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Métricas de evaluación y función de error Pixel accuracyPixel accuracy

2 Estado del arte

4.3 Arquitecturas de redes neuronales para detección de objetos

4.4.4.1 Métricas de evaluación y función de error Pixel accuracyPixel accuracy

While evidence of human activity in Mesoamerica dates back to at least 8000 years b.c.e., it was not until around 1500 b.c.e. that the most signifi cant early center of culture arose in Central America with the Olmec. Th is early culture set the stage by establishing the artistic production that all subse- quent cultures would follow. Monumental sculpture, portrai- ture, images of supernatural deities, and semiprecious stone objects were the key art forms developed by the Olmec and shared by all ancient Mesoamerican cultures.

Th e Olmec culture developed along the Gulf Coast of Mexico around 1500 b.c.e. Sometimes referred to as the “mother culture” of Mesoamerica, the Olmec developed many of the crucial stylistic elements that become charac- teristic of Mesoamerican art. Th e earliest Olmec site is San Lorenzo, a complex, man-made center of civilization estab- lished south of what is now Veracruz, Mexico, in the Early Preclassic Period (1500–1200 b.c.e.) Signifi cantly, the well- known monumental stone colossal heads were created here. Th ese giant heads are entirely three-dimensional (sculpted in the round). Th ey probably depict important Olmec rulers and provide early evidence of portraiture. While the heads share many similar features (deep-set eyes, wide nose, full lips), they are also each slightly diff erent.

Th e second most signifi cant Olmec site is La Venta, near the border of what are now the Mexican states of Tabasco and Veracruz. Founded during the Middle Preclassic Pe- riod (1200–400 b.c.e.), La Venta also produced impressive examples of monumental art. In addition to colossal heads, there are large stone altars that actually functioned as ruler thrones. Th ese thrones depict a ruler seated in a niche con-

nected to a rope attached to captives who are carved in relief on the sides of the object. Th is imagery probably indicates the ruler’s earthly and supernatural powers.

Also of note is the appearance of the stela form of monu- mental sculpture, where a large stone slab is decorated with relief carvings to commemorate an event or person. Relief carvings are created by cutting a design into stone and then removing the background to make the design stand out. Oft en depicting rulers, deities, or both, stelae became one of the most distinguishing art forms in Mesoamerica. Stelae functioned as records of events and have provided signifi cant informa- tion concerning Mesoamerican history, society, and religion. Th e Olmec carved smaller objects in the form of supernatural beings in jade and greenstone. One example is the werejaguar, a supernatural fi gure marked by its almond-shaped eyes, upturned lip, pug nose, and cleft head. Th e features of the werejaguar reappear throughout Mesoamerican art.

Other unique artistic developments are found outside the Olmec center. Highly naturalistic male and female fi g- urines were made at Xochipala (in modern-day Guerrero) and Tlatilco (north of Mexico City) and lifelike ceramic baby fi gures at Las Bocas (in central Mexico). Cave painting also began during the Middle Preclassic Period. One exam- ple found at Oxtotitlan depicts a ruler in the guise of a bird deity. While Olmec cultural production was varied, a clear emphasis was placed on rulers and supernatural beings. De- spite the dominance of the Olmec for many centuries, the culture eventually collapsed sometime before 100 b.c.e. for reasons still unknown.

Th e Zapotec culture arose within the Oaxaca valley re- gion during the Late Preclassic Period (400 b.c.e.–150 c.e.). A key Zapotec site, Monte Albán, features impressive exam- ples of monumental architecture and art. Of particular im- portance is the Temple of the Danzantes, which is named for its numerous incised stone slabs featuring dancing fi gures. Th e dancers are male captives who bear physical evidence of their captors’ power and brutality; they all have their eyes closed, symbolizing their death, and are stripped nude as a form of humiliation. Each dancer also has a scrolling motif emanating from the genital area as a sign of mutilation. Giv- en the abundance of dancers (numbering at least 300), the Zapotec rulers clearly wished to express their dominance and power, but not all of their art production focused on such issues. Th e Zapotec also created ceramic and jade ob- jects that demonstrate the infl uence of the Olmec. Indeed, pieces of Olmec jade have been found at Monte Albán and throughout later sites, providing further evidence of the Olmec’s prestige and infl uence.

