Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave

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by Olivier
Michon

In this tutorial, we will show how powerful the
combo of Aura [2] + LightWave^® [6.5]
is to add tracking to LightWave.
Step 1 - Aura:

Load the sequence you want to track into
Aura ( Make sure the Pre-Load option is ON).
Here, we will use the 60 first frames of CarSide.AVI located
on the AuraContentAnims from the Aura CD.
Open the Filters > Motion > Pixel
Tracker panel.
At frame 0, set up some suitable parameters
for the Pixel Tracker to achieve a nice wheel
tracking.
Define the closest track area and the appropriate
search area assuming the track area could not
be out of the search area when you go to the
next frame.
Set Reference to Dynamic if
the tracked area is changing a lot.
Then, select the RGBA channel where you
have the best contrast.
Finally, define the appropriate sub-pixel
accuracy depending on the kind of motion and
the precision you want to achieve.

<table align="center" border="0" cellpadding="2" cellspacing="2">
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<td rowspan="2"> Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Panel_pixel_tracker

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Panel_pixel_tracker

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<td> Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Screenshot_tracker_alignment

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<td> Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Screenshot_tracker_path

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Now, use Select All to select all
of the frames in the layer, then apply the
filter to perform the track.
To export the motion file to LightWave® open
the Path Manager panel. You can do this
through theMotionmenu on the
Pixel Tracking panel or through Filters->Motion->Path
Manager. Select the path you've just tracked.
Choose File->Export to LW Motion.
Name it wheel_track.mot.
Make sure the Reverse Y is ON in
the first tab, and Image Ratio, located
in the second tab should also be ON to
get the proper path in LightWave®. We want
to export the motion information so leave the
Motion option checked on the Channels tab.
Once this is set, hit Export to save
the file.

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Panel_export_origin

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Panel_export_scale

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Panel_export_channels

What we have to do now is to prepare an
image in which we will copy the tracked area
of the first and last frame in the same single
frame.
For that, use the Circle Select tool to
isolate the tracked region on the first frame.
Inverse the selection, then clear it. Do
the same for the last frame in the sequence.
Now, copy the last image to a new layer,
then move this layer at time 0, so that it
matches the first frame of the sequence.
Merge the two layers, then export the first
frame as BG_layout .tga.
It should result the following image.

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Merged_background_t

This image will help us to lock the camera
at the right place so that the object that
will receive the path would match the sequence,
but this is the next step.

Step 2, LightWave^®:

Launch Layout.
Add a Null object named start_Null,
then load the motion file wheel_track.mot as
its motion.
Clone this Null object and rename it end_Null.
Open the Graph Editor to modify the end_Null object
motion.
Select all end_Null.Position channels,
then select all keys except the last one.
Delete the selected keys and move the only
resulting key at frame 0. It should result
the following image:

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Screenshot_path

Now, load the BG_layout .tga file
and use it as a Background image.
Display the Background image in the Camera
View Background (from the Display Options panel).
You have to set the proper Lens Focal
Length to match the real camera
lens.
Then in the Camera View, move the Camera
to match the start_Null and the end_Null on
the corresponding tracked areas of the Background
image.
In this example, it should be around :
<blockquote> X = 0 m
Y = 0 m
Z = -1.2 m

Note: If you have set the
origin of the path to the center of the screen
(default setting), you should have to move
the camera only on Z axis.</blockquote>
Now, replace the BG_layout .tga by
the CarSide.AVI and the start_Null object
will match the wheel position just like the
Pixel Tracker does in Aura.
To add a particle effect at the contact
point between the wheel and the road, you just
have to add an additional Null object parented
to the start_Null, to create
an offset between the center of the wheel and
its base, then put an FX_emitter on this new
Null object.
You may have to adjust this offset during
the animation due to the perspective deformation.

Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Pixeltrack_particles

MPEG
Movie - Two Pixel
Tracks Plus Particles

Enjoy !

]

1 Tutorials LightWave 3D Export Aura [2] Pixel Tracking to LightWave Qua Jan 26, 2011 2:12 am

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