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52-455: ArcMap users can create and manipulate data sets to include a variety of information. For example, the maps produced in ArcMap generally include features such as north arrows, scale bars, titles, legends, neat lines, etc. The software package includes a style-set of these features. As well as the ability to upload numerous other reference styles to apply to any mapping function. The ArcGIS suite

104-468: 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,

156-495: A three-dimensional representation of geometric data (often Cartesian ) that is stored in the computer for the purposes of performing calculations and rendering digital images , usually 2D images but sometimes 3D images . The resulting images may be stored for viewing later (possibly as an animation ) or displayed in real time . 3-D computer graphics, contrary to what the name suggests, are most often displayed on two-dimensional displays. Unlike 3D film and similar techniques,

208-495: A 3D model is formed from points called vertices that define the shape and form polygons . A polygon is an area formed from at least three vertices (a triangle). A polygon of n points is an n-gon. The overall integrity of the model and its suitability to use in animation depend on the structure of the polygons. Before rendering into an image, objects must be laid out in a 3D scene . This defines spatial relationships between objects, including location and size . Animation refers to

260-453: A DSM, the digital terrain model (DTM) represents the bare ground surface without any objects like plants and buildings (see the figure on the right). DEM is often used as a generic term for DSMs and DTMs, only representing height information without any further definition about the surface. Other definitions equalise the terms DEM and DTM, equalise the terms DEM and DSM, define the DEM as

312-445: A DTM is often required for flood or drainage modeling, land-use studies , geological applications, and other applications, and in planetary science . 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 surface model represents the earth's surface and includes all objects on it. In contrast to

364-539: A digital elevation map tens of kilometers on a side with a resolution of around ten meters. Other kinds of stereoscopic pairs can be employed using the digital image correlation method, where two optical images are acquired with different angles taken from the same pass of an airplane or an Earth Observation Satellite (such as the HRS instrument of SPOT5 or the VNIR band of ASTER ). The SPOT 1 satellite (1986) provided

416-534: A human face and a hand that had originally appeared in the 1971 experimental short A Computer Animated Hand , created by University of Utah students Edwin Catmull and Fred Parke . 3-D computer graphics software began appearing for home computers in the late 1970s. The earliest known example is 3D Art Graphics , a set of 3-D computer graphics effects, written by Kazumasa Mitazawa and released in June 1978 for

468-471: A map. This is the view where the placement of the essential map elements are inserted, such as the north arrow, scale bar, etc. While in this view the user also has control of the data frame just as they would in the Data View, but is mainly concerned with the page space and formatting of spacing. If multiple Data Frames are used they can be combined while in the layout view to fit onto one single page. This

520-472: A matrix of numbers, but the data from a DEM is often rendered in visual form to make it understandable to humans. This visualization may be in the form of a contoured topographic map , or could use shading and false color assignment (or "pseudo-color") to render elevations as colors (for example, using green for the lowest elevations, shading to red, with white for the highest elevation.). Visualizations are sometimes also done as oblique views, reconstructing

572-527: A number of ways, but they frequently use remote sensing rather than direct survey data. Older methods of generating DEMs often involve interpolating digital contour maps that may have been produced by direct survey of the land surface. This method is still used in mountain areas, where interferometry is not always satisfactory. Note that contour line data or any other sampled elevation datasets (by GPS or ground survey) are not DEMs, but may be considered digital terrain models. A DEM implies that elevation

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624-720: A product of national lidar dataset programs. Free DEMs are also available for Mars : the MEGDR, or Mission Experiment Gridded Data Record, from the Mars Global Surveyor 's Mars Orbiter Laser Altimeter (MOLA) instrument; and NASA's Mars Digital Terrain Model (DTM). OpenTopography is a web based community resource for access to high-resolution, Earth science-oriented, topography data (lidar and DEM data), and processing tools running on commodity and high performance compute system along with educational resources. OpenTopography

676-475: A second look is taken what is seen is two distinct sections of ArcMap. The data frame where information is spatial and the table of contents where data is aligned in terms of importance symbology is changed. The section of ArcMap where data is spatially applied from the table of contents. The data comes in feature, rasters, and layers. While working in the spatial sector of the data, ground units (miles, kilometers, feet, meters, etc...) are used and represented in

728-509: A subset of the DTM, which also represents other morphological elements, or define a DEM as a rectangular grid and a DTM as a three-dimensional model ( TIN ). Most of the data providers ( USGS , ERSDAC , CGIAR , Spot Image ) use the term DEM as a generic term for DSMs and DTMs. Some datasets such as SRTM or the ASTER GDEM are originally DSMs, although in forested areas, SRTM reaches into

