What is relief(地勢)?999急!!!!!!!!!!!!!!!!!!!!!!!

A relief is a sculptured artwork where a modeled form projects out from a flat background.

Reliefs are a common type of artwork found throughout the world, particularly to decorate monumental buildings, such as temples. The frieze in the classical Corinthian order is often enriched with bas-relief (low relief). Alto-relievo (high-relief) may been seen in the pediments of classical temples, e.g. the Parthenon. Reliefs can be used for a single scene, or ordered into a narrative. They can be very detailed to the extent that even tensed musculature itself may be seen.

Types of relief

Several types of relief are commonly used and defined although in all cases the images must attach to the background..

Bas-relief (pronounced "bah"), or low relief, with the background compressed for depth; as seen for example in numismatics. Although unusual, Bas-relief may show faces and even bodies in natural relief.
Alto-relievo, or high relief, where the image is highly undercut and rendered almost in the round against its flat background. In alto-relief the figures are usually near natural depth and the background is more detailed and deeper.
Sunken-relief, also known as intaglio or hollow-relief, where the image is carved into the stone, creating in effect a negative, in contrast to other types of relief work where the surrounding stone is carved away to leave the image.

Terrain, or relief, is the third or vertical dimension of land surface. When relief is described underwater, the term bathymetry is used. Topography has recently become an additional synonym, though in many parts of the world it retains it original more general meaning of description of place.

Terrain is used as a general term in geography, especially physical geography, referring to the lie of the land. This is usually expressed in terms of the elevation, slope, and orientation of terrain features. Terrain affects surface water flow and distribution. Over a large area, it can affect weather and climate patterns.

Contents [hide]
1 Importance of terrain
2 Characteristics of Terrain
3 Geomorphology
4 See also



[edit] Importance of terrain
The understanding of terrain is critical for a number of reasons.

The terrain of a region largely determines its suitability for human settlement: flatter, alluvial plains tend to be better farming soils than steeper, rockier uplands.
In terms of environmental quality, agriculture, and hydrology, understanding the terrain of an area enables the understanding of watershed boundaries, drainage characteristics, water movement, and impacts on water quality. Complex arrays of relief data are used as input parameters for hydrology transport models (such as the SWMM or DSSAM Models) to allow prediction of river water quality.
Understanding terrain also supports on soil conservation, especially in agriculture. Contour plowing is an established practice enabling sustainable agriculture on sloping land; it is the practice of plowing along lines of equal elevation instead of upand down a slope.
Terrain is militarily critical because it determines the ability of armed forces to take and hold areas, and to move troops and material into and through areas. An understanding of terrain is basic to both defensive and offensive strategy.
Terrain is important in determining weather patterns. Two areas close to each other geographically may differ radically in precipitation levels or timing because of elevation differences or a "rain shadow" effect.

[edit] Characteristics of Terrain
Land surface is, by its nature, fractal, anisotropic and non-periodic. This means that similar shapes and properties of land surface can be observed at various scales and in various directions. Land surface can be rather smooth but also very rough and dissected and complex. Areas of land surface that have relatively homogeneous morphometric properties are called landforms.Terrain is stupid and boring.


[edit] Geomorphology
Geomorphology is in large part the study of the formation of terrain or topography. Terrain is formed by intersecting processes:

Geological processes: migration of tectonic plates, faulting and faulting, volcanic eruptions)
Erosional processes: water and wind erosion, landslides
Extra-terrestrial: falls of meteors.
Tectonic processes such as orogenies cause land to be elevated, and erosional (and weathering) processes cause land to be worn away to lower elevations..

Land surface parameters are quantitative measures of various morphometric properties of a surface. The most common examples are derivatives in different directions, which can the used to derive slope or aspect of a terrain or curvatures at each location. DLSM can also be used to derive hydrological parameters that reflect flow/erosion processes and climatic LSPs based on the modelling of solar radiation or air flow.

Land surface objects are definite physical objects (lines, points, areas) that differ from the surrounding objects. The most typical examples are lines of watersheds, stream networks, ridges, break-lines, pools, borders of specific landforms etc. Each land surface object can also be quantified with various properties.