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59-398: Like the related fields of scientific visualization and information visualization geovisualization emphasizes knowledge construction over knowledge storage or information transmission. To do this, geovisualization communicates geospatial information in ways that, when combined with human understanding, allow for data exploration and decision-making processes. Traditional, static maps have

118-473: A Commission on Visualization & Virtual Environments in 1995. Geovisualization is closely related to other visualization fields, such as scientific visualization and information visualization . Owing to its roots in cartography , geovisualization contributes to these other fields by way of the map metaphor, which "has been widely used to visualize non-geographic information in the domains of information visualization and domain knowledge visualization." It

177-399: A Mesh plot of a Porsche 911 model imported from a NASTRAN bulk data file. VisIt can read a limited subset of NASTRAN bulk data files, in general enough to import model geometry for visualization. YF-17 aircraft Plot : The featured image displays plots of a CGNS dataset representing a YF-17 jet aircraft. The dataset consists of an unstructured grid with solution. The image was created by using

236-427: A better understanding of underlying perceptual issues create new opportunities for the scientific visualization community. Rendering is the process of generating an image from a model , by means of computer programs. The model is a description of three-dimensional objects in a strictly defined language or data structure. It would contain geometry, viewpoint, texture , lighting , and shading information. The image

295-408: A corresponding real-world coordinate can be calculated. Several types of functions are available in most GIS and remote sensing software for georeferencing. As the simplest type of two-dimensional curve is a straight line, so the simplest form of coordinate transformation is a linear transformation, the most common type being the affine transformation : Where A-F are constant coefficients set for

354-454: A cuboid with a changing frame of reference to show volume, mass and density data. This section will give a series of examples how scientific visualization can be applied today. Star formation : The featured plot is a Volume plot of the logarithm of gas/dust density in an Enzo star and galaxy simulation. Regions of high density are white while less dense regions are more blue and also more transparent. Gravitational waves : Researchers used

413-516: A few minutes, to network-based groups of computers running for hours, to ongoing simulations that run for months. The scale of events being simulated by computer simulations has far exceeded anything possible (or perhaps even imaginable) using the traditional paper-and-pencil mathematical modeling : over 10 years ago, a desert-battle simulation, of one force invading another, involved the modeling of 66,239 tanks, trucks and other vehicles on simulated terrain around Kuwait , using multiple supercomputers in

472-482: A georeferenced raster GIS file or orthophoto . The term georeferencing has also been used to refer to other types of transformation from general expressions of geographic location ( geocodes ) to coordinate measurements, but most of these other methods are more commonly called geocoding . Because of this ambiguity, Georegistration is preferred by some to refer to the image transformation. Occasionally, this process has been called rubbersheeting , but that term

531-463: A large set of spatio-temporal data related to European forests, allowing the data to be explored by non-experts over the Internet. The report summarizing this effort "uncovers a range of fundamental issues relevant to the broad field of geovisualization and information visualization research". The research team cited the two major problems as the inability of the geovisualizers to convince the foresters of

590-450: A limited exploratory capability; the graphical representations are inextricably linked to the geographical information beneath. GIS and geovisualization allow for more interactive maps; including the ability to explore different layers of the map, to zoom in or out, and to change the visual appearance of the map, usually on a computer display. Geovisualization represents a set of cartographic technologies and practices that take advantage of

649-436: A minimum of six ground control points, and so on. The entered GCPs are rarely perfectly located and are even more rarely perfectly representative of the distortion in the rest of the image, but the algebraic solution, which appears to be a perfect match, masks any error. To avoid this, it is common to create many more than the minimal required set (creating an overdetermined system ), and use least squares regression to derive

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708-418: A particular Universal Transverse Mercator zone. It is thus the extension of the typical task of curve fitting a relationship between two variables to four dimensions. The goal is to have a pair of functions of the form: Such that for every pixel in the image ( x i n , y i n {\displaystyle x_{in},y_{in}} being its column and row number, respectively),

767-453: A potential technique for mapping unearthed archaeological environments as well as for accessing and exploring archaeological data in three dimensions. The implications of geovisualization for archaeology are not limited to advances in archaeological theory and exploration but also include the development of new, collaborative relationships between archaeologists and computer scientists. Geovisualization tools provide multiple stakeholders with

