Basic Lighting

Tutorial 2 in the Basics of Twilight Render V2 Series

Accurate lighting is a critical component of a successful render, especially when showing indoor spaces.  Creative lighting can add dramatic effect or draw focus to an important detail.  Twilight Render provides an easy-to-use lighting tool to place lights within your scene, as well as a complete editor to adjust all the features of your lights.  In this tutorial, we will step through the basics of inserting a light, editing it's properties, and changing it's type.



The light placement tool allows you to insert a light in your scene using SketchUp's standard placement tools.  The tool works using 3 mouse clicks: anchor, position, and target.

  1. Click the Twilight Render Light Tool button in the toolbar.
  2. The editor window will open.  You may need to move it out of the way for the moment.
  3. Using the Light Tool, click in your scene where you want the light to be anchored.  This is not the final position of the light.  This is a reference point, such as a wall or ceiling near where your light will be placed.  This is the first of 3 clicks.
  4. Next, click where you want the light to be positioned.  You can use SketchUp's built in inferencing to constrain the position along a line, axis, or face.  This is the second of 3 clicks.
  5. Finally, click where you want the light to point, or target.  If the light is an Omni or Point light, the target is not important.  However, for all other types, Spot, Projector, and IES, the light will point towards your target selection.  This is the last of 3 clicks.
  6. After your final click, the new light will be created in your scene and the light editor will update to edit your newly created light.

pointlight size

 The Twilight Render Light Editor allows you to set various properties of your light, like color and size.  The realtime preview in the editor shows the effects of your change.

  1. Color changes the color of the emitted light.
  2. Size sets the radius of your light.  You will notice when you change the radius that the size of the light component in your scene changes to reflect the change in size.  It is important to make sure that your light is not intersecting any other scene geometry!
  3. Power and Efficiency work together to control the amount of light produced.  The Efficiency selector has many predefined light types and the corresponding efficiency percentage.  The amount of light is always Power X Efficiency.
  4. Shadow enables or disables the casting of shadows from this light.  Only biased render presets (Low/Low+ through High/High+) are affected by this; unbiased presets will always cast shadows.
  5. Soft Shadow enables or disables blurry shadows.  How blurry, or soft, the shadow is depends on the light Size.

Twilight Render supports several different types of lights, including Omni lights, which emit light equally in all directions, Spot lights, which emit light in a cone, Projector lights, which emit light in a rectangular pyramid, and IES lights, which emit light in complex patterns.

Spot lights have two main characteristics, Hot Spot and Fall Off.

  1. You can convert a light to a Spot light (or any other type) by selecting from the Type list.
  2. The Fall Off angle is the angle that defines the outer cone; outside of it, the light stops completely.
  3. The Hot Spot angle defines the inner cone; inside of it, the light is at it's maximum brightness.
  4. Between the Hot Spot angle and the Fall Off angle, the light gradually fades from maximum brightness to blackness.
ies light sm

IES Lights use data from files to create complex lighting patterns.  Many IES files are created from measurements of real-world lights.  Many manufacturers provide IES data for their lighting fixtures and can be downloaded from their websites.

  1. You can convert a light to an IES light (or any other type) by selecting from the Type list.
  2. The IES File specifies the data to use to create the light.  Browse to, and select your chosen IES file.
  3. The SketchUp component representing the IES light will be display geometry to represent the light shape.
  4. The Light Editor provides a Wall Sconce preview scene that shows the pattern of the light against a wall and desk surface
  5. Because IES lights represent actual lighting measurements, Power should always be set to 1 and Efficiency to 100%.
light shadow

Accurate shadows can add a great deal of realism to any rendered scene.  The characteristics of each light, especially the light size, dictate the appearance of the shadows.

  1. Shadows can be enabled or disabled by checking the Shadow box.  However this only affects biased render methods (Low/Low+ through High/High+).  Unbiased methods always cast shadows.
  2. Soft Shadow enables shadows that fade or blur along the edges, providing a more realistic appearance.
  3. A small light radius creates sharper shadows.
  4. A larger light radius creates more blurry shadows.



Saturday, June 15, 2024

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