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Advantages disadvantages and applications of motion capture

Advantages

Mo cap offers several advantages over traditional computer animation of a 3D model:

More rapid, sometimes even real time results can be obtained.

The amount of work does not vary with the complexity or length of the performance to the same degree when using traditional techniques.

Complex movement and realistic physical interactions such as secondary animation, weight and exchange of forces can be more easily recreated in a physically accurate manner.

Mocap technology allows one actor to play multiple roles within a single film.

Advantages over live action A movie that contains so large amounts of CGI that the actors would have to stay in front of a bluescreen and interact with invisible computer animated characters which is added later, trying to fit into a computer animated world, it is sometimes less problematic to make everything digital, including the actors. This way, all elements would fit together naturally and have the same visual look.

The director can choose any angle he desires from a scene, including angles that would have been hard or impossible in a live action movie.

Limitless possibilities for rotating effect.

Costumes, make-up, body size and age can be changed to whatever is needed.

There is no need to have light, colors and filters in mind when filming the motions, as this will be added digitally later.

Disadvantages

Specific hardware and special programs are required to obtain and process the data.

The cost of the software and equipment, personnel required can be prohibitive for small productions.

The capture system may have specific requirements for the space it is operated in.

When problems occur it is sometime easier to reshoot the scene rather than trying to manipulate the data. Only a few systems allow real time viewing of the data to decide if the take needs to be redone.

Applying motion to quadruped characters can be difficult.

The technology can become obsolete every few years as better software and techniques are invented.

The results are limited to what can be performed within the capture volume without extra editing of the data.

Movement that does not follow the laws of physics generally cannot be represented.

Traditional animation techniques such as added emphasis on anticipation and follow through, secondary motion or manipulating the shape of the character as with squash and stretch animation techniques are generally not applicable.

If the computer model has different proportions from the capture subject artifacts may occur. For example, if a cartoon character has large, over-sized hands, these may intersect strangely with any other body part when the human actor brings them too close to his body.

The real life performance may not translate on to the computer model as expected.

Applications

Some video games use motion capture to animate athletes, martial artists, and other in-game characters.

Movies use motion capture for CG effects, in some cases replacing traditional cell animation, and for completely computer-generated creatures, such as Gollum, The Mummy, and King Kong.

In producing entire feature films with Computer animation, the industry is currently split between studios that use Motion Capture, and studios that do not. Out of the three nominees for the 2006 Academy Award for Best Animated Feature, two of the nominees (“Monster House” and the winner “Happy Feet”) used Motion Capture, and only Pixar’s Cars was animated without Motion Capture. In the ending credits of Pixar’s latest film “Ratatouille,” a stamp appears labelling the film as “100% Pure Animation — No Motion Capture!” On the other hand, Pixar’s parent The Walt Disney Company has announced that it will distribute Robert Zemeckis’s “Christmas Carol” to be produced using “Performance Capture,” the motion-capture approach that Zemeckis first used on “Polar Express.”

Virtual Reality and Augmented Reality require real time input of the user’s position and interaction with their environment, requiring more precision and speed than older motion capture systems could provide. Noise and errors from low resolution or low speed systems, and overly smoothed and filtered data with long latency contribute to “simulator sickness” where the lag and mismatch between visual and vestibular cues and computer generated images caused nausea and discomfort.

Gait analysis is the major application of motion capture in clinical medicine.

High speed—high resolution active marker systems can provide smooth data at low latency, allowing real time visualization in virtual and augmented reality systems. The remaining challenge that is almost possible with powerful graphic cards is mapping the images correctly to the real perspectives to prevent image mismatch.

Motion capture technology is frequently used in digital puppetry systems to aid in the performance of computer generated characters in real-time.

by

Antony

GSM phones use encrypted technology that enables secure voice and data transfer during calls. GSM technology uses an algorithm to ensure the authenticity of the caller and the integrity of the channel, even when you are roaming in a foreign country.

The most interesting, and potentially contentious area of wireless security is that concerning wireless LANs or Wi-Fi networks, these are fast becoming the connection method of choice. Wireless signals do not recognize corporate or geographical boundaries and are only limited by the propagation configuration of the network. Even in an office environment you will find small areas or “blind spots” where the coverage is very weak or non-existent. So, it is possible for the random surfer to “happen upon” on someone else’s network. How can one?protect against this happening?

