Movies and Bookmarks in Volocity 4

When I give seminars to my many followers in the scientific world, I like to include a good movie or two to illustrate my talks.  As they say, a picture tells a thousand words – so a movie can really bring my subject to life.  Making movies in Volocity 4 is now easier and gives better results, so here are my tips for getting that Oscar winning performance from your samples!

Movies can now be created by linking together a series of stored positions called bookmarks, to make a free-flowing movie that shows your data to its best advantage.

Bookmarks allow you to store information about the position of the volume and the rendering settings being applied to it.  This is useful because you can make changes to the position and appearance of a volume, then return to a previous position and appearance by clicking on the bookmark.  Bookmarks are great not only for making movies, but also because you can view different data sets with exactly the same settings applied by using the same bookmark to view each data set, so that you can easily compare volume data.

Let’s get started.

In the 3D view, choose "Show Bookmarks" from the 3D menu.  Bookmarks appear in the pane to the right of the window, if there are any there.  The first time you use them, the list will be blank.

To create a new bookmark, position the volume as required (zoom, rotate etc.) and set the Renderer Controls in the Navigation palette to produce the desired appearance.  Select "Add Bookmark" from the 3D menu.  I like to use the keyboard shortcut for this (Ctrl-B on Windows, Apple-B on Mac OS). A thumbnail of the volume will be added to the bookmarks pane.

To use a bookmark, double-click on the thumbnail of the bookmark and the volume will return to the rendering and positional settings stored by the bookmark.  The transition from one appearance to the next is nice and smooth and you see the change take place before your very eyes!  I can step through bookmarks by using "Next Bookmark" or "Previous Bookmark" in the 3D menu.

Once created, I can edit a bookmark by selecting it in the bookmark pane and choosing "Edit Bookmark..." from the 3D menu.

In the dialog I can uncheck any number of states, then that part of the bookmark setting will not be applied to the 3D View when the bookmark is used.

To delete a bookmark, select it in the bookmark pane and use the Delete (Windows) or Backspace (Mac OS) key to remove it.  If you want to compare data sets using the same bookmarks, open both data sets and drag the bookmark from one data set to the bookmark pane of the other data set.  The bookmark thumbnail will update the first time it is used with the new data set.

So now I have a collection of bookmarks that I have set to show my data to best advantage in different orientations, zoom levels, opacities, etc.  I now want to string the bookmarks together to make a movie.

First, I choose "Show Movie" from the 3D menu.  I start to create the movie by dragging any one of the bookmarks from the bookmark pane to the movie pane.

This creates a keyframe in the movie which is by default 10 frames in length.  I can change the length by clicking and dragging the end of the keyframe to the length I want.  I then drag a second keyframe to the movie pane. 

When I play the movie, by clicking on the play button just above the movie, the volume will gradually change in appearance from the first bookmark to the second, and the time it takes to do this will depend on the length I have set for the keyframe.  I can edit a keyframe by double-clicking on a keyframe or selecting "Edit Keyframe..."from the 3D menu to access the Edit Keyframe dialog.

This dialog allows me to configure of the length of the keyframe or transition and also select which of the bookmark properties to use in that transition. So I can if I wish use only the positional information and not the rendering settings stored with a keyframe.

I continue to add more bookmarks to the movie pane until I have the movie I want to show the world.

The example I’m using here is a single timepoint, but if I have a time lapse sequence of volumes, I move from one timepoint to the next within the movie by selecting "Add Timepoint Sequence..."from the 3D menu. This will add a time bar to the movie which can be configured to last any number of frames, switching between timepoints backwards or forwards and even switching between a subset of timepoints.

I can double-click on the timepoint sequence or select "Edit Timepoint Sequence..." from the 3D menu to access the Edit Timepoint Sequence dialog.

I use this to adjust the number of frames over which the timepoints will be played through, and my movie can switch between timepoints either backwards or forwards.  I can also configure a timepoint sequence to switch between a subset (or range) of timepoints. Additional timepoint sequences may be added to the movie to switch through remaining timepoints.

Now comes the bit I really like in Volocity 4 movie making.  I like to get my timings just right when making presentations, but it can be tricky to make my movies just the right length.  Well, now my problem is solved!

I select "Resize Movie..."from the 3D menu to easily change the length of the movie. I change the movie length to a percentage of its existing frame number, or to a fixed number of frames, or to last a known length of time when played at a known frame rate.  So when I know how long I want to speak about my movie, I can make it last for the right length – no more embarrassing silences!

I can save a movie to use again by selecting "Save Movie..." from the 3D menu and giving it a name.  The movie is stored as a preference.  This is just storing the set of instructions not the movie frames.

To actually create the movie frames when I’m happy with what I have made, I select "Make Movie"from the 3D menu to create the movie frames and add them to the library. A new folder will be added to the library. The name is the same as the source data with ‘Movie’appended.

I then export this folder as a movie by selecting it and choosing "Export..."from the File menu.  For more information about the export choices, I suggest you consult the Volocity User Guide, as I think I’ve said enough for this time!

By the way, if you are one of those people who loves playing video games, why not plug yourself into Volocity with your gamepad to navigate your volumes and create your bookmarks? It’s all in the User Guide. Have fun with your movies!