780-405: A synthetic visual image of the terrain as it would appear looking down at an angle. In these oblique visualizations, elevations are sometimes scaled using " vertical exaggeration " in order to make subtle elevation differences more noticeable. Some scientists, however, object to vertical exaggeration as misleading the viewer about the true landscape. Mappers may prepare digital elevation models in

832-570: A vector-based triangular irregular network (TIN). The TIN DEM dataset is also referred to as a primary (measured) DEM, whereas the Raster DEM is referred to as a secondary (computed) DEM. The DEM could be acquired through techniques such as photogrammetry , lidar , IfSAR or InSAR , land surveying , etc. (Li et al. 2005). DEMs are commonly built using data collected using remote sensing techniques, but they may also be built from land surveying. The digital elevation model itself consists of

884-456: Is a mathematical representation of any three-dimensional object; a model is not technically a graphic until it is displayed. A model can be displayed visually as a two-dimensional image through a process called 3-D rendering , or it can be used in non-graphical computer simulations and calculations. With 3-D printing , models are rendered into an actual 3-D physical representation of themselves, with some limitations as to how accurately

936-426: Is a class of 3-D computer graphics software used to produce 3-D models. Individual programs of this class are called modeling applications or modelers. 3-D modeling starts by describing 3 display models : Drawing Points, Drawing Lines and Drawing triangles and other Polygonal patches. 3-D modelers allow users to create and alter models via their 3-D mesh . Users can add, subtract, stretch and otherwise change

988-602: Is available at four license levels: Basic, Standard, or Advanced (formerly ArcView, ArcEditor, or ArcInfo), and Pro. Each step up in the license provides the user with more extensions that allow a variety of querying to be performed on a data set. Pro is the highest level of licensing, and allows the user to use such extensions as 3D Analyst, Spatial Analyst, and the Geostatistical Analyst as well as numerous new functionalities at each new release. The layout of ArcMap may seem overwhelming at first glance, but when

1040-453: Is available continuously at each location in the study area. One powerful technique for generating digital elevation models is interferometric synthetic aperture radar where two passes of a radar satellite (such as RADARSAT-1 or TerraSAR-X or Cosmo SkyMed ), or a single pass if the satellite is equipped with two antennas (like the SRTM instrumentation), collect sufficient data to generate

1092-897: Is based at the San Diego Supercomputer Center at the University of California San Diego and is operated in collaboration with colleagues in the School of Earth and Space Exploration at Arizona State University and UNAVCO. Core operational support for OpenTopography comes from the National Science Foundation, Division of Earth Sciences. The OpenDemSearcher is a Mapclient with a visualization of regions with free available middle and high resolution DEMs. 3D computer graphics 3D computer graphics , sometimes called CGI , 3-D-CGI or three-dimensional computer graphics , are graphics that use

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1144-621: Is between 50 and 500 meters. In gravimetry e.g., the primary grid may be 50 m, but is switched to 100 or 500 meters in distances of about 5 or 10 kilometers. Since 2002, the HRS instrument on SPOT 5 has acquired over 100 million square kilometers of stereo pairs used to produce a DTED2 format DEM (with a 30-meter posting) DEM format DTED2 over 50 million km . The radar satellite RADARSAT-2 has been used by MacDonald, Dettwiler and Associates Ltd. to provide DEMs for commercial and military customers. In 2014, acquisitions from radar satellites TerraSAR-X and TanDEM-X will be available in

1196-499: Is combined, a truly global relief model is obtained. The SRTM30Plus dataset (used in NASA World Wind ) attempts to combine GTOPO30, SRTM and bathymetric data to produce a truly global elevation model. The Earth2014 global topography and relief model provides layered topography grids at 1 arc-minute resolution. Other than SRTM30plus, Earth2014 provides information on ice-sheet heights and bedrock (that is, topography below

1248-506: Is free to download non-commercially and through the developer's website at a cost commercially. An alternative free global DEM is called GTOPO30 (30 arcsecond resolution , c. 1  km along the equator) is available, but its quality is variable and in some areas it is very poor. A much higher quality DEM from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument of

1300-521: Is if the data used in the map is not in the same location as the previous time it was opened there will be an error. This assists with keeping the file small and reduces the amount of redundancy in data management. There are three main printing techniques and one multipage technique. The multipage technique can be found in a help page on ESRIs website. Temporal Analyst is an extension for storage, management, processing, plotting and analysis of virtually any time-related data inside ArcGIS application and

1352-530: Is the geographic view of the data a user imports. The user can explore, display, and query data and edit files if the correct extensions are owned. The bulk of geographic processing will happen while in this view, such as symbology, import of data, editing, coordinate system definition. Only one Data Frame can be viewed at a time while in this view. ArcMap is run using primarily Shape Files and in more recent versions Geodatabases can be used to store larger sets of data. These file formats are what are uploaded into

