After Effects cs4 note

Composite in After Effects


This is a book about visual effects compositing. If you
use Adobe After Effects, the goal is to help you create
believable, fantastic moving images from elements that
were not shot together, and to do it with the least possible
effort. This fi rst section of the book focuses on effortlessness,
offering a jump-start (if you’re new) or a refresher
(if you’re already an After Effects artist) on the After
Effects workfl ow.
To be an outstanding compositor, you need to employ your
best skills as both an artist and an engineer. As an artist,
you make creative and aesthetic decisions, but if you are
not also able to understand how to put those decisions
together and how the process works, the artistry of your
work will suffer. Artists and engineers have much in common:
both understand and respect the tools, both know
that the tools themselves don’t make you a great designer,
and in both roles, iteration—multiple refi nements—are
often what separates a great effort from mediocrity.
This chapter and the rest of Section I focus on how to get
things done in After Effects as effortlessly as possible. It is
assumed that you already know your way around the basics
of After Effects and are ready to learn to work smarter.
Workspaces and Panels
Figure 1.1 is one way of looking at the most generic of
projects: it shows the Standard workspace that appears
when you fi rst open After Effects CS4, broken down into
its component parts. The interface consists of
If this book opens at too advanced
a level for you, check out Adobe
After Effects CS4 Classroom in a Book
(Adobe Press), a helpful beginner’s
resource.
5
I: Working Foundations
Figure 1.1 The Standard workspace layout, diagrammed in color. The top areas in red are informational only, while the
purple areas contain tools and settings. The blue areas of the Timeline and Effect panel contain stacks whose order will
change compositing order. Panel tabs, in yellow, can be grabbed to reorder the interface and contain menus at the upper
right to adjust their appearance. The layer stack, in green, is modal and can be swapped for the Graph Editor.
. The main application window contains some panel
groups—six of them by default (the Standard workspace),
as few as two (Minimal workspace), or as many
as 17 (All Panels workspace).
. Each group contains one or more panels each with a
tab in the upper left.
. Separating the panel groups are dividers; panels and
dividers are dragged to customize the workspace (more
on that in a moment).
. Some panels are viewers, with a pop-up menu in the tab
listing available clips.
. At the top is the Tools panel, which can be hidden but
only appears atop the application window (and thus has
no tab).
I call these out here to be done identifying them and to
reassure you that this, along with a bunch of menus and a
bunch more twirly arrows, is all there is to the After Effects
user interface.
All available panels in After Effects
are listed under the Window menu;
the most common include preset
keyboard shortcuts. Use these as
toggles to keep your workspace
clutter-free.
6
Chapter 1 Composite in After Eff ects
Are you a Zen roshi? Reveal the core essence of After
Effects with the Minimal workspace (via the Workspace
menu in Tools or Window > Workspace). Two of the most
important three panels in After Effects are
. The Composition panel, a viewer where you examine a
shot
. The Timeline panel, the true heart of After Effects,
where elements are layered and timed for individual
compositions (or shots). You will typically have many of
these open at any given time.
For the third, choose Window > Project (Cmd/Ctrl+0)
to add the Project panel. This is the Finder or Windows
Explorer of After Effects—nothing more than fi les and
folders representing the contents of your project.
At some point even a Zen roshi will assumedly need at least
two more panels. A completed composition typically goes
to the Render Queue (Cmd/Ctrl+Alt/Option+0) for fi nal
output (details about this important hub are found at the
end of the chapter), and you are likely to add layer effects
which are best adjusted in the Effect Controls (with a layer
selected, F3 or Cmd/Ctrl+Shift+T), although most the
same controls can be found by twirling open the layer with
that essential little triangle to the left of the layer name.
Other panels (found in other workspaces, or by selecting
them under the Window menu) contain controls for specifi
c tools such as paint (Paint and Brush Tips), the most
signifi cant of which are covered in detail later in the book.