An entirely diff erent artistic tradition developed in west- ern Mexico during the Late Preclassic. Unaff ected by activi- ties taking place elsewhere in Mesoamerica, the cultures of western Mexico produced a style of ceramics unlike any oth- er. In Colima unique ceramic vessels in the shape of hairless dogs were created. Oft en wearing human masks, the Colima dogs display an unusually high degree of charm and natu-

ralism. Th e Nayarit engaged in an entirely diff erent form of ceramics, creating unusual scenes of human fi gures placed in architectural settings. From ball courts to domestic houses, the Nayarit ceramic scenes provide an unprecedented view of daily life in Mesoamerica. Th is area is known for their un- usual, nonfunctional ceramic art works, which was their pri- mary form of artistic production.

Many important cultural developments of the early Maya also occurred during the Late Preclassic Period—in the high- lands of Chiapas, Mexico, and Guatemala; along the Caribbe- an coast; and in the Petén region of northern Guatemala. Th e highland sites of Izapa in Chiapas and Kaminaljuyú in what is now Guatemala City produced objects that bear the mark of Olmec infl uence, but they developed stylistic programs all their own. Th e importance of stelae as markers of rulers, dei- ties, and events evolved with the development of glyphs and an iconographic, or symbolic, program. Images on early Maya stelae primarily emphasize the mythical and supernatural (such as the water god Chaak, the mythical World Tree, and the bird deity), though ruler stelae do appear at Kaminaljuyú. Th ese stylistic developments set the stage for the Maya to be- come one of the most sophisticated cultures in the world.

Th e most important and infl uential center of civilization in all of ancient Mesoamerica was Teotihuacán. Located in the Valley of Mexico, it became a powerful urban center of com- merce and cultural activity during the Early Classic Period (150–650 c.e.). At its height it is estimated that the city’s pop- ulation reached as high as 125,000 inhabitants. Teotihuacá- nos expanded upon the existing pantheon of Mesoamerican gods to develop a synthesized and complex visual program. Th is culture produced monumental art and architecture as well as ceramics, ceremonial and burial objects (like censers, adornments, and fi gurines), and intricate masks. Many mon- umental stone sculptures were created at Teotihuacán, such as a large depiction of Chalchiuhtlicue (the water goddess, also called the Great Goddess, an important deity in this cul- ture). Not all of the sculpture produced at Teotihuacán was monumental in size. Many extraordinarily detailed fi gurines in various poses have been found. Also large, brightly colored ceramic urns with human and animal elements were created from mass-produced elements. Numerous beautiful death masks have been found at Teotihuacán, which demonstrate an emphasis on craft smanship.

Caves and mountains were essential components of Teo- tihuacán’s religion, because it was from these locations that water fl owed and life was generated. Th is concept informed much of the art produced there, particularly with respect to the prevalence of the Great Goddess. Th e most unusual and striking contributions made by Teotihuacános to the history of art were their advancements in mural painting. Brightly painted and intricate murals would have decorated the walls of Teotihuacán’s buildings. Many of these murals seem in- structive, in that they depict processional scenes of fi gures in profi le carrying ceremonial implements like incense bags and maguey spines for bloodletting. Th e only fi gures that were de-

picted frontally were gods. Th e most well-known example of this may be seen in the murals in the Tepantitla apartment complex: Th e Great Goddess is portrayed amid an abundance of water and plants, which she brings to the people. From her head grow plants and insects. She is fl anked by two fi gures in profi le that make off erings to the goddess. Below the Great Goddess fl ows water from a mountain that carries many small fi gures with speech scrolls fl owing from their mouths, presumably out of happiness. Clearly, the emphasis in this mural is on life and abundance.