Wireless local area networks use spread-spectrum technology – a technique that makes the radio signals difficult to intercept. Most Wi-Fi systems also include a form of user logon and password protection. Of course, the spread spectrum signals can be intercepted with a relatively simple wireless card and many networks do not properly set up the password feature and will allow ready access to anyone. The fact that “employees” have to go through some form of physical security before they can access the network only adds to the notion that wireless networks may not be as secure as equipment manufacturers would have us believe.

The problem with wireless security is essentially a technical issue with the way the signals are encrypted. The original wireless LANs (WLANs) used the Wireless Encryption Protocol (WEP). This was then replaced in late 2002 with the Wi-Fi Protected Access (WPA). Essentially, WPA offered improved data encryption through the use of temporal key integrity protocol (TKIP). The TKIP feature scrambles the keys using a hashing algorithm and ensures that the keys have not been tampered with. WEP only uses a static key that is seldom changed by users. This cryptographic weakness caused many of the security breaches in WLANs because intruders could, with relative ease, generate an encryption key and access a wireless network.

While WPA offers enhanced security features over WEP, not all industry observers are completely satisfied. A recent problem was highlighted with WPA concerning the use of poorly chosen passwords for a network. Criminals intent on compromising a WLAN can use simple dictionary software to overcome the system password. In fairness, this weakness only manifests itself when short, text-based keys are used and does not signify a fault in the WPA protocol. WLAN manufacturers can circumvent this problem by incorporating the ability to generate random keys across the network and putting in place user requirements concerning the length and style of passwords.

Microsoft responded to this potential threat by providing a Windows XP download that alters the way the operating systems communicates with the Wi-Fi network – using separately generated keys for each system user rather than one, albeit encrypted, key for the network connection

Children today consider wireless phones as necessary and usual in daily life. They don’t know a time without them being prevalent. But that was not the case in 1973 when Martin Cooper made his first cellular phone call from a New York City street and New Yorkers stared gaping at him. But the history of cell phone starts further back in time.

The history of cell phones or wireless communications must start with Samuel Morse. He introduced the concept of wireless by conduction when he transmitted a telegraph signal through water. His telegraph was the first device to transmit messages by electricity.

Then in 1843 a man by the name of Michael Faraday studied to see if space could conduct electricity. In 1865 a dentist, Dr. Mahlon Loomis was the first person to communicate through wireless via the atmosphere. He came up with the idea of transmitting and receiving messages using the atmosphere as a conductor and sending up kites covered with copper screens that were linked to the ground with copper wires. Loomis was awarded a $50,000 research grant by congress.

But let us move forward to the twentieth century and the invention of the cell or wireless phone as we know it today. This brings us to a man often referred to as the father of the cell phone, Martin Cooper. He was employed by Motorola and worked on developing the first hand held radios made for the Chicago police department in 1967. He then went on to lead Motorola’s cellular research.

AT&T’s, Bell Laboratories introduced the idea of cellular communication in 1947. Through the 60′ and 70’s Motorola and Bell Laboratories were in a race to incorporate the technology into portable devices.

On April 3, 1973 Martin Cooper won the race when he placed the first cell phone call to his rival at AT&T. Motorola introduced the 16-ounce “DynaTAC” phone into commercial service in 1983, at a cost to the consumer of $3,500. It weighed 2.5 lbs. took 10 hours to charge with 35 minutes of talk time. Features were limited to dial, listen and talk. This was commonly referred to as the Brick.

In 1977 cell phones went public. Chicago was the first city to trial cell phones with 2000 customers.

In 1983 Motorola, with the help of Martin Cooper, introduced the 16-ounce “DynaTAC” the first truly portable cellular phone. This phone took 15 years and a cost of over 100 million dollars to come to market. The cost to the consumer was $3500. It weighed 2.5 lbs., took 10 hours to charge and allowed 35 minutes of talk time. Features were limited to dial, listen and talk.

From 1983 to the late 1980″s 1st generation cellular or car phones as they were often called became very popular. Most were not hand held but rather installed in cars or bag phones.

In 1988 the CTIA (Cellular Technology Industry Association) was founded.

In the early 1990’s second generation or 2G phones came onto the market. They were able to work on GSM, TDMA, and CDMA technology. 2G digital networks were online and replacing the analog network frequencies making them virtually obsolete. The phones became much smaller and portable and usage soared.

Currently third generation or 3G phones are the technology available today. 3G phones include innovations that allow them to receive more than just phone calls. For example Internet access and email capability and streaming video.

In December 2005 the wireless industry in the US surpassed the 200 million subscriber mark. In 2006 that number grew to 233 million subscribers with 12.8% of households being totally wireless. There are 195,613 cell sites making this possible.