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WO1993004437A1 - Stockage performant de donnees geographiques pour affichages - Google Patents

Stockage performant de donnees geographiques pour affichages Download PDF

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Publication number
WO1993004437A1
WO1993004437A1 PCT/US1992/005175 US9205175W WO9304437A1 WO 1993004437 A1 WO1993004437 A1 WO 1993004437A1 US 9205175 W US9205175 W US 9205175W WO 9304437 A1 WO9304437 A1 WO 9304437A1
Authority
WO
WIPO (PCT)
Prior art keywords
elevational
points
tiles
region
data
Prior art date
Application number
PCT/US1992/005175
Other languages
English (en)
Inventor
Mark H. Johnson
Original Assignee
Hughes Aircraft Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hughes Aircraft Company filed Critical Hughes Aircraft Company
Publication of WO1993004437A1 publication Critical patent/WO1993004437A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
    • G06T17/05—Geographic models
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
    • G09B9/00—Simulators for teaching or training purposes
    • G09B9/02—Simulators for teaching or training purposes for teaching control of vehicles or other craft
    • G09B9/08—Simulators for teaching or training purposes for teaching control of vehicles or other craft for teaching control of aircraft, e.g. Link trainer
    • G09B9/30—Simulation of view from aircraft
    • G09B9/301—Simulation of view from aircraft by computer-processed or -generated image

