Chroma key compositing, or chroma keying, is a visual effects/post-production technique for compositing two images or video streams together based on colour hues. The technique has been used in many fields to remove a background from the subject of a photo or video – the newscasting, motion picture, video game industries. A colour range in the foreground footage is made transparent, allowing separately filmed background footage or a static image to be inserted into the scene; the chroma keying technique is used in video production and post-production. This technique is referred to as colour keying, colour-separation overlay, or by various terms for specific colour-related variants such as green screen, blue screen and magic pink. No part of the subject being filmed or photographed may duplicate the colour used as the backing, it is used for weather forecast broadcasts, wherein a news presenter is seen standing in front of a large CGI map during live television newscasts, though in actuality it is a large blue or green background.

When using a blue screen, different weather maps are added on the parts of the image where the colour is blue. If the news presenter wears blue clothes, his or her clothes will be replaced with the background video. Chroma keying is common in the entertainment industry for visual effects in movies and video games. Prior to the introduction of travelling mattes and optical printing, double exposure was used to introduce elements into a scene which were not present in the initial exposure; this was done using black draping. George Albert Smith first used this approach in 1898. In 1903, The Great Train Robbery by Edwin S. Porter used double exposure to add background scenes to windows which were black when filmed on set, using a garbage matte to expose only the window areas. In order to have figures in one exposure move in front of a substituted background in the other, a travelling matte was needed, to occlude the correct portion of the background in each frame. In 1918 Frank Williams patented a travelling matte technique, again based on using a black background.

This was used in many films, such as The Invisible Man. In the 1920s, Walt Disney used a white backdrop to include human actors with cartoon characters and backgrounds in his Alice Comedies; the blue screen method was developed in the 1930s at RKO Radio Pictures. At RKO, Linwood Dunn used an early version of the travelling matte to create "wipes" – where there were transitions like a windshield wiper in films such as Flying Down to Rio. Credited to Larry Butler, a scene featuring a genie escaping from a bottle was the first use of a proper bluescreen process to create a traveling matte for The Thief of Bagdad, which won the Academy Award for Best Special Effects that year. In 1950, Warner Brothers employee and ex-Kodak researcher Arthur Widmer began working on an ultraviolet travelling matte process, he began developing bluescreen techniques: one of the first films to use them was the 1958 adaptation of the Ernest Hemingway novella, The Old Man and the Sea, starring Spencer Tracy. Petro Vlahos was awarded an Academy Award for his refinement of these techniques in 1964.

His technique exploits the fact that most objects in real-world scenes have a colour whose blue-colour component is similar in intensity to their green-colour component. Zbigniew Rybczyński contributed to bluescreen technology. An optical printer with two projectors, a film camera and a'beam splitter', was used to combine the actor in front of a blue screen together with the background footage, one frame at a time. In the early 1970s, American and British television networks began using green backdrops instead of blue for their newscasts. During the 1980s, minicomputers were used to control the optical printer. For the film The Empire Strikes Back, Richard Edlund created a'quad optical printer' that accelerated the process and saved money, he received a special Academy Award for his innovation. For decades, travelling matte shots had to be done "locked-down", so that neither the matted subject nor the background could shift their camera perspective at all. Computer-timed, motion-control cameras alleviated this problem, as both the foreground and background could be filmed with the same camera moves.

Meteorologists on television use a field monitor, to the side of the screen, to see where they are putting their hands against the background images. A newer technique is to project a faint image onto the screen; some films make heavy use of chroma key to add backgrounds that are constructed using computer-generated imagery. Performances from different takes can be composited together, which allows actors to be filmed separately and placed together in the same scene. Chroma key allows performers to appear to be in any location without leaving the studio. Computer development made it easier to incorporate motion into composited shots when using handheld cameras. Reference-points can be placed onto the coloured background. In post-production, a computer can use the references to compute the camera's position and thus render an image that matches the perspective and movement of the foreground perfectly. Modern advances in software and computational power have eliminated the need to place the markers – the software figures out their position in space (a disadvantage of this is that it

