Slide-based tours have start and end positions; WorldWide Telescope (WWT) smoothly moves between these positions. However, the Timeline Editor gives you greater control over changing the views, location, and appearance of objects in a tour. Each slide of a tour can have its own timeline control.
Important: Tours containing timelines can only be played back on WWT 5.0 or later. When you first add a timeline, you will see a warning to this effect.
Create a tour using the Timeline Editor
To create a new tour that uses the TimeLine Editor, do the following:
- Create a new tour: select Guided Tours and then click Create a New Tour...
- From the Look At drop-down in lower left of the screen, make a selection and the orient initial view for your Tour.
- Create an initial slide: click Add New Slide at upper left of screen.
- Right-click the thumbnail of this slide and select Create Timeline. This will display a timeline at the bottom of screen.
In the image of the timeline below, the buttons outlined in green allow you to adjust the size of the window as well as unpin it from the main window.
The WWT timeline
The Timeline Editor shows objects and settings on the left. Initially, you will see a single element on the left called Camera. Click the "+" symbol to the left of Camera to display a list of attributes you can control.
The blue transport controls in the lower left allow you jump to the beginning or end of the timeline, play the tour forward or backward, and pause the tour. You can also navigate through your timeline by dragging the yellow triangle (the “time scrubber”), which points to the current location in the timeline.
The time is displayed across the top of the timeline in MM:SS. Each second is divided into 30 frames per second giving you precise control up to 1/30 second. To change your view of the timeline, hover the mouse over the numeric labels of the timeline and scroll to increase or decrease the scale.
- The Timeline Editor cannot currently control the Look At mode. This must be set once for the entire slide.
- If you change the duration of a slide within an existing timeline, a dialog box appear, asking you if you want to trim/extend or scale the timeline.
Example: Sky & Solar System Timeline
To demonstrate the capabilities of the Timeline Editor, we will use an example tour, Sky & Solar System Timeline.
- Download Sky and Solar System Timeline.wtt
- Open WorldWide Telescope
- Click Explore and select Open, and then Tour
- Navigate to the Sky & Solar System Timeline.wtt file on your computer and click Open
This opens the example tour. You should now see the Sky & Solar System tour the top menu bar of WWT.
- Right-click the first slide in the tour and select Show Timeline.
You can right-click and select Add to Timeline many of the objects in the Layer Manager on the left side of the screen. For some productions, you may need to turn on the constellations at some point and then fade them out at another point. You can add and separately control constellation pictures, figures, boundaries, and labels. In this example, we will add constellation figures and planetary orbits—both with labels.
- In the Layer Manager, under Sky > Overlays > Constellations, make sure that the Constellation Figures checkbox is selected and then right-click and select Add to Timeline. This will create an object called ConstellationFigures in the timeline.
- In the Layer Manager, under Sky > 3d Solar System, make sure that the Planetary Orbits checkbox is selected and then right-click and select Add to Timeline. This will create an object called SolarSystemOrbits in the timeline.
You can also add overlay objects by clicking the Text, Shapes, and Picture buttons in the upper-right of the WWT window. Once you have created the overlay object, right-click it in the main window and select Add to Timeline. For this example, we’ll create two text objects named “Our Solar System” and “The Sky” and put them at the same location. Then we will add them to the timeline.
- Click the Text button to open the Text Editor
- Type “The Sky” and click Save
- Select the text object in the main window and move it to where you would like it to appear.
- Click the Text button top open the Text Editor again
- Type “Our Solar System” and click Save
- Select the text object in the main window and move it directly over the text “The Sky”. You can use the left, right, up, and down arrows to get text object precisely over the text, “The Sky.”
- Position the time scrubber at 00:00
- Right click The Sky text object and select Add to timeline
- Position the time scrubber at 00:03
- Right click Our Solar System and select Add to timeline
Hint: Sometimes you can’t see the overlay objects because then are stacked up underneath a menu or difficult to find in Full Dome mode. In the Guided Tours drop-down menu, select Show Overlay List. A list of text, shape and image overlays is shown. You can right-click on overlay objects and change the ordering, color, and so forth. You can change the name in the Overlay List by right-clicking and selecting Properties. When using the Timeline Editor, do not select Animation; this is a slide-based method for editing the timeline.
