CPSC 424, Computer Graphics, Spring 2010
Lab 10: Blender's Sequencer

One of the final projects for this course is an animation made in Blender. You will want to do some modeling and most likely some "scenery" for the models to move in. You will want to create and save a number of animations, using your models. You might want to include some camera animations. You might want to film the same scene from different viewpoints. You will probably want to create some titles with animated text. All the animations should be saved at the same size; not too small -- maybe 640 by 480 or 800 by 600. Once you have all the individual animations, you will need to combine them into a single animation using the Blender sequencer.

The lab on April 6 will give you a chance to get familiar with using the sequencer. This will probably not take the entire lab. You can use any remaining time to work on your final project.

There is nothing to turn in for this lab. I will give you a few points for showing up and doing the exercises.

Setup for Using the Sequencer

Follow this link to see a screen shot of the sequencer in use. You can also look at the 25-second 9.5MB animation file that was produced.

In the center of the screen is the Sequence Window. This is your main work area. It contains a colored strip for each item that has been added to the sequence. The bottom of the Sequence Window shows time in seconds. A vertical green bar marks the current frame. You can drag this line -- or simply left-click in the window -- to change the frame number. You can zoom in and out in the Sequence Window by using the scroll wheel on the mouse or by using the Keypad + and - keys. You can use the middle mouse button to drag the entire content of the Sequence Window around.

Just below the Sequence Window is a very small timeline window. This window is labeled with the time given as a frame number, and it has playback buttons that you can use to play a preview of the sequenced animation.

On the bottom is the Buttons Window. The Scene Buttons (F10) are selected. Note that the "Do Sequence" option has been turned on, just below the big "ANIM" button. To render the animation from the sequencer, you must turn on the "Do Sequence" button. Aside from that, rendering a sequence animation is the same as rendering any animation. Set the size that you want, set the format to AVI Jpeg, set the starting and ending frame, and set the output location before you render. Click "ANIM" to create the animation.

Exercise 1: Image with Titles

Get a copy of the file lab10-exercise1.blend, either from /classes/s10/cs424/lab10-files or by downloading it from this link. This blender file defines an animation of some text moving across the screen. For the first exercise, you will see how to render this animation on top of an image, along with some other effects.

The animation that you will create should have its own scene. Use the Scene menu at the top of the Blender window to create a new, empty scene. Once you're in that scene, use the Screen menu to go to the "Sequencer" screen.

To add a new item to the sequence, you can use the "Add" menu at the bottom of the Sequence Window. Alternatively, you can hit the space bar while the mouse is over the Sequence Window.

Start by adding an image. The command is listed as "Images" or "Image Sequence", but you can use it to add a single image. You can select an image of your own, or use one from /classes/s10/cs424/lab10-files. Once you've selected the image, you will see a bar or "strip" in the sequence representing the image. It will be in grab mode. Use the mouse to put it where you want it, and click the left mouse button (or press return) to end. Position the image strip so that the left end of the strip is at frame 1. While the strip is in grab mode, the start and end frames are shown at the end of the strip, to help you position it exactly.

An image strip lasts, by default, for 50 frames. In this case, I want the image to stay around for 110 frames. Select just the right end of the image strip, by right-clicking it, use the "g" key to put it into grab mode, and move the right end of the strip to frame number 110.

When the animation starts, I would like to see a fade from black to the image over the course of the first 10 frames. Add a "Color Generator" to the sequence, and position it to start at frame 1. (You can find "Color Generator" in the "Effects" submenu of the "Add" menu, but if you use the space bar to call up the menu, you will find it on the top level of the menu.) Move the right end of the Color Generator to frame 10.

The color, by default, is gray. I want to change the color to black. To change the setting, you need to go to the Sequencer Buttons: Click the second icon in the group of four shown here. Right-click the color generator to select it. You should see an "Effect" pane in the Buttons window. For a color generator, the only Effect control is a color patch. Click the gray patch and select black from the color chooser that pops up.

Now, we want to arrange the "cross" from the black color generator strip to the image strip. A "Cross" is an example of an effect that acts on two strips. Select the color strip, then shift-right-click the image strip to add it to the selection. Use the "Add" / "Effects" / "Cross" command to add a cross to the sequence. The Cross strip must be positioned above the color generator and image strips; the topmost strip controls what is actually rendered. The order in which you selected the strips is important: The crossover starts with the first item selected and ends with the second item. You can drag the vertical green line through the first 10 frames to see what the cross looks like.

Next, add the text animation to the sequence. This animation is in another scene in the Blender file. To add this scene to the sequence, use the "Scene" option in the "Add" menu. You will have to select the scene that you want to add -- the one you want is just named "Scene." Position the scene strip starting at frame 11. It will end in frame 110. The scene is 100 frames long because the start and end frames for that scene were set to 1 and 100.

Between frames 10 and 110, there are two strips, the image strip and the scene strip. You have to say how to combine these; otherwise, just the top one will be rendered. Combine them with an "Alpha Under" effect: Select the scene strip, add the image strip to the selection, and add an "Alpha Under" effect. The image will be shown under the scene, and the scene is considered to be transparent where there is no geometry, that is, where the background shows. That is, you should see the text rendered on top of the image. (If you don't, maybe you selected the strips in the wrong order?)

Finally, I'd like the movie to fade to black during the last ten frames. Add another black color generator, extending from frame 100 to 110, or simply duplicate the one that you already have using Shift-D. And add a Cross from the new color strip to the Alpha Under strip. The sequence editor at this point should look something like this, except that your strips don't have to be in the same vertical positions:

It's time to render the animation. Go back to the Scene buttons. Set the output format to "AVI Jpeg". Set the ending frame to 110. Set the output location. And hit the ANIM button! SHOW ME YOUR ANIMATION.

Note: It's not usually a good idea to use a Scene strip in the sequencer, since every frame of the scene has to be rendered anew every time it's needed. It's a better idea to render the scene to get an animation file, and add that to the sequencer. I used a scene in this exercise only so that I could use the Alpha Under effect to add the text to an image. If I had saved the scene as an animation, the background would not have been transparent, and Alpha Under wouldn't have worked. By the way, you can add text over an animation just as easily as we added the text in this example over a still image, by using a movie strip instead of an image strip.

Exercise 2: Combining Animations

Now that you know the basics of using the sequencer, you can use it to combine several animations. To add an animation file to the sequencer, use the "Movie" command in the "Add" menu. Note that if you change the size of a movie strip, you are not speeding up or slowing down the animation. You are merely cutting off frames or adding new, blank frames. This can be useful if you want to insert just part of an animation into the sequence.

Combine at least four animations into a longer animation. You can use your own animations or the ones in /classes/s10/cs424/lab10-files. Some pairs of animations should overlap, and you should add transition effects between the pairs. Try "Gamma Cross", which is like "Cross" but does some color corrections that should make it look better. And try "Wipe", (In the "Effects" of the Sequencer Buttons, you can select from several types of wipe, such as "Double Wipe" and "Cross Wipe." Try them all! And try adding some blur.)

To finish the lab, render your combined animation, and SHOW IT TO ME.

David Eck for CPSC 424