be.

Watt

  • A measure of power, not brightness
  • An incandescent bulb that consumes 100 Watts emits about 1,600 Lumens

Lumen

  • A measure of emitted light
  • An LED light that emits 1,600 Lumens will consume about 18 Watts

Lux

  • Lux, or Lumens per square meter, is a measure of light intensity that takes into account surface area
  • A one-square meter surface emitting 1,000 Lux will appear brighter than a two-square meter surface emitting the same 1,000 Lux. The overall brightness is decreased as the light is spread across a larger surface.

Intensity

  • IES Profiles already contain a specific brightness setting, which KeyShot represents with an intensity value of 1
  • To increase or decrease brightness beyond the actual (in-real-life) brightness, adjust the intensity value

Multiplier

  • IES Profiles already contain a very specific brightness setting, which KeyShot represents with a multiplier value of 1
  • To increase or decrease the brightness beyond the actual (in-real-life) brightness, adjust the multiplier value

Best Practices for Using Physical Lights

KeyShot allows you to go beyond lighting with an HDRI and use physical lights to light more accurately and realistically. Be sure to remember these key points to ensure good results.

  • Global Illumination must be enabled to see indirect light on all surfaces
  • Ground Illumination must be enabled to see light on the ground if no ground plane is present
  • Do not use Emissive materials to illuminate a scene
  • Use IES profiles to simulate man-made lights
  • Point lights are highly efficient (keep KeyShot running faster)
  • Area lights efficiency depends on geometry it’s applied to
  • Make sure models are made to scale with real-world units
  • Use Lumens or Lux for brightness settings
  • Avoid applying light to both front and back of geometry (Area & Emissive lights only)

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