Sunlight and Daylight

Create panel > Systems > Sunlight button and Daylight button

Create menu > Lights > Sunlight System and Daylight

Tab panels > Lights & Cameras tab > Sunlight System

The Sunlight and Daylight systems use light in a system that follows the geographically correct angle and movement of the sun over the earth at a given location. You can choose location, date, time, and compass orientation. You can also animate the date and time. This system is suitable for shadow studies of proposed and existing structures. Latitude, Longitude, North Direction, and Orbital Scale can be animated as well.

Sunlight and Daylight have a similar user interface. The difference is that:

Large view shows compass and light in a viewport. The resulting rendered images are seen above it.

Procedures

To create the sunlight or daylight system:

  1. On the Create panel, click Systems and then click Sunlight or Daylight.

  2. Choose a viewport in which to create a compass rose (the compass direction of your "world"). This should be a Top or Perspective view.

  3. Drag to create the radius of a compass rose (the radius is for display purposes only), and then click and move to set the orbital scale of the directional light over the compass rose. This can be any distance you find convenient, since a directional light produces parallel illumination regardless of where its icon is located.

The default "sun" position is created based on the current time, date, and time zone location set in your computer.

You can then use the system's parameters to adjust these settings. The default location is San Francisco, CA.

Upon creation you have two objects in your scene:

  • The compass rose, which is a helper object that provides the world direction for your sun.

  • The daylight assembly head, which is a child of the compass rose, and is permanently targeted on the center of the compass rose.

    In the Daylight Parameters rollout, the Sunlight list offers options for IES Sun, Skylight, or No Sunlight. The light from the sky can be Clear/Partly Cloudy or Cloudy.

The directional light created by the system is managed by two special controllers: Solar Date and Solar Time. After you create your system, you can access its creation parameters (time and date, location, orbital scale, and location) in the Motion panel for the directional light. The parameters are interrelated, so you can adjust them in any order. Generally, it's easiest to choose a location first, and then adjust the date and time. You can access the parameters for selected sunlight or skylight objects in the Modify panel. The radius of the compass rose is also accessed in the Modify panel, after selecting the compass rose object.

If Date/Time position is selected the Sun and Sky multipliers will be automatically set and animated according to their position. They can only be edited if you used Manual Position override.

Example: To create a shadow study:

  1. Create a Daylight system.

  2. In the Modify panel, In the Daylight Parameters rollout’s Position group, choose Date, Time and Location, then click Setup.

  3. Turn on the Auto Key button.

  4. In the Control Parameters Time group, adjust the Hours spinner to a start time in early morning.

  5. Click the Go To End button.

  6. Animate the end time to late afternoon.

  7. Render to an animation from a Top view, or a view above your scene to get a complete view of your environment, and it’s shadows.

Interface

Daylight Parameters rollout (Daylight system only)

The Daylight Parameters rollout lets you define the daylight assembly head object. You can set the sunlight and skylight behaviors.

This rollout appears on the Modify panel when the light component of the Daylight system is selected.

Sunlight—Select one of three options for sunlight in your scene:

  • IES Sun—Uses an IES Sun object to simulate the sun.

  • Standard—Uses a Target Direct light to simulate the sun.

  • No Sunlight—No sunlight is simulated.

Active—Turns sunlight on and off in the viewport.

Position group

Manual—When on, you can manually adjust the location of the daylight assembly head object in your scene, as well as the intensity value of the sunlight.

Date, Time and Location—When on, uses the geographically correct angle and movement of the sun over the earth at a given location.

Note: When Date, Time And Location is chosen, adjusting the light's intensity has no effect.

Setup—Opens the Motion panel, allowing you to adjust the time, location, and site of your daylight system.

Skylight—Select one of three options for skylight in your scene:

  • IES Sky—Uses an IES Sky object to simulate skylight.

  • Skylight—Uses a Skylight object to simulate skylight.

  • No Skylight—No skylight is simulated.

Active—Turns skylight on and off in the viewport.

Motion panel, Daylight and Sunlight system Control Parameters rollout

This rollout appears on the Create panel, and on the Motion panel when the light component of the Daylight or Sunlight system is selected.

Azimuth/Altitude—Displays the azimuth and altitude of the sun. Azimuth is the compass direction of the sun in degrees (North=0, East=90). Altitude is the height of the sun above the horizon in degrees (Sunrise or Sunset=0).

Time group

Provides spinners for setting the time, date, and time zone.

If the location you select uses Daylight Savings Time, turn on the Daylight Savings toggle. The Sunlight system adjusts the sun's azimuth and altitude accordingly, during the summer months.

Hours/Mins/Secs—Specify the time of day

Month/Day/Year—Specify the date.

Time Zone—Time zones range from -12 to 12. If you're uncertain about a time zone, you can look them up in Window's NT Date > Time Properties dialog, which is available via My Computer > Control Panel > Date > Time. Select the Time Zone tab, and then display the list of world locations and their time zones.

Daylight Savings Time—When on, calculates daylight savings by adjusting azimuth and altitude during the summer months.

Location group

Provides controls for setting the location of your scene in the world.

Get Location—Displays the Geographic Location dialog, which lets you set the latitude and longitude values by selecting a location from a map or a list of cities.

Note: For precise locations, enter exact coordinates using Latitude/Longitude.

Latitude/Longitude—Specify the location based on the latitude and longitude.

Site group

Orbital Scale—Sets the distance of the sun (the directional light) from the compass rose. Because a directional light casts parallel beams, this distance has no effect on the accuracy of the sunlight. However, the light must point toward your model (not away from it), and the light's hotspot and falloff do have an effect. The best way to ensure that the light is set up correctly is to change one viewport to the light's view (for example, Sun 01). Then adjust the light's location using Dolly, and set the hotspot so it illuminates the whole model, with no falloff.

North Direction—Sets the rotational direction of the compass rose in the scene. This is the geographical orientation of the compass rose. By default, north is 0 and points along the positive Y axis of the ground plane. Positive X (East) is 90 degrees. Adjust the North Direction to correspond to your site. Accuracy of the system depends on this correspondence.

Sky Group (Daylight system only)

Clear/Partly Cloudy/Cloudy—Determines how much light is scattered through the sky.


Comments