Definitions

  • This invention relates to a system for processing geographic data, and in particular to a system for efficiently storing and processing elevational geographic data.
  • Geographic information such as image and elevation data is employed in many applications.
  • the combination of elevation and image data can provide relatively realistic simulations of a geographic region.
  • This information may be used, for example, in simulation systems where it is desirable to simulate geographic terrain in three dimensions.
  • simulations are useful as a temporary radar substitute to permit an aircraft to determine the location of nearby geographic features such as hills, while flying at low elevation.
  • image and elevational data is often gathered by using satellite imagery.
  • images of a geographic region are taken by the satellite from different viewing angles.
  • the elevation of particular points can be determined by measuring the apparent shift of features from the different views.
  • this kind of elevational data is available from the Defense Mapping Agency and is called -Digital Terrain Elevational Data" (DTED) .
  • DTED Digital Terrain Elevational Data
  • Such data is typically stored on a grid with elevation values at each coordinate location on the grid.
  • the resolution of the elevation data may be better or worse than the pixel imagery information.
  • the process of producing and displaying three dimensional images can be very time consuming.
  • these images may take the form of a computer generated perspective view of the geographic terrain.
  • the excessive time required to produce an image limits the usefulness of these kinds of three dimensional imaging systems, particularly for real time or near real time applications.
  • One prior approach for dealing with large quantities of elevation data has been to employ a "level of detail" algorithm.
  • the elevation data is reduced by using a regular subset of the information. For example, if elevation data is recorded at 100 foot intervals, the data can be reduced to 1/9 the size by using 300 foot intervals. This approach results in improved data storage for the elevation and image data but the data reduction discards significant information which will cause some hills to be ⁇ ⁇ squashed".
  • an elevational map is produced which includes an elevational value for each defined coordinate location in a coordinate system.
  • a set of curves of the elevational value is created along a single axis of the coordinate system. Points are then identified along each of the curves which have a slope which differ from neighboring points by a value exceeding a predetermined threshold.
  • a new elevational map containing only the identified points is then produced. Tiles in the new elevational map representing elevational features are generated by connecting each of the identified points to adjacent points in adjacent curves which are near the identified points.
  • a three dimensional image of the region is produced from the new elevational map based on the tiles.
  • FIG. 1 is a block diagram of the overall elevational data processing system in accordance with the present invention
  • FIG. 2 is a representati e view of a geographic terrain showing mountains and valleys;
  • FIG. 3 is a view of the storage of elevational data for the terrain in Fig. 2 in accordance with the prior art
  • FIG. 4 is a profile view of the elevational data in Fig. 3 along a single axis
  • FIG. 5. is a view of the curve shown in Fig. 4 with significant points identified in accordance with the techniques of the present invention.
  • FIG. 6 is a representation of the geographic terrain shown in Fig. 2 produced in accordance with the present invention.
  • FIG. 7 is a pair of graphs illustrating a difference technique used in the present invention.
  • FIG. 1 an overall block diagram of a geographic image processing system 10 in accordance with the present invention is shown.
  • the processing system 10 accepts elevational data and imagery data, compresses the elevational data into a representation of elevational features such as hills and valleys and then combines this information with imagery information of the same scene to generate a three dimensional display of a geographic region.
  • elevational data is generated and/or stored in elevational data unit 12.
  • the elevational data consists of geographic data structured on a grid such as the digital terrain elevational data (DTED) available from The Defense Mapping Agency. This data may comprise data representing elevation at individual coordinate points.
  • DTED digital terrain elevational data
  • FIG. 2 there is shown a view of the Los Angeles basis with prominent features such as the San Gabriel Mountains, fans at the base of streams, and smaller hills and features shown.
  • the DTED data for this region consists of a grid of elevational points, such as those shown in FIG. 3. At the DTED level one, the grid points are spaced 300 feet apart; and thus for the 60 mile x 60 mile area shown in FIG. 2, there are 1200 x 1200 points or 1.44 million points. Of course, the DTED data is available at other levels so that grid points may alternatively be spaced at 3 feet, 30 feet, and 3000 feet for example.
  • the elevational data is received and stored in the elevational data generation and storage block 12 in FIG. 1. Also, imagery data for the same region is received and stored in the image data unit 14 in FIG. 1. This data may consist of conventional pixel information which may have greater, less, or the same resolution as the elevational data.
  • the elevational data processor 16 produces a compressed representation of the elevational data, containing which tiles which represent elevational features.
  • This tile information is then transferred to an image generator unit 20 which also receives the imagery information from the image data unit 14.
  • the image generator 20 then combines the imagery information with the compressed elevation information to produce a simulated three dimensional representation of the geographic region shown in FIG. 2.
  • Image generator 20 may generate for example, a three dimensional perspective view from a desired perspective viewpoint.
  • Image generator 20 may consist of a computer image generation system such as "Photovision 4», manufactured by Hughes Training Incorporated of Arlington, Texas.
  • a display unit 22 receives the three dimensional display information and displays the information to the viewer or other control system depending on the particular application.
  • this volume of data is reduced by identifying features representing hills and valleys in the elevational data as follows.
  • FIG. 4 there is shown a profile view of the elevational data shown in FIG. 3 along a single axis.
  • FIG. 4 contains a curve 24 which is a " plot of elevation along the vertical axis verses geographic position in the geographic region in FIG. 2. That is, curve 24 represents the elevational data for a single vertical line along the DETD grid of elevational data shown in FIG. 3. Curve 24 indicates a peak on the left side where the San Gabriel mountains exist.
  • curve 24 is shown with particular points 26 identified. These points represent elevational data points on the curve 24 where the curve undergoes a relatively sharp transition. It will be appreciated that various mathematical techniques may be employed to identify points 26. In accordance with the preferred embodiment, the slope for each point may be calculated and then points identified where the difference in slope between successive points exceeds a predetermined threshold. This may be done by using conventional difference techniques. For example, referring to FIG. 7, at three points on a line (X 0 , Y 0 , Z 0 ) , (X 0 , Y 0 + dy, Z.), ( ⁇ 0 » Y o + 2dy. Z o ), the slope along the Y-axis is 1.
  • Points 26 are then identified in this manner for each vertical data column on the grid shown in FIG. 3.
  • identified points 26 are connected to points in adjacent curves 24 that are in close proximity. For example, this may be done by connecting each identified point 26 with identified points in neighboring curves 24 that lie within a second predetermined threshold distance away from the first point 26.
  • the identified elevational points 26 and their connecting lines may be plotted as shown in FIG. 6.
  • the result is a series of lines 28 and tile ' s 30 which represent elevational features such as hills and valleys in the geographic terrain.
  • FIG. 6 By comparing FIG. 6 with FIG. 2, it can be seen that the tiles 30 and lines 28 roughly correspond with the hills and valleys of the geographic region shown in FIG. 2. It is important to note that FIG. 6 retains only the elevational data of these significant points 26. All other points on the curve 24 having been eliminated. This data reduction performed by the elevational data processor 16 in FIG. 1 greatly reduces the amount of data which must be handled by the image generator unit 20 in FIG. 1. It should be noted that the tiles 30 may connect adjacent identified points 26 which vary in elevation. That is, the line forming tiles may represent a sloping feature of varying elevation as well as a peak or valley of a constant elevation. This is because the connection of adjacent identified points 26 is made on the basis of their distance from each other on the coordinate grid of FIG. 3 and not on the basis of the difference in actual elevational data stored for those points.
  • the improvements in processing speed for the reduced data may be estimated as follows. In one typical system where there are 100 pixels per tile and 36,000 tiles, it takes about 2.5 seconds to process a total image. This is calculated as follows: 2 microseconds per row setup (Step 1)
  • Step 1 0.5 microseconds per pixel
  • Step 2 0.5 microseconds per pixel
  • Total/tile 70 ⁇ sec.
  • the present invention provides an elevational data processing system which greatly reduces the quantity of elevational data to thereby speed up the production of three dimensional geographic images.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Software Systems (AREA)
  • Remote Sensing (AREA)
  • Computer Graphics (AREA)
  • Computer Hardware Design (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Business, Economics & Management (AREA)
  • Educational Administration (AREA)
  • Educational Technology (AREA)
  • Processing Or Creating Images (AREA)
  • Instructional Devices (AREA)

