Systems for data processing, anaylsis and representation

Allam, Mosaad; Plunkett, Gordon

Bibliographic data

Monograph

Persistent identifier:: 1067490280

Title:: Systems for data processing, anaylsis and representation

Sub title:: ISPRS Commission II Symposium : June 6 - 10, Ottawa, Canada

Scope:: 1 Online-Ressource (XX, 530 Seiten)

Year of publication:: 1994

Place of publication:: Ottawa

Publisher of the original:: The Surveys, Mapping and Remote Sensing, Natural Resources Canada

Identifier (digital):: 1067490280

Illustration:: Illustrationen

Signature of the source:: ZS 312(30,2)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Allam, Mosaad; Plunkett, Gordon

Corporations:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Adapter:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Founder of work:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Other corporate:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: [Tuesday, June 7, 1994]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: [Session D-2 WG II/2 - Hardware and Software Aspects of GIS - Part A]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: [3D] VIRTUAL GIS, A NEW REALITY By Nickolas L, Faust [...] Dharmajyoti Bhaumik [...] Ryan Woodard [...] Dung Vu [...]

Document type:: Monograph

Structure type:: Chapter

III. HIGH QUALITY/HIGH SPEED RENDERING GTRI initially developed perspective scene rendering in the mid 1970's. Since that time development has occurred both in computing and graphics hardware , but also in the software implementation of perspective view algorithms. Whereas, most of the perspective generation techniques were implemented in somewhat system specific Fortran code in the 70's and early 80's, today's trend is toward C and C+ + versions of rendering algorithms that can be directly implemented on almost any Unix workstation. There are many aspects of rendering that must be considered when designing or implementing a system. One must determine the necessary quality of a perspective image that is required by an application. Next, one must determine how fast that rendering process needs to happen to adequately support the application. Usually, the higher the quality of the rendered scene, the longer the time is for rendering. For a number of years, Georgia Tech has made the distinction that it would rather produce higher quality rendering than faster rendering of lower quality images. With today’s technology, that distinction may not have to be made. Flight simulation companies, until recently, have always relied on high speed specially designed hardware to achieve real time rates. When a scene was to be rendered, a multi- processing or parallel environment was used to render terrain and natural and manmade objects. Before the use of high speed random access memory (RAM) and video RAM, a display list of polygons and vectors was used to sort which things within the terrain and objects should be placed in front of others. Since this sorting and the display of the result had to be accomplished in 1/30th of a second, only limited resolution databases and object descriptions were allowed. In all except the very high end simulators (6 to 10 million dollars), the real time simulation looked cartoonish and was 116 not totally effective in training. A person training on the system often would get distracted by graphical artifacts instead of concentrating on the content of the image presented. The larger simulation systems used a large number of specialized processors, and the computing engines, themselves, sometimes occupied whole rooms. The advent of cheaper RAM and video RAM caused most manufacturers to switch to a more effective rendering technique using a depth buffer approach instead of sorting polygons and vectors by distance and then displaying the results. The depth buffer replaced the sorting function of the rendering. The depth buffer was memory associated with every image picture element (pixel) that held the distance between the viewer and that point on the terrain. Individual terrain polygons could be then rendered in a brute force manner using the depth buffer to automatically provide the sorting. As each polygon from the terrain or object was considered, the world coordinates of each vertex of the polygon was geometrically transformed into the output image space and an interpolation process was used to fill in the color values within the output image based on the distance in the depth buffer for that image pixel. By the late 1980's, the depth buffer approach was being used even in the most expensive simulation systems. To achieve the necessary update rates, parallel processing and multi-processing hardware were still used with the depth buffer common to all rendering processes. Texture mapping was used in many of the simulation systems to provide artificial detail in areas of the terrain that were of little interest. ^ Generic, mathematical textures were developed for tree canopy, grass, brick buildings, etc. where a regular function could add detail to a terrain polygon. Much expertise was required in a simulation design to determine which parts of a database needed could ; Techni were polygo given comple polygo while adequa polygo this te represe compu high re manma Norma given second terrain the obj may n tradeof always In the trend generic determ image used. project mather determ Instead transfo transfo popula especie portray urban | environ to desc to see rectang digitize be maj simulat photo 1 polygo

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