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Photoclinometry
Photoclinometry, or shape-from-shading, is the process by which a 2-dimensional image of a surface is transformed into a surface map that represents different levels of elevation. It uses the shadows and light direction as reference points. It is used mostly to depict the surface of sculptures, to give an idea of how it would look in 3-dimensions. The techniques depend on very specific conditions, especially light direction. The process When light bounces off an object, it reflects with location-specific brightness that depends on the shape of the object and the position of the lightning source. This reflection map can be used to create a bump map of a surface, which uses grayscale levels to depict the height of a point on a surface. Knowing the direction and angle of the light source, one can calculate the approximate height that a point has. However, the light direction and angle is usually unknown, which leads to poor quality images, or having to create multiple bump maps, each ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometric Stereo
Photometric stereo is a technique in computer vision for estimating the surface normals of objects by observing that object under different lighting conditions. It is based on the fact that the amount of light reflected by a surface is dependent on the orientation of the surface in relation to the light source and the observer. By measuring the amount of light reflected into a camera, the space of possible surface orientations is limited. Given enough light sources from different angles, the surface orientation may be constrained to a single orientation or even overconstrained. The technique was originally introduced by Woodham in 1980.Woodham, R.J. 1980Photometric method for determining surface orientation from multiple images Optical Engineerings 19, I, 139-144. The special case where the data is a single image is known as shape from shading, and was analyzed by B. K. P. Horn in 1989.B. K. P. Horn, 1989. Obtaining shape from shading information. In B. K. P. Horn and M. J. Broo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometric Stereo
Photometric stereo is a technique in computer vision for estimating the surface normals of objects by observing that object under different lighting conditions. It is based on the fact that the amount of light reflected by a surface is dependent on the orientation of the surface in relation to the light source and the observer. By measuring the amount of light reflected into a camera, the space of possible surface orientations is limited. Given enough light sources from different angles, the surface orientation may be constrained to a single orientation or even overconstrained. The technique was originally introduced by Woodham in 1980.Woodham, R.J. 1980Photometric method for determining surface orientation from multiple images Optical Engineerings 19, I, 139-144. The special case where the data is a single image is known as shape from shading, and was analyzed by B. K. P. Horn in 1989.B. K. P. Horn, 1989. Obtaining shape from shading information. In B. K. P. Horn and M. J. Broo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photogrammetry
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena. The term photogrammetry was coined by the Prussian architect Albrecht Meydenbauer, which appeared in his 1867 article "Die Photometrographie." There are many variants of photogrammetry. One example is the extraction of three-dimensional measurements from two-dimensional data (i.e. images); for example, the distance between two points that lie on a plane parallel to the photographic image plane can be determined by measuring their distance on the image, if the scale (map), scale of the image is known. Another is the extraction of accurate color ranges and values representing such quantities as albedo, specular reflection, Metallicity#Photometric colors, metallicity, or ambient occlusion from photographs of mater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bump Map
Bump mapping is a texture mapping technique in computer graphics for simulating bumps and wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the object and using the perturbed normal during lighting calculations. The result is an apparently bumpy surface rather than a smooth surface although the surface of the underlying object is not changed. Bump mapping was introduced by James Blinn in 1978.Blinn, James F"Simulation of Wrinkled Surfaces" Computer Graphics, Vol. 12 (3), pp. 286-292 SIGGRAPH-ACM (August 1978) Normal mapping is the most common variation of bump mapping used. Principles Bump mapping is a technique in computer graphics to make a rendered surface look more realistic by simulating small displacements of the surface. However, unlike displacement mapping, the surface geometry is not modified. Instead only the surface normal is modified ''as if'' the surface had been displaced. The modified surface normal is then used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grayscale
In digital photography, computer-generated imagery, and colorimetry, a grayscale image is one in which the value of each pixel is a single sample representing only an ''amount'' of light; that is, it carries only intensity information. Grayscale images, a kind of black-and-white or gray monochrome, are composed exclusively of shades of gray. The contrast ranges from black at the weakest intensity to white at the strongest. Grayscale images are distinct from one-bit bi-tonal black-and-white images, which, in the context of computer imaging, are images with only two colors: black and white (also called ''bilevel'' or '' binary images''). Grayscale images have many shades of gray in between. Grayscale images can be the result of measuring the intensity of light at each pixel according to a particular weighted combination of frequencies (or wavelengths), and in such cases they are monochromatic proper when only a single frequency (in practice, a narrow band of frequencies) is ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, although backgrounds in physics, chemistry, biology, and other sciences are also useful. Field research (field work) is an important component of geology, although many subdisciplines incorporate laboratory and digitalized work. Geologists can be classified in a larger group of scientists, called geoscientists. Geologists work in the energy and mining sectors searching for natural resources such as petroleum, natural gas, precious and base metals. They are also in the forefront of preventing and mitigating damage from natural hazards and disasters such as earthquakes, volcanoes, tsunamis and landslides. Their studies are used to warn the general public of the occurrence of these events. Geologists are also important contributors to climate ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Science
