Graphics Reference
In-Depth Information
Muting Nodes
Asyou'veworkedwithslightlylargernodenetworks,youmayhavenoticedthatchangingvalues,reconnecting
nodes, or making other adjustments or modifications can take a while because of the need for Blender to recal-
culate theeffects ofall thenodeseach time achange ismade. Youcanmitigate this problem bymuting selected
nodes when you don't need them. You can mute and unmute nodes by pressing the M button with your cursor
over the node. Muted nodes' names appear in square brackets on the top of the node, and a red curved line is
drawn across the face of a selected muted node.
Learning More about Compositing
ThischapterhasbarelyscratchedthesurfaceofwhatyoucandowiththeBlendernodesystemintermsofvideo
compositing. There is a great deal more to learn about Blender's compositing functionality, but it is even more
important to study the fundamentals of how 2D images are composited with each other. Coupled with what you
have learned here about working with nodes, a thorough grounding in compositing will give you all the know-
ledge you need to get exactly the effects you are after. For this information, there is no better place to look than
Ron Brinkmann's
The Art and Science of Digital Compositing, Second Edition: Techniques for Visual Effects,
Animation and Motion Graphics
(MorganKaufmann,2008).Thisistrulythebibleofcompositingandisamust
for anybody serious about understanding what they are doing and why in compositing. There is also an excel-
lentwebsitefullofinformationaboutthebookandaboutcompositingat
www.digitalcompositing.com
.Ihighly
recommend checking it out as you continue to deepen your skills in compositing with Blender.
The Bottom Line
Use the Blender composite node system to pull a green screen matte.
When you know in advance that
you will be compositing a character or object into a scene, a common technique is to shoot the original video
of the foreground figure against a colored background screen. This makes it possible to eliminate the back-
ground quickly and easily by using color channels in the node compositor.
Master It
Using a nodes setup based on the example in this chapter, add a background image from an
image file to create a fully composited image such as the one shown in
Figure 9-64
.
You can use the
sky_map.jpg
file included on the CD.
Use the AnimAll add-on for garbage matting.
Background clutter in the original footage can cause im-
perfections in the matte. To block these out, garbage matting is used. In cases when the garbage matte must
interact with the silhouette of the foreground figure, some hand keying or rotoscoping may be necessary.
Master It
Usinga3DcurveanimatedwiththeAnimAlladd-on,addasecondgarbagemattetothevideo
example used in this chapter to cover the debris in the background of the right side of the frame.
Manipulate the video's color channels to reduce color spill.
Any time you composite footage shot under
one set of lighting conditions with footage shot under another set of lighting conditions, color mismatches
can occur. This is particularly the case when a green screen is used, which can cause a green cast or spill in
the original footage. To eliminate this, it is possible to work directly with the color channels to adjust the mix
of red, green, and blue energy in the image to better match the background.