Each object or setting in the timeline can change display attributes at specific times, and WWT will move smoothly between them. These are called keyframes and are represented in the Timeline Editor as small rectangles. Above the list of key objects, there is a button to create keyframes (the Add Key button) and to delete keyframes (the Delete Key button). Initially, a keyframe displays at the beginning of the timeline for every object in the timeline.
The Add Key and Delete Key buttons
Fading in and fading out
We start with a view of the sky with constellations and the text, “The Sky,” then fade out the constellations and fade in planet orbits and the text, “Our Solar System,” and then end with a view of the Solar System. You can move keyframes in time easily, so start by considering the sequence and refine the timing later.
We start by expanding the Timeline Editor by clicking the up arrow at the top of the timeline. First, we adjust the constellation figures to fade out from 00:03 to 00:05.
- In Layer Manager, click the “+” symbols to under Sky to reveal Overlays > Constellations > Constellation Figures.
- Right-click Constellation Figures and select Add to Timeline.
- In the list of key objects to the left of your timeline, click the “+” symbol to expand the list of ConstellationFigures, and click Opacity.
- Move the timeline scrubber to 00:03.
- Click the Add Key button, located above the list of objects on the left of the timeline.
- Move the timeline scrubber to 00:05.
- Make sure Opacity is still highlighted and click the Add Key button.
- Click the first key you made at 00:04 to display the Key Properties pop-up window. If a single key is selected, then the label of the key will be displayed above the field on the upper right. If a key object (such as ConstellationFigures) is not expanded, the Key Properties pop-up will control all attributes. Note that the time field is also shown but you cannot change the time.
Key Properties pop-up window
- Make sure the Opacity is set to 1.
- Edit the Opacity keyframe at time 00:05, and set it 0. Then close the window by typing the X in the upper right.
- Do the same for the Opacity keyframe at time 00:00.
- Edit the Opacity keyframe at time 00:05, and check that it is 1.
- Do the same (steps 1–12) for the Color.Alpha attribute under the object entitled The Sky.
- Run the time scrubber back and forth: you should see the constellations and text The Sky fade out from 00:03 to 00:05.
For the SolarSystemOrbits object, keyframes have been created at 00:03 and 00:05. The Opacity attribute is set to 0 at 00:00 and 00:03 and to 1 at 00:05. The same has been done with the Color.Alpha attribute for the text object Our Solar System. Run the time scrubber over the timeline to see how the solar system and the text “Our Solar System” fade in between 00:03 and 00:05.
Transition Functions: The Timeline Editor can also allow you to select Transition Functions. These affect the way attributes change between one keyframe and another. The transition of input and output values is shown graphically. You can select from the following choices.
- Linear: numbers are linear changes between values.
- Exponential: changes occur more rapidly at the beginning and slow down at the end—similar to EaseIn below.
- EaseIn: changes occur rapidly at the beginning and slowly at the end.
- EaseOut: changes occur more slowly at the beginning and rapidly at the end.
- EaseInOut: changes occur slowly at beginning, rapidly in the middle, and slowly at the end.
- Instant: retains starting value until the very end, where it changes instantly to a new value.
- Custom: allows you to change the curve interactively. Grab the yellow square handle on each end of the curve to manipulate the beginning and ending shape of the transition curve.
Hint: It is good to choose a keyframe such as Camera and try out all the transition functions to get a sense of what they can do.
To set up a Transition Function:
- Open the Camera by pressing the + next to it (it may already be open)
- Click on any of the Camera Key properties by clicking one of the squares in the Timeline Editor
- Select a Transition Function other than Linear and test the effects of this by using the Time scrubber
Manipulating keyframes in Timeline Editor
Besides changing the properties of keyframes, single or multiple keyframes can be selected for deletion, copying, or pasting. Selected keys are shown as yellow. There are three ways to select keyframes:
- Control-A: selects all keys in timeline.
- Control-click: hold down the Ctrl key and click multiple keys to add them to a group.
- Drag rectangle: clicking and dragging a selection rectangle around several keys to select them.
Note: you cannot move the keyframes at time = 00:00, even if they are selected as part of a group.
Moving keys to make a shorter transition
In our last task, we will move the keys from 03:00 to 04:00 to make a shorter transition. To do this,
- Reveal the Timeline Editor and move it to display time 03:00 to 04:00.
- Drag a rectangle over the keys at 03:00. They should all turn from white to yellow.
- Move the selected group of keys to the right and place them at 04:00.
Now play the tour and see how the transition time has changed.