Full HTML for

Basic foilset 3D Geographical Information Systems in Tango

Given by Remek Trzaska, Pawel Roman, Chris Walczak, Marek Podgorny at CEWES Tango Training on November 17-18 98. Foils prepared November 29 98
Outside Index Summary of Material

Key Features:
High-End Data Visualization
Fly-Through Capability
Database Access
Discrete Event Simulation
Dynamic Layer Switching
Synchronized or Independent Views
Interactive Objects

Table of Contents for full HTML of 3D Geographical Information Systems in Tango

 Denote Foils where Image Critical
Denote Foils where Image has important information
Denote Foils where HTML is sufficient
1 3D Geographic Information System
2 3D Geographic Information System
3 System Overview
4 Collaborative 3D GIS
5 Collaborative 3D GIS
6 Collaborative 3D GIS
7 Collaborative 3D GIS
8 Application Model
9 Advanced Data Processing Techniques
10 Data Transformation Process
11 Satellite Imagery and Maps
12 Digital Elevation Models
13 Wavelets
14 Wavelets (cont'd)
15 Mesh simplification
16 Triangulation
17 Core Technologies
18 Open Inventor
19 Operating in the World
20 Interactive Objects
21 Database Support
22 TIGER/Line Datasets
23 TIGER/Line Data Definition
24 TIGER/Line Data
25 GIS Extensions
26 GIS_Root
27 GIS_Origin
28 GIS_Bounds
29 GIS_Scale
30 GIS_Texture
31 GIS_RectArea and GIS_CircleArea
32 GIS_Object
33 GIS_Slider
34 GIS_Terrain
35 Sample WDF
36 Sample WDF (cont'd)
37 Performance enhancements
38 Overall Communication Architecture
39 Overall Communication Architecture (2)
40 Control Center
41 Communication with the Collaboratory System
42 GIS Protocol
43 Shared State
44 Synchronization
45 Collaborative Architecture
46 Discrete Event Simulation
47 Cooperation with TANGOSim
48 Weather data
49 Wind
50 Isosurfaces (Clouds)
51 Colored Slice
52 Varia

Outside Index Summary of Material

HTML version of Basic Foils prepared November 29 98

Foil 1 3D Geographic Information System

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Remek Trzaska, Pawel Roman, Chris Walczak, Marek Podgorny
NPAC, Syracuse University
HTML version of Basic Foils prepared November 29 98

Foil 2 3D Geographic Information System

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Key Features:
High-End Data Visualization
Fly-Through Capability
Database Access
Discrete Event Simulation
Dynamic Layer Switching
Synchronized or Independent Views
Interactive Objects
HTML version of Basic Foils prepared November 29 98

Foil 3 System Overview

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Goal: visualization of terrain with multiple kinds of data, including satellite images, maps and weather info
  • Open Inventor used as a graphic library and a windowing toolkit
  • "Earth surface" is build with triangles
  • Imaginary data (maps, satellite images, etc.) is projected on the surface
  • DEM & imaginary data is compressed using wavelets
  • Adaptive mesh simplification
  • Delaunay triangulation
HTML version of Basic Foils prepared November 29 98

Foil 4 Collaborative 3D GIS

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Focus: high-end terrain visualization with GIS overlays, integrated with Web
  • Open Inventor Web 3D viewer
    • initially designed as terrain viewer but later generalized to support general 3D visualization
    • as a browser, the viewer exceeds VRML browser functionality
    • supports both synchronous and independent views of data
    • supports multiple windows for different data layers
  • Multi-user functionality provided by TANGO Interactive
  • Support for stereoscopic viewing
HTML version of Basic Foils prepared November 29 98

Foil 5 Collaborative 3D GIS

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Terrain and other GIS data stored on HTTP server and fetched over the network via HTTP protocol
Handles multiple types of GIS data
  • satellite imagery, topographic maps, various geological characteristics (i.e., vegetation, geological resources, and water concentration) and arbitrary 3D objects are visualized (complete database for NYS).
Wavelet compression