"Is That Your Chick" is the second single from Memphis Bleek's second album, The Understanding. The single version featured Missy Elliott; the album version featured a verse from Twista and another verse from Jay-Z. The song was produced by Timbaland and was released in 2000; the original version of the song appeared on the European version of Jay-Z's Vol. 3... Life and Times of S. Carter. Memphis Bleek recorded verses for the song, it was released as the second single from Bleek's The Understanding. In the alternate version the chorus is changed from "Cause that's Jay and them..." to "Cause that's Bleek and them...". The song is noted to be Bleek's last song to chart on Billboard Hot 100; the official music video for the song was directed by Chris Robinson. The video version of the song is 1 Jay-Z verse. Twista does not appear in the video

"Stay" is a song by South Korean girl group Blackpink. It was released on October 31, 2016, together with "Playing with Fire", as a digital single titled Square Two by YG Entertainment. On October 27, 2016, teaser images of all four members of Blackpink were released for the second title track "Stay" of their single Square Two. On October 30, YG Entertainment released the behind-the-scenes video of the music video for "Stay", they performed their comeback stage for "Stay" and "Playing with Fire" on November 6 on SBS's Inkigayo, on Mnet's M Countdown on November 10, 2016. The music video for "Stay" was directed by Han Sa Min, who directed "Gotta Be You" by 2NE1 and "Sober" by Big Bang, it was released on Blackpink's official YouTube channel at midnight on October 31, 2016 KST. As of July 2019, the video has surpassed over 170 million views

Juyong Pass is a mountain pass located in the Changping District of Beijing Municipality, over 50 kilometers from central Beijing. The Great Wall of China passes through, the Cloud Platform was built here in the year 1342. Juyongguan is in the 18-kilometer -long Guangou Valley; the pass is one of the three greatest mountain passes of the Great Wall of China. The other two are Shanhaiguan. Juyongguan Pass has two ` sub-passes,' the other at the north; the southern one is called "Nan" and the northern is called "Badaling". The pass had many different names during former Chinese dynasties. However, the name "Juyongguan" was used by more than three dynasties, it was first used in the Qin Dynasty when Emperor Qinshihuang ordered the building of the Great Wall. Juyongguan pass was connected to the Great Wall in the Northern Dynasties era; the present pass route received much renovation later. It was a important strategic place connecting the inner land and the area near the northern border of China, it was used to defend the ancient city of Beijing.

In the middle of the Juyongguan and Guangou Valley, there is the Cloud Platform gate known as the "Crossing Street Tower". It was built in 1342 during the Yuan Dynasty, made of white marble with a height of 9.5 metres. There were three white pagodas atop the platform, giving it the name of "Crossing Street Tower", they were each destroyed in the transitional period between the late Yuan and early Ming Dynasties. In the early Ming Dynasty, a Buddhist Tai'an Temple hall was built on the platform, it was destroyed in 1702 during the Qing Dynasty. The Yuan era Cloud Platform remains. Around the top of the platform are elements such as stone balustrades and a watch post, they remain in the original Yuan style. On the platform are carvings of Buddhist figures and symbols, as well as Buddhist texts written in six languages and scripts: Sanskrit in Lanydza script, Tibetan script,'Phags-pa script, Old Uyghur script, Tangut script and Chinese characters Tibetan language in Tibetan script Mongolian language in'Phags-pa script Old Uyghur language in Old Uyghur script Tangut language in Tangut script Chinese language in Chinese characters In the middle of the platform's base there is an arched portal - where people, carts and palanquins could pass through.