1404-501: Is the morphology presented (relative accuracy). Quality assessment of DEM can be performed by comparison of DEMs from different sources. Several factors play an important role for quality of DEM-derived products: Common uses of DEMs include: Released at the beginning of 2022, FABDEM offers a bare earth simulation of the Earth's surface at 30 arc-second resolution. Adapted from GLO-30, the data removes all forests and buildings. The data

1456-406: Is to stay with drawing order as described above. Views are put into place to allow a user to choose between either data view or the layout view. To choose between these views there are two buttons in the bottom left of the data frame to choose from. Navigating through the menus is another option, View > Layout View or View > Data View. The purpose of layout view is for the final design of

1508-1076: Is usually performed using 3-D computer graphics software or a 3-D graphics API . Altering the scene into a suitable form for rendering also involves 3-D projection , which displays a three-dimensional image in two dimensions. Although 3-D modeling and CAD software may perform 3-D rendering as well (e.g., Autodesk 3ds Max or Blender ), exclusive 3-D rendering software also exists (e.g., OTOY's Octane Rendering Engine , Maxon's Redshift) 3-D computer graphics software produces computer-generated imagery (CGI) through 3-D modeling and 3-D rendering or produces 3-D models for analytical, scientific and industrial purposes. There are many varieties of files supporting 3-D graphics, for example, Wavefront .obj files and .x DirectX files. Each file type generally tends to have its own unique data structure. Each file format can be accessed through their respective applications, such as DirectX files, and Quake . Alternatively, files can be accessed through third-party standalone programs, or via manual decompilation. 3-D modeling software

1560-610: The Apple II . 3-D computer graphics production workflow falls into three basic phases: The model describes the process of forming the shape of an object. The two most common sources of 3D models are those that an artist or engineer originates on the computer with some kind of 3D modeling tool , and models scanned into a computer from real-world objects (Polygonal Modeling, Patch Modeling and NURBS Modeling are some popular tools used in 3D modeling). Models can also be produced procedurally or via physical simulation . Basically,

1612-695: The Mars Orbiter Laser Altimeter (MOLA) mapping of Mars, the Lunar Orbital Laser Altimeter (LOLA) and Lunar Altimeter (LALT) mapping of the Moon, and the Mercury Laser Altimeter (MLA) mapping of Mercury. In planetary mapping, each planetary body has a unique reference surface. The quality of a DEM is a measure of how accurate elevation is at each pixel (absolute accuracy) and how accurately

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1664-620: The Terra satellite is also freely available for 99% of the globe, and represents elevation at 30 meter resolution. A similarly high resolution was previously only available for the United States territory under the Shuttle Radar Topography Mission (SRTM) data, while most of the rest of the planet was only covered in a 3 arc-second resolution (around 90 meters along the equator). SRTM does not cover

1716-432: The Terra satellite using double-pass stereo pairs. The HRS instrument on SPOT 5 has acquired over 100 million square kilometers of stereo pairs. A tool of increasing value in planetary science has been use of orbital altimetry used to make digital elevation map of planets. A primary tool for this is laser altimetry but radar altimetry is also used. Planetary digital elevation maps made using laser altimetry include

1768-431: The wire-frame model and 2-D computer raster graphics in the final rendered display. In computer graphics software, 2-D applications may use 3-D techniques to achieve effects such as lighting , and similarly, 3-D may use some 2-D rendering techniques. The objects in 3-D computer graphics are often referred to as 3-D models . Unlike the rendered image, a model's data is contained within a graphical data file. A 3-D model

1820-471: The coordinate system defined. This is where the views can be changed between Layout and Data View. The data will be ordered according to the order in the Table of Contents. The user can create multiple data frames within one table of contents. The data frame while in that view will only view a single data frame at a time. The table of contents is the way that ArcMap represents what data is available to put into

1872-411: The data frame and how each layer is symbolized. The normal way to organize the layers is from top to bottom. With the base map elements such as a street map or DEM listed at the bottom the thematic map layers can be placed above to convey the message the map is being designed for. Other forms to view the table of contents include listing layers by source; visibility; and selection. The most basic form

1924-465: The final form. Some graphic art software includes filters that can be applied to 2D vector graphics or 2D raster graphics on transparent layers. Visual artists may also copy or visualize 3D effects and manually render photo-realistic effects without the use of filters. Some video games use 2.5D graphics, involving restricted projections of three-dimensional environments, such as isometric graphics or virtual cameras with fixed angles , either as

1976-680: The first usable elevation data for a sizeable portion of the planet's landmass, using two-pass stereoscopic correlation. Later, further data were provided by the European Remote-Sensing Satellite (ERS, 1991) using the same method, the Shuttle Radar Topography Mission (SRTM, 2000) using single-pass SAR and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER, 2000) instrumentation on