Optoelectronic imaging and detection with hybrid photon detector

1. Introduction

The basic concept of Hybrid Photon Detectors (HPDs) is known since 1957 . It was pursued further in the 1960. In recent years, further work on HPDs was started , profiting from improved performance of silicon PIN-diodes. Our new concept of an optoelectronic camera.

2. State of the art

2.1. Hybrid Photomultiplier Tubes (HPMTs) These devices consist of small silicon PIN diodes (anodes) bombarded in the cross-focusing mode (Fig. 1) with accelerated (B15 kV) photoel- ectrons from photocathode’s of much larger areas.

The tiny anode sizes (B2mm diameter)

result in small diode capacitance and low leakage currents. Together with the comparatively large number of electron–hole pairs (278/keV) per absorbed photoelectron, these properties lead to small signal fluctuations.These peculiarities make HPMTs particularly suited for photon counting, which is clearly demonstrated by comparing Fig. 2a (from Ref.[14]) with Fig. 2b (from Ref. [15]). Both figures show photoelectron peak distributions measured with the same experimental arrangement, one (Fig. 2a) taken with an HPMT and the other one (Fig. 2b) with a photomultiplier. Although this photomultiplier (Quantacon 8850)1 was particularly designed for photon counting, it resolved less photoelectron peaks due to its higher statistical fluctuations.HPMTs can also replace photomultipliers in gamma spectroscopy. Besides their small statistical fluctuations.

HPMTs profit in this application from their increased photoelectron collection efficiency. This results from their B15 kV electric acceleration field as compared to the modest voltage (B400V) of photomultipliers, applied between photocathode and their first dynode.

2.2. Imaging Silicon Pixel Array (ISPA) tubes

ISPA-tubes are alternative devices for image intensifiers. They represent a one-stage optoelectronic camera in contrast to the multi stages of image intensifiers needed to achieve the required light amplification. As displayed 

photons from a radiation detector strike the ISPA-photocathode. They generate photoelectrons, which are electro statically accelerated in the proximity focusing mode to 25 keV onto silicon pixels at the ISPA-anode.

It consists of a finely segmented matrix with rectangular or square PIN-diodes, some 50 mm_500 mm or 200 mm2 in size. Each detector pixel is bump bonded to its proper and equally sized electronic pixel (Fig. 3b), which comprises preamplifier, comparator, delay line, coincidence logic, and memory [16]. Their total read-out time amounts to less than 10 ms, far surpassing the several milliseconds of a CCD. The small pixel areas and the direct bonding between detector and electronics reduce considerably the input capacitance of the preamplifier.

This provides low noise levels that are essential for the contrast in optoelectronic images. The contact layer of the pixel chip (Fig. 3a) serves as an electrode for the chip bias voltage. Each time one or more photoelectrons hit the anode chip, they generate a fast (B10 ns) electronic pulse. These analogue signals allow for self-triggering of ISPA                                       fig.3 tubes and enable the suppression of unwanted              background events by setting appropriate energy windows.

ISPA tubes have been successfully applied for particle tracking with scintillating fibres. Track images from square fibre bundles each comprising 1600 hexagonal-shaped 60 mm individual fibres, which have been exposed to a 120 GeV/c negative pion beam [13], are shown in Fig. 4. The particle tracks are composed of micro-vectors [17] with 100 mm (FWHM) residuals, which indicate the two-track resolution.

This exposure confirms that ISPA tubes improve considerably the read-out of scintillating fibres compared with the bulky intensifier chains [18,19] and their CCD-read-out.Self-triggering can be applied to suppress ghost tracks due to showers from gamma pair-conversions and particle multiplicities due to secondary interactions.For their application in beta radiography, thin planar discs of organic beta detectors are mounted in front of ISPA tubes to image their scintillations. To measure the achieved spatial resolution, we placed a brass template with slit patterns (Fig. 5a) between the beta sources and the detector discs.