826-521: A pseudocolor plot of the dataset's Mach variable, a Mesh plot of the grid, and Vector plot of a slice through the Velocity field. City rendering : An ESRI shapefile containing a polygonal description of the building footprints was read in and then the polygons were resampled onto a rectilinear grid, which was extruded into the featured cityscape. Inbound traffic measured : This image is a visualization study of inbound traffic measured in billions of bytes on

885-431: A road intersection or the corner of a building. When very high accuracy registration is required, it is common to place or paint high-contrast markers on the ground at survey control monuments before the photography is taken, and use GNSS-measured coordinates for the output. In most software, these are entered by pointing at the location on the image, then pointing at the same location on a vector base map or orthophoto that

944-505: A set of function parameters that most closely matches the points. This is almost never a perfect match, so the variance between each GCP location and the location predicted by the functions can be measured and summarized as a Root-mean-square error (RMSE). A lower RMSE thus means that the transformation formulas closely match the GCPs. Once the function parameters are determined, the transformation functions can be used to transform every pixel of

1003-467: A tool for modeling the environmental interests and policy concerns of the general public. Jiang et al. mention two examples, in which "3D photorealistic representations are used to show urban redevelopment [and] dynamic computer simulations are used to show possible pollution diffusion over the next few years." The widespread use of the Internet by the general public has implications for these collaborative planning efforts, leading to increased participation by

1062-467: A useful part of mathematical modelling of many natural systems in physics, and computational physics, chemistry and biology; human systems in economics, psychology, and social science; and in the process of engineering and new technology, to gain insight into the operation of those systems, or to observe their behavior. The simultaneous visualization and simulation of a system is called visulation . Computer simulations vary from computer programs that run

1121-575: A vector field by using one of the two eigenvectors to represent the tensor each point in the field and then visualized using vector field visualization methods. For 3D scalar fields the primary methods are volume rendering and isosurfaces . Methods for visualizing vector fields include glyphs (graphical icons) such as arrows, streamlines and streaklines , particle tracing, line integral convolution (LIC) and topological methods. Later, visualization techniques such as hyperstreamlines were developed to visualize 2D and 3D tensor fields. Computer animation

1180-510: A visualization such as auxiliary plots, images of experimental data, project logos, etc. Scatter plot : VisIt's Scatter plot allows visualizing multivariate data of up to four dimensions. The Scatter plot takes multiple scalar variables and uses them for different axes in phase space. The different variables are combined to form coordinates in the phase space and they are displayed using glyphs and colored using another scalar variable. Porsche 911 model (NASTRAN model): The featured plot contains

1239-412: Is a digital image or raster graphics image . The term may be by analogy with an "artist's rendering" of a scene. 'Rendering' is also used to describe the process of calculating effects in a video editing file to produce final video output. Important rendering techniques are: Volume rendering is a technique used to display a 2D projection of a 3D discretely sampled data set . A typical 3D data set

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1298-564: Is a 3D interactive fire simulator, bringing sandtable exercises to life. The SimTable uses advanced computer simulations to model fires in any area, including local neighborhoods, utilizing actual slope, terrain, wind speed/direction, vegetation, and other factors. SimTable Models were used in Arizona's largest fire on record, the Wallow Fire . Geovisualizers, working with European foresters, used CommonGIS and Visualization Toolkit ( VTK ) to visualize

1357-555: Is a commonly used sidecar file that specifies these six coefficients for image georeferencing. Higher order polynomial transformations are also commonly used. For example, a Second-order polynomial transformation would be: The second-order terms (and third-order terms in a third-order polynomial) allow for the variable warping of the image, which is especially useful for removing the inherent distortion in aerial photographs. In addition to global parametric formulas, piecewise formulas can also be used, which transform different parts of

1416-399: Is a group of 2D slice images acquired by a CT or MRI scanner. Usually these are acquired in a regular pattern (e.g., one slice every millimeter) and usually have a regular number of image pixels in a regular pattern. This is an example of a regular volumetric grid, with each volume element, or voxel represented by a single value that is obtained by sampling the immediate area surrounding