Planetary science (or more rarely, planetology) is the scientific study of planets (including Earth), celestial bodies (such as moons, asteroids, comets) and planetary systems (in particular those of the Solar System) and the processes of their formation. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, which originally grew from astronomy and Earth science, and now incorporates many disciplines, including planetary geology, cosmochemistry, atmospheric science, physics, oceanography, hydrology, theoretical planetary science, glaciology, and exoplanetology. Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology. There are interrelated observational and theoretical branches of planetary science. Observational research can involve combinations of spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topographic Maps
In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but historically using a variety of methods. Traditional definitions require a topographic map to show both natural and artificial features. A topographic survey is typically based upon a systematic observation and published as a map series, made up of two or more map sheets that combine to form the whole map. A topographic map series uses a common specification that includes the range of cartographic symbols employed, as well as a standard geodetic framework that defines the map projection, coordinate system, ellipsoid and geodetic datum. Official topographic maps also adopt a national grid referencing system. Natural Resources Canada provides this description of topographic maps: Other authors define topographic maps by contrasting them with anoth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Elevation Model
A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, moon, or asteroid. A "global DEM" refers to a discrete global grid. DEMs are used often in geographic information systems (GIS), and are the most common basis for digitally produced relief maps. A digital terrain model (DTM) represents specifically the ground surface while DEM and DSM may represent tree top canopy or building roofs. While a DSM may be useful for landscape modeling, city modeling and visualization applications, a DTM is often required for flood or drainage modeling, land-use studies, geological applications, and other applications, and in planetary science. Terminology There is no universal usage of the terms ''digital elevation model'' (DEM), ''digital terrain model'' (DTM) and ''digital surface model'' (DSM) in scientific literature. In most cases the term ''digital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereoscopy
Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives . Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope. Most stereoscopic methods present a pair of two-dimensional images to the viewer. The left image is presented to the left eye and the right image is presented to the right eye. When viewed, the human brain perceives the images as a single 3D view, giving the viewer the perception of 3D depth. However, the 3D effect lacks proper focal depth, which gives rise to the Vergence-Accommodation Conflict. Stereoscopy is distinguished from other types of 3D displays that display an image in three full dimensions, allowing the observer to increase information about the 3-dimensional objects being displayed by head and eye mov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars Reconnaissance Orbiter
''Mars Reconnaissance Orbiter'' (MRO) is a spacecraft designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and relay data from surface missions back to Earth. It was launched on August 12, 2005, and reached Mars on March 10, 2006. In November 2006, after five months of aerobraking, it entered its final science orbit and began its primary science phase. The cost to develop and operate MRO through the end of its prime mission in 2010 was . The spacecraft continues to operate at Mars, far beyond its intended design life. Due to its critical role as a high-speed data-relay for ground missions, NASA intends to continue the mission as long as possible, at least through the late 2020s. Pre-launch After the twin failures of the ''Mars Climate Orbiter'' and the Mars Polar Lander missions in 1999, NASA reorganized and replanned its Mars Exploration Program. In October 2000, NASA announced its reformulated Mars plans, which reduced the numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereoscopy
Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives . Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope. Most stereoscopic methods present a pair of two-dimensional images to the viewer. The left image is presented to the left eye and the right image is presented to the right eye. When viewed, the human brain perceives the images as a single 3D view, giving the viewer the perception of 3D depth. However, the 3D effect lacks proper focal depth, which gives rise to the Vergence-Accommodation Conflict. Stereoscopy is distinguished from other types of 3D displays that display an image in three full dimensions, allowing the observer to increase information about the 3-dimensional objects being displayed by head and eye mov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
