You can optimize how a dataset is displayed by understanding all of the
attributes that are available to you in the playlist.sos files. You can do much
more than simply display the dataset.
The Visual Playlist Editor can be used to create both presentation playlists and playlist.sos
files and gives you the ability to set all the attributes that are available
through an intuitive user interface. All of the attributes available for
playlists can be found in the Playlist Format Reference.
For a texture dataset, there are only a few attributes that you need to
consider. When a texture dataset is initially loaded on the sphere, you can set
whether you want it to rotate immediately or only after play is pressed. The
attribute animate in the playlist controls this. If animate is not included
in the playlist, then the default is for the dataset to automatically start
rotating. animate can be set to either 0 or 1. 0 will prevent the dataset
from animating until play is pressed, and 1 will cause the dataset to start
rotating immediately when loaded. For a texture, fps is used to define how
fast the dataset will rotate, while for a time series, it defines the animation
rate. Another common attribute used with textures is the tilt option. For
instance, we have our Earth textures set to load at a 23.5° tilt to resemble
the Earth’s actual tilt. This is also useful if you are loading a dataset that
highlights the poles, which are hard to see if there is no tilt. To set the
tilt, set tiltx, tilty, and tiltz to the number of degrees that you want
each axis tilted. The tilt can be positive or negative.
For a time series, you have all of the attributes mentioned for the texture,
plus many more. Rather than causing a dataset to rotate, animate causes a
time series to start animating, but the functionality is the same. The default
is for the dataset to start animating immediately. When a presentation is
docent-led, it is often helpful to have the time series animate only after
play has been pressed. This gives the docent time to provide background
information about the dataset and explain what is going to happen. (In Autorun
mode “animate” is automatically set to 1 regardless of what is in the
playlist.) Another option is to set firstdwell, which is an amount of time
that the system lingers on the first frame before animating. The default is
zero seconds. The time is listed in milliseconds, so firstdwell = 4000 will
dwell on the first frame for 4 seconds. You can also dwell on the last frame by
setting lastdwell. When lastdwell is not set, the dataset loops
continuously without pausing. Especially with model data, it is nice to set
lastdwell so that the audience can get a good look at the last frame before
the dataset loops again.
With particularly long datasets it’s sometimes nice to show only a piece of the
dataset. You can do that by setting the startframe and endframe to the
frame numbers that you want to start and end on. An example of when to use this
would be if you just want to show a loop of Hurricane Katrina, not the entire
2005 season. You would use the 2005 Hurricane dataset, but set the startframe
and endframe so that only the piece of the dataset when Hurricane Katrina was
visible is shown. The endframe can be a negative number, which counts back
from the end. Another way to shorten a dataset is to set the skip option,
which allows you to set a skip factor. When skip is set to one, it skips
every other image, and when it’s set two, it plays every third image.
To stop an animation, you can simply pause a dataset with the remote. But if
you want to stop on an exact frame, then you should use stopframe in the
playlist. This lets you set an exact frame that you want the animation to stop
on and start animating again after you press play. This is a good feature to
use with model data when you want to look at a particular year. To proceed past
the frame that you stopped on, you must advance one frame and then press play.
Another option that you have for times series is to not only have them
animating, but also rotating. For example, the default for the Indian Ocean
Tsunami dataset is for the base image to stay stationary while the waves
propagate across the ocean. This means that only the audience standing in front
of the Indian Ocean can see the waves. When zrotationenable is set to 1, then
the dataset will rotate about its z axis while it animates. You can also use
zfps and zrotationangle to set the frames per second rate for the dataset
and the angle at which the dataset rotates. Make sure that you set your zfps
at a rate that allows your audience to still grasp what they are looking at
before it rotates out of site. For especially busy animations, it could be
distracting to the audience to see both the animation and the rotation.
There are also some functions in the playlist that should be specified when
using Autorun. Autorun cycles through the datasets in a playlist automatically,
showing each dataset for a specific amount of time. You can specify the amount
of time each dataset is shown by setting timer to the number of seconds
desired. If this is not specified, then each dataset is shown for 180 seconds.
If timer is specified and you are not showing the playlist in Autorun mode,
then timer will be ignored. It’s important to use timer when you also have
accompanying audio tracks so that the dataset is shown for the length of the
audio track. You will want to make sure that the audio is synced with the
playlist. You can set audio for each dataset by specifying the desired track
with the “audio” attribute. The audio tracks must be compatible with the Linux
mplayer such as .mp3, .mp4, .wav, or .ogg. Audio tracks are available from NOAA
for a limited number of datasets. They provide a good way to give your audience
information when a docent is not available.
In order to restart a dataset, including the audio and any PIPs that have been
added, the duration attribute needs to be set for the length of the dataset in
seconds. If duration is not set, the dataset will loop indefinitely, but the
audio and the pips will not loop.