1475-544: Is a location that can be identified on both the image and the ground, so that it has precise coordinates in both the image coordinate system ( x i n {\displaystyle x_{in}} = pixel column, y i n {\displaystyle y_{in}} = pixel row) and the ground coordinate system ( x o u t , y o u t {\displaystyle x_{out},y_{out}} ). Easily visible locations that be precisely located are preferred as GCP's, such as

1534-405: Is a type of coordinate transformation that binds a digital raster image or vector database that represents a geographic space (usually a scanned map or aerial photograph ) to a spatial reference system , thus locating the digital data in the real world. It is thus the geographic form of image registration or image rectification . The term can refer to the mathematical formulas used to perform

1593-790: Is already in the desired coordinate system. This can then be moved and adjusted to improve accuracy. With a minimal set of GCPs, the known coordinates can be entered into the mathematical equations for the desired type of transformation, which can then be solved using linear algebra to determine the coefficients and derive the formulas to use for the entire grid. For example, the linear affine transformation above has six unknown coefficients, so six equations with known < x i n , y i n , x o u t , y o u t {\displaystyle x_{in},y_{in},x_{out},y_{out}} > are needed to derive them, which will require three ground control points. The second-order polynomial requires

1652-440: Is also referred to as CGI ( Computer-generated imagery or computer-generated imaging), especially when used in films. Applications include medical animation , which is most commonly utilized as an instructional tool for medical professionals or their patients. Computer simulation is a computer program, or network of computers, that attempts to simulate an abstract model of a particular system. Computer simulations have become

1711-490: Is also related to urban simulation . Geovisualization has made inroads in a diverse set of real-world situations calling for the decision-making and knowledge creation processes it can provide. The following list provides a summary of some of these applications as they are discussed in the geovisualization literature. Firefighters have been using sandbox environments to rapidly and physically model topography and fire for wildfire incident command strategic planning. The SimTable

1770-412: Is more commonly applied to a very similar process applied to vector GIS data. The registration of an image to a geographic space is essentially the transformation from an input coordinate system (the inherent coordinates of pixels in the images based on row and column number) to an output coordinate system, a spatial reference system of the user's choice, such as the geographic coordinate system or

1829-555: Is part of the work on the NSF-funded Electronic Visualization Laboratory at the University of Illinois at Chicago. Curve plots : VisIt can plot curves from data read from files and it can be used to extract and plot curve data from higher-dimensional datasets using lineout operators or queries. The curves in the featured image correspond to elevation data along lines drawn on DEM data and were created with

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1888-414: Is the art, technique, and science of creating moving images via the use of computers . It is becoming more common to be created by means of 3D computer graphics , though 2D computer graphics are still widely used for stylistic, low bandwidth, and faster real-time rendering needs. Sometimes the target of the animation is the computer itself, but sometimes the target is another medium , such as film . It

1947-410: Is to graphically illustrate scientific data to enable scientists to understand, illustrate, and glean insight from their data. Research into how people read and misread various types of visualizations is helping to determine what types and features of visualizations are most understandable and effective in conveying information. One of the earliest examples of three-dimensional scientific visualisation

2006-725: The British Army ; and the dot map used by John Snow in 1855 to visualise the Broad Street cholera outbreak . Criteria for classifications: Scientific visualization using computer graphics gained in popularity as graphics matured. Primary applications were scalar fields and vector fields from computer simulations and also measured data. The primary methods for visualizing two-dimensional (2D) scalar fields are color mapping and drawing contour lines . 2D vector fields are visualized using glyphs and streamlines or line integral convolution methods. 2D tensor fields are often resolved to

2065-631: The DoD High Performance Computing Modernization Program . Information visualization is the study of "the visual representation of large-scale collections of non-numerical information, such as files and lines of code in software systems , library and bibliographic databases , networks of relations on the internet , and so forth". Information visualization focused on the creation of approaches for conveying abstract information in intuitive ways. Visual representations and interaction techniques take advantage of

2124-529: The Globus Toolkit to harness the power of multiple supercomputers to simulate the gravitational effects of black-hole collisions. Massive Star Supernovae Explosions : In the image, three-Dimensional Radiation Hydrodynamics Calculations of Massive Star Supernovae Explosions The DJEHUTY stellar evolution code was used to calculate the explosion of SN 1987A model in three dimensions. Molecular rendering : VisIt 's general plotting capabilities were used to create

