Digital Earth: TerraVision: User Guide


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•	Cmd Line Opts
•	Tcl/Tk Version
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	• Paths Menu
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Digital Earth > Terravision^TM > User Guide > Tcl/Tk > Paths Menu

The Paths Menu

The Path menu provides access to all of TerraVision's flight path capabilities. This lets you record a certain flight path through the terrain and play this back. You can save flight paths for use at a later date, and even save a flight path to a series of images for creating movies.

New Path

This option lets you create a new path. If you already have a path file loaded, then it will be removed from memory. You are then presented with a user interface for managing the creating of your new flight path. This is exactly the same as the interface for "Edit Path", below.

Load Path...

This option will let you load TerraVision fligh path file. Flight path files contain a list a viewpoints which TerraVision interpolates between in order to produce a fly-through animation. These are stored as plain ASCII text files in a directory with the same name as the terrain dataset, which in turn lives in the directory paths from your configuration directory ($HOME/.tv/ under Unix, or the config subdirectory of the installation location under Windows.) For your information, a path file looks like:


#PATH V1.0

$interpolate = linear
$name        = Irwin Test Flight
$update_rate = 30
$speed       = 2000
$loop        = yes
$gcc         = yes

x=-4444.57 z=-1746.71 y=7634.46 yaw=0.4732 pitch=2.134 roll=0
x=1802.74 z=942.15 y=3173.27 yaw=0.4569 pitch=2.177
x=8908.53 z=-3449.30 y=7902.57 yaw=2.0751 pitch=2.333
x=11967.45 z=1492.28 y=4728.7 yaw=2.8615 pitch=2.115
x=12322.39 z=9028.90 y=3047.98 yaw=3.7999 pitch=1.835
x=8871.02 z=6391.788 y=1787.71 yaw=3.7885 pitch=1.821
x=5230.81 z=3640.53 y=973.24 yaw=3.7905 pitch=1.745

Save Path As...

This option will let you save the current flight path to disk. Once you have saved a flight path to disk, you can recover it by using the "Load Path..." menu option.

Edit Path

The Edit Path path let's you control all of the parameters that define a single flight path. The interface looks like this:

A flight path is essentially composed of a number of viewpoints that TerraVision flies between. You can create a flight path interactively by just pressing "Add" at each successive viewpoint you want to add to the flight path. Once you have added a few viewpoints, then you can see what your flight path looks like by selecting the "Path/Play" option.

The other buttons next to "Add" include, "Delete" which lets you remove a viewpoint from the list of viewpoints, "Move up" and "Move down" which let you bubble viewpoints up and down the list, "Update" which updates the currently selected entry in the path with the current camera position, and "Duplicate" which creates a duplicate of the selected path entry.

Other flight path features that you can control include the velocity, whether the flight path will continually loop, whether TerraVision will automatically close the loop from the last viewpoint to the first one, and also whether you want to do linear or spline (or no) interpolation for the flight path.

Play

Play the currently loaded flight path from the beginning.

Stop

Stop the current flight path animation

Continue

Play the currently loaded flight path from the point at which it was last stopped, or from the beginning if you have not previously stopped an animation.

Goto Start

Jump to the very first frame of the flight path animation, but do not animate.

Goto Next

Jump to the next viewpoint in the flight path file (do not animate).

Goto Prev

Jump to the previous viewpoint in the flight path file (do not animate).

Goto End

Jump to the very last frame of the flight path animation, but do not animate.

Save to Images

There a couple of menu entries at the bottom of the Paths menu called "Save to Image (320x240)" and "Save to Images (480x360)". These options will play the currently defined flight path, but will stop at each frame until all tiles have been loaded into the viewer and then it will save that frame to an image file on disk. The images are saved in the current directory, in a binary PPM format, with the general filename "tvimage<fn>.ppm", where fn is the frame number of that image.

This option is useful for creating movie files of TerraVision flythroughs, e.g. MPEG, AVI, QuickTime, etc.. There are various utilities out there that can take multiple images and create a movie file. For example, the registered version of QuickTime, or the Berkeley MPEG encoder. Many of the most recent movie files from the TerraVision Movies web page were produced using this facility.