Many images of people and animals were carved around the portal. Juyongguan railway station Operation Chahar Chinese architecture Great Wall at JuYongGuan — Photo Gallery

Xanth is a fantasy world created by author Piers Anthony for his Xanth series of novels known as The Magic of Xanth. Anthony intended for Xanth to be a trilogy, after the success of the first three books expanded the series to nine books. A devoted fan base persuaded the author to continue writing the series, now open-ended. Anthony has stated that he has kept the series going as long as he has because the Xanth novels are "just about all that publishers want" from him; the fact that the name Xanth resembles the pronunciation of part of the author's name is in itself an unintentional pun, matching the playful tone of the books. As of November 2019, there are 42 novels; each human character in Xanth is born with a unique magical ability, called a talent. With the exception of the curse fiends, the winged centaurs, the child Surprise Golem, these abilities never repeat in individuals throughout the entire history of Xanth Though many talents are limited in scope, the series focuses on individuals with "Magician" caliber abilities.

In addition to the human characters, Xanth is populated by elves, demons, fauns, goblins, harpies, naga, ogres, curse fiends, other fictional beasts. Though introduced as obstacles to the human characters, some individuals from those groups become main characters in books of the series; as the series progresses, some of the half-human species are discovered to have the potential to possess magical talents. The centaurs of the primary centaur community, Centaur Isle, exile any centaurs who demonstrate a magical talent. Goblins and harpies are shown to have the potential to possess half-talents, the complementary half existing in a member of the other species,. Other non-human species are known to possess talents, for example: Sesame Serpent and Claire Voyant. Visitors from other dimensions with talents retain their talents after arriving in Xanth. Geographically, modern Xanth resembles the state of Florida in the United States in shape, but has landmarks that mimic well known geographical features from around the world.

One major example of this is the Gap Chasm, an enormous canyon a mile wide which bisects the country, paralleling the DMZ of the Korean Peninsula. The position of the Chasm could correspond with the Cross Florida Barge Canal, similar to the chasm, is forgotten except for those who stumble upon it; the Gap is guarded by a resident dragon, known as Stanley Steamer, is crossed by means of treacherous bridges. Many of Xanth's other geographical features are puns on those of Florida; the Florida Keys exist, though they are, in Xanth, actual keys. Other punning feature names include the Isle of View, Mount Ever-Rest and the Centaur Aisle created by a magician from the Centaur Isle; the moon is close enough. Plants may bear fruit of all descriptions or they may be carnivorous, making travel in Xanth risky. Xanth has a connection with the normal world, referred to as "Mundania". Although any citizen of Xanth can enter Mundania at any time through an isthmus in the northwest, Mundanes enter the isthmus in Xanth from random geographic locations and time periods throughout history.

In other words, Xanth does not have a fixed time in the mundane world. For example, within the lifetime of a normal citizen of Xanth, an American Mundane from 2012 and an Egyptian Mundane from 3,000 B. C. could both walk across the isthmus. However, Mundanes seem to have trouble finding Xanth on a consistent basis, making any travel to Xanth a somewhat rare occurrence. Despite these seeming difficulties, Xanth was colonized in several waves by groups of invaders and nomads from Mundania over the course of several centuries; the series ties these colonization events to actual historical events on Earth, most notably the Punic wars. First mentioned in Crewel Lye, the Adult Conspiracy is one of the prominent features of the Xanth world. In an interview with Moira Allen, Piers Anthony referred to the "Adult conspiracy to keep interesting things from children" as a literary device "parodying current societal conventions" Nearly all subsequent books contain references to the Conspiracy and its effects those novels in which the main characters are children.

At its core, the Adult Conspiracy seeks to protect children from knowledge that could bring them to great harm. The precise age for entering into the world of adults is age 18, corresponding to the age of majority in most places; the primary principle that inducts children into the Conspiracy is the understanding of the secret of "summoning the stork". In Xanthian terms, "summoning the stork" means to put out a call to summon a stork which will deliver to the couple a child. In Isle o

A slow earthquake is a discontinuous, earthquake-like event that releases energy over a period of hours to months, rather than the seconds to minutes characteristic of a typical earthquake. First detected using long term strain measurements, most slow earthquakes now appear to be accompanied by fluid flow and related tremor, which can be detected and located using seismometer data filtered appropriately; that is, they are quiet compared to a regular earthquake, but not "silent" as described in the past. Slow earthquakes should not be confused with tsunami earthquakes, in which slow rupture velocity produces tsunami out of proportion to the triggering earthquake. In a tsunami earthquake, the rupture propagates along the fault more than usual, but the energy release occurs on a similar timescale to other earthquakes. Earthquakes occur as a consequence of gradual stress increases in a region, once it reaches the maximum stress that the rocks can withstand a rupture generates and the resulting earthquake motion is related to a drop in the shear stress of the system.