2183-531: The NSFNET T1 backbone for the month of September 1991. The traffic volume range is depicted from purple (zero bytes) to white (100 billion bytes). It represents data collected by Merit Network, Inc. Important laboratories in the field are: Conferences in this field, ranked by significance in scientific visualization research, are: See further: Computer graphics organizations , Supercomputing facilities Georeference Georeferencing or georegistration

2242-489: The National Science Foundation report a focus on the potential for the use of "dynamic visual displays as prompts for scientific insight and on the methods through which dynamic visual displays might leverage perceptual cognitive processes to facilitate scientific thinking". Geovisualization has continued to grow as a subject of practice and research. The International Cartographic Association (ICA) established

2301-479: The ability of modern microprocessors to render changes to a map in real time, allowing users to adjust the mapped data on the fly. The term visualization is first mentioned in the cartographic literature at least as early as 1953, in an article by University of Chicago geographer Allen K. Philbrick. New developments in the field of computer science prompted the National Science Foundation to redefine

2360-548: The ability to make balanced environmental decisions by taking into account "the complex interacting factors that should be taken into account when studying environmental changes". Geovisualization users can use a georeferenced model to explore a complex set of environmental data, interrogating a number of scenarios or policy options to determine a best fit. Both planners and the general public can use geovisualization to explore real-world environments and model 'what if' scenarios based on spatio-temporal data. While geovisualization in

2419-443: The complex plane are inherently 4-dimensional, but there is no natural geometric projection into lower dimensional visual representations. Instead, colour vision is exploited to capture dimensional information using techniques such as domain coloring . Computer mapping of topographical surfaces : Through computer mapping of topographical surfaces, mathematicians can test theories of how materials will change when stressed. The imaging

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2478-431: The efficacy of geovisualization in their work and the foresters' misgivings over the dataset's accessibility to non-experts engaging in "uncontrolled exploration". While the geovisualizers focused on the ability of geovisualization to aid in knowledge construction, the foresters preferred the information-communication role of more traditional forms of cartographic representation. Geovisualization provides archaeologists with

2537-675: The entire image. These formulas allow an image to be moved (the C and F coefficients specify the desired location of the top left corner of the image), scaled (without rotation, the A and E coefficients specify the size of each cell or spatial resolution ), and rotated . In the last case, if the cell size is r in both the x and y directions, and the image is to be rotated α degrees counter-clockwise, then A = E = r cos ⁡ ( α ) , B = D = r sin ⁡ ( α ) {\displaystyle A=E=r\cos(\alpha ),B=D=r\sin(\alpha )} . The world file developed by Esri

2596-585: The feature lineout capability. Lineout allows you to interactively draw a line, which specifies a path for data extraction. The resulting data was then plotted as curves. Image annotations : The featured plot shows Leaf Area Index (LAI), a measure of global vegetative matter, from a NetCDF dataset. The primary plot is the large plot at the bottom, which shows the LAI for the whole world. The plots on top are actually annotations that contain images generated earlier. Image annotations can be used to include material that enhances

2655-503: The forming of mental models. Higher-dimensional objects can be visualized in form of projections (views) in lower dimensions. In particular, 4-dimensional objects are visualized by means of projection in three dimensions. The lower-dimensional projections of higher-dimensional objects can be used for purposes of virtual object manipulation, allowing 3D objects to be manipulated by operations performed in 2D, and 4D objects by interactions performed in 3D. In complex analysis , functions of

2714-497: The human eye's broad bandwidth pathway into the mind to allow users to see, explore, and understand large amounts of information at once. The key difference between scientific visualization and information visualization is that information visualization is often applied to data that is not generated by scientific inquiry. Some examples are graphical representations of data for business, government, news and social media. Interface technology and perception shows how new interfaces and

2773-454: The image in different ways. A common example is a Thin plate spline transformation. It is very rare that a user would specify the parameters for the transformation directly. Instead, most GIS and remote sensing software provides an interactive environment for visually aligning the image to the destination coordinate system. The most common method for doing this is to create a series of ground control points (GCP). A ground control point