Abstract

Un système de traitement d'images géographiques (10) comprend une unité de données d'élévation (12), une unité de données d'imagerie (14), un processeur de données d'élévation (16), un processeur de génération d'images (20) et une unité d'affichage (22). Le processeur de données d'élévation (16) réduit largement le nombre de points de données d'élévation en identifiant les collines et les vallées dans les données d'élévation. Les collines et les vallées sont identifiées par des points d'identification (26) présentant des différences importantes en inclinaison le long d'une courbe de hauteur (24) dans lesdites données d'élévation, et ensuite en créant des carreaux (30) et des lignes (28). En mémorisant et en traitant uniquement des informations concernant les carreaux (30) et les lignes (28), la quantité de données d'élévation exigée pour produire une image tridimensionnelle est largement réduite. Ceci a pour conséquence une capacité de traitement beaucoup plus rapide pour le système de génération d'images (20).
PCT/US1992/005175 1991-08-15 1992-06-22 Stockage performant de donnees geographiques pour affichages WO1993004437A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US74563391A 1991-08-15 1991-08-15
US745,633 1991-08-15

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WO1993004437A1 true WO1993004437A1 (fr) 1993-03-04

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996013812A1 (fr) * 1994-10-29 1996-05-09 Masaharu Ishii Dispositif et procede de reproduction de modele de terrain
EP0863487A1 (fr) * 1997-03-06 1998-09-09 Aerospatiale Societe Nationale Industrielle Procédé et dispositif pour déterminer le contour de vallées d'une zone géographique déterminée et applications
US6697497B1 (en) 1998-12-22 2004-02-24 Novell, Inc. Boundary identification and characterization through density differencing
WO2004109604A1 (fr) * 2003-06-06 2004-12-16 Atlas Elektronik Gmbh Procede de production d'un modele topographique tridimensionnel
WO2007037986A3 (fr) * 2005-09-21 2007-11-01 Boeing Co Creation de bases de donnees de terrain optimisees
US8326048B2 (en) 2007-10-04 2012-12-04 Microsoft Corporation Geo-relevance for images
CN117745962A (zh) * 2023-12-12 2024-03-22 北京超维创想信息技术有限公司 一种地质模型三维可视化方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0292903A2 (fr) * 1987-05-28 1988-11-30 Honeywell Inc. Générateur numérique de lignes de contour
BE1002267A7 (fr) * 1989-05-22 1990-11-13 G T Geol Tools Ltd Procede de traitement et de presentation de donnees geologiques sous la forme de cartes statistiques et interpretatives.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0292903A2 (fr) * 1987-05-28 1988-11-30 Honeywell Inc. Générateur numérique de lignes de contour
BE1002267A7 (fr) * 1989-05-22 1990-11-13 G T Geol Tools Ltd Procede de traitement et de presentation de donnees geologiques sous la forme de cartes statistiques et interpretatives.

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996013812A1 (fr) * 1994-10-29 1996-05-09 Masaharu Ishii Dispositif et procede de reproduction de modele de terrain
US6272448B1 (en) 1994-10-29 2001-08-07 Kobashigawa Apparatus and method for terrain model reproduction
EP0863487A1 (fr) * 1997-03-06 1998-09-09 Aerospatiale Societe Nationale Industrielle Procédé et dispositif pour déterminer le contour de vallées d'une zone géographique déterminée et applications
FR2760555A1 (fr) * 1997-03-06 1998-09-11 Aerospatiale Procede et dispositif pour determiner le contour de vallees d'une zone geographique determinee et applications
US6104408A (en) * 1997-03-06 2000-08-15 Societe Nationale Industrielle Et Aerospatiale Process and device for determining the contour of valleys of a specified geographical area and applications
US6697497B1 (en) 1998-12-22 2004-02-24 Novell, Inc. Boundary identification and characterization through density differencing
WO2004109604A1 (fr) * 2003-06-06 2004-12-16 Atlas Elektronik Gmbh Procede de production d'un modele topographique tridimensionnel
WO2007037986A3 (fr) * 2005-09-21 2007-11-01 Boeing Co Creation de bases de donnees de terrain optimisees
US8326048B2 (en) 2007-10-04 2012-12-04 Microsoft Corporation Geo-relevance for images
US8774520B2 (en) 2007-10-04 2014-07-08 Microsoft Corporation Geo-relevance for images
CN117745962A (zh) * 2023-12-12 2024-03-22 北京超维创想信息技术有限公司 一种地质模型三维可视化方法

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