Earthquakes generate seismic waves when the rupture in the system occurs, the seismic waves consist of different types of waves that are capable of moving through the Earth like ripples over water. The causes that lead to slow earthquakes have only been theoretically investigated, by the formation of longitudinal shear cracks that were analysed using mathematical models; the different distributions of initial stress, sliding frictional stress, specific fracture energy are all taken into account. If the initial stress minus the sliding frictional stress is low, the specific fracture energy or the strength of the crustal material is high slow earthquakes will occur regularly. In other words, slow earthquakes are caused by a variety of stick-slip and creep processes intermediated between asperity-controlled brittle and ductile fracture. Asperities are tiny protrusions along the faces of fractures, they are best documented from intermediate crustal levels of certain subduction zones, but appear to occur on other types of faults as well, notably strike-slip plate boundaries such as the San Andreas fault and "mega-landslide" normal faults on the flanks of volcanos.

Faulting takes place all over Earth. As of 2013 some of the locations that have been studied for slow earthquakes include: Cascadia, Japan, New Zealand and Alaska; the locations of slow earthquakes can provide new insights into the behavior of normal or fast earthquakes. By observing the location of tremors associated with slow-slip and slow earthquakes, seismologists can determine the extension of the system and estimate future earthquakes in the area of study. Teruyuki Kato identifies various types of slow earthquake: low frequency earthquakes low frequency earthquakes and deep-low-frequency earthquakes slow slip events episodic tremor and slip Low frequency earthquakes are seismic events defined by waveforms with periods far greater than those of ordinary earthquakes and abundantly occur during slow earthquakes. LFEs can be volcanic, semi-volcanic, or tectonic in origin, but only tectonic LFEs or LFEs generated during slow earthquakes are described here. Tectonic LFEs are characterized by low magnitudes and have frequencies peaked between 1 and 3 Hz.

They are the largest constituent of non-volcanic tremor at subduction zones, in some cases are the only constituent. In contrast to ordinary earthquakes, tectonic LFEs occur during long-lived slip events at subduction interfaces called slow slip events; the mechanism responsible for their generation at subduction zones is thrust-sense slip along transitional segments of the plate interface. LFEs are sensitive seismic events which can be triggered by tidal forces as well as propagating waves from distant earthquakes. LFEs have hypocenters located down-dip from the seismogenic zone, the source region of megathrust earthquakes. During SSEs, LFE foci migrate along strike at the subduction interface in concert with the primary shear slip front; the depth occurrence of low frequency earthquakes is in the range of 20–45 kilometers depending on the subduction zone, at shallower depths at strike-slip faults in California. At "warm" subduction zones like the west coast of North America, or sections in eastern Japan this depth corresponds to a transition or transient slip zone between the locked and stable slip intervals of the plate interface.

The transition zone is located at depths coincidental with the continental Mohorovicic discontinuity. At the Cascadia subduction zone, the distribution of LFEs form a surface parallel to intercrustal seismic events, but displaced 5–10 kilometers down-dip, providing evidence that LFEs are generated at the plate interface. Low frequency earthquakes are an active area of research and may be important seismic indicators for higher magnitude earthquakes. Since slow slip events and their corresponding LFE signals have been recorded, none of them have been accompanied by a megathrust earthquake, however, SSEs act to increase the stress in the seismogenic zone by forcing the locked interval between the subducting and overriding plate to accommodate for down-dip movement; some calculations find that the probability of a large earthquake occurring during a slow slip event are 30–100 times greater than background probabilities. Understanding the seismic hazard that LFEs might herald is among the pri