2028-430: The form of a uniform global coverage with a resolution of 12 meters. ALOS provides since 2016 a global 1-arc second DSM free of charge, and a commercial 5 meter DSM/DTM. Many national mapping agencies produce their own DEMs, often of a higher resolution and quality, but frequently these have to be purchased, and the cost is usually prohibitive to all except public authorities and large corporations. DEMs are often

2080-615: The ice) over Antarctica and Greenland. Another global model is Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) with 7.5 arc second resolution. It is based on SRTM data and combines other data outside SRTM coverage. A novel global DEM of postings lower than 12 m and a height accuracy of less than 2 m is expected from the TanDEM-X satellite mission which started in July 2010. The most common grid (raster) spacing

2132-404: The mesh to their desire. Models can be viewed from a variety of angles, usually simultaneously. Models can be rotated and the view can be zoomed in and out. 3-D modelers can export their models to files , which can then be imported into other applications as long as the metadata are compatible. Many modelers allow importers and exporters to be plugged-in , so they can read and write data in

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2184-539: The mid-level, or Autodesk Combustion , Digital Fusion , Shake at the high-end. Match moving software is commonly used to match live video with computer-generated video, keeping the two in sync as the camera moves. Use of real-time computer graphics engines to create a cinematic production is called machinima . Not all computer graphics that appear 3D are based on a wireframe model . 2D computer graphics with 3D photorealistic effects are often achieved without wire-frame modeling and are sometimes indistinguishable in

2236-402: The native formats of other applications. Most 3-D modelers contain a number of related features, such as ray tracers and other rendering alternatives and texture mapping facilities. Some also contain features that support or allow animation of models. Some may be able to generate full-motion video of a series of rendered scenes (i.e. animation ). Computer aided design software may employ

2288-499: The physical model can match the virtual model. William Fetter was credited with coining the term computer graphics in 1961 to describe his work at Boeing . An early example of interactive 3-D computer graphics was explored in 1963 by the Sketchpad program at Massachusetts Institute of Technology's Lincoln Laboratory . One of the first displays of computer animation was Futureworld (1976), which included an animation of

2340-458: The polar regions and has mountain and desert no data (void) areas. SRTM data, being derived from radar, represents the elevation of the first-reflected surface—quite often tree tops. So, the data are not necessarily representative of the ground surface, but the top of whatever is first encountered by the radar. Submarine elevation (known as bathymetry ) data is generated using ship-mounted depth soundings . When land topography and bathymetry

2392-417: The program to view spatial data. Users can also upload .dbf or database files to link important attribute information to spatial data. Comma separated values (.csv) can be used, as long as they are converted to a .dbf before upload into the program. When a map is saved a new file extension is created (.mxd). This file does not save the layers or spatial data with it, only the relative pathnames. What this means

2444-628: The render engine how to treat light when it hits the surface. Textures are used to give the material color using a color or albedo map, or give the surface features using a bump map or normal map . It can be also used to deform the model itself using a displacement map . Rendering converts a model into an image either by simulating light transport to get photo-realistic images, or by applying an art style as in non-photorealistic rendering . The two basic operations in realistic rendering are transport (how much light gets from one place to another) and scattering (how surfaces interact with light). This step

2496-401: The result is two-dimensional, without visual depth . More often, 3-D graphics are being displayed on 3-D displays , like in virtual reality systems. 3-D graphics stand in contrast to 2-D computer graphics which typically use completely different methods and formats for creation and rendering. 3-D computer graphics rely on many of the same algorithms as 2-D computer vector graphics in

2548-432: The same fundamental 3-D modeling techniques that 3-D modeling software use but their goal differs. They are used in computer-aided engineering , computer-aided manufacturing , Finite element analysis , product lifecycle management , 3D printing and computer-aided architectural design . After producing a video, studios then edit or composite the video using programs such as Adobe Premiere Pro or Final Cut Pro at

2600-405: The temporal description of an object (i.e., how it moves and deforms over time. Popular methods include keyframing , inverse kinematics , and motion-capture ). These techniques are often used in combination. As with animation, physical simulation also specifies motion. Materials and textures are properties that the render engine uses to render the model. One can give the model materials to tell

2652-432: The tree canopy giving readings somewhere between a DSM and a DTM). DTMs are created from high resolution DSM datasets using complex algorithms to filter out buildings and other objects, a process known as "bare-earth extraction". In the following, the term DEM is used as a generic term for DSMs and DTMs. A DEM can be represented as a raster (a grid of squares, also known as a heightmap when representing elevation) or as

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2704-404: Was developed by DHI . Temporal Analyst tool for GIS brings time series data management directly into ArcGIS and provides fully dynamic data handling, modeling and monitoring. 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

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