2832-419: The image to its real-world location. Two options are usually available for making this transformation permanent. One option is to save the parameters themselves as a form of metadata , either in the header of the image file itself (e.g., GeoTIFF ), or in a sidecar file stored alongside the image file (e.g., a world file ). With this metadata, the software can perform the transformation dynamically as it displays

2891-444: The image, so that it appears to align with other data in the desired coordinate system. The alternative method is rectification , in which the image is resampled to create a new raster grid that is natively tied to the coordinate system. Rectification was traditionally the only option, until the computing power became available for the intense calculations of dynamic coordinate transformations; even now, drawing and analysis performance

2950-549: The molecular rendering shown in the featured visualization. The original data was taken from the Protein Data Bank and turned into a VTK file before rendering. Terrain visualization : VisIt can read several file formats common in the field of Geographic Information Systems (GIS), allowing one to plot raster data such as terrain data in visualizations. The featured image shows a plot of a DEM dataset containing mountainous areas near Dunsmuir, CA. Elevation lines are added to

3009-559: The plot to help delineate changes in elevation. Tornado Simulation : This image was created from data generated by a tornado simulation calculated on NCSA's IBM p690 computing cluster. High-definition television animations of the storm produced at NCSA were included in an episode of the PBS television series NOVA called "Hunt for the Supertwister." The tornado is shown by spheres that are colored according to pressure; orange and blue tubes represent

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3068-422: The preceding fields may be divided into two separate domains—the private domain, in which professionals use geovisualization to explore data and generate hypotheses, and the public domain, in which these professionals present their "visual thinking" to the general public—planning relies more heavily than many other fields on collaboration between the general public and professionals. Planners use geovisualization as

3127-409: The process typically involves identifying a sample of several ground control points ( GCPs ) with known locations on the image and the ground, then using curve fitting techniques to generate a parametric (or piecewise parametric) formula to transform the rest of the image. Once the parameters of the formula are stored, the image may be transformed dynamically at drawing time, or resampled to generate

3186-444: The public while decreasing the amount of time it takes to debate more controversial planning decisions. Scientific visualization Scientific visualization ( also spelled scientific visualisation ) is an interdisciplinary branch of science concerned with the visualization of scientific phenomena. It is also considered a subset of computer graphics , a branch of computer science. The purpose of scientific visualization

3245-684: The rising and falling airflow around the tornado. Climate visualization : This visualization depicts the carbon dioxide from various sources that are advected individually as tracers in the atmosphere model. Carbon dioxide from the ocean is shown as plumes during February 1900. Atmospheric Anomaly in Times Square In the image the results from the SAMRAI simulation framework of an atmospheric anomaly in and around Times Square are visualized. Scientific visualization of mathematical structures has been undertaken for purposes of building intuition and for aiding

3304-524: The term in a 1987 report which placed visualization at the convergence of computer graphics, image processing, computer vision, computer-aided design, signal processing, and user interface studies and emphasized both the knowledge creation and hypothesis generation aspects of scientific visualization. Geovisualization developed as a field of research in the early 1980s, based largely on the work of French graphic theorist Jacques Bertin . Bertin's work on cartographic design and information visualization share with

3363-448: The transformation, the metadata stored alongside or within the image file to specify the transformation, or the process of manually or automatically aligning the image to the real world to create such metadata. The most common result is that the image can be visually and analytically integrated with other geographic data in geographic information systems and remote sensing software. A number of mathematical methods are available, but

3422-734: The voxel. According to Rosenblum (1994) "volume visualization examines a set of techniques that allows viewing an object without mathematically representing the other surface. Initially used in medical imaging , volume visualization has become an essential technique for many sciences, portraying phenomena become an essential technique such as clouds, water flows, and molecular and biological structure. Many volume visualization algorithms are computationally expensive and demand large data storage. Advances in hardware and software are generalizing volume visualization as well as real time performances". Developments of web-based technologies, and in-browser rendering have allowed of simple volumetric presentation of

3481-432: Was Maxwell's thermodynamic surface , sculpted in clay in 1874 by James Clerk Maxwell . This prefigured modern scientific visualization techniques that use computer graphics . Notable early two-dimensional examples include the flow map of Napoleon's March on Moscow produced by Charles Joseph Minard in 1869; the "coxcombs" used by Florence Nightingale in 1857 as part of a campaign to improve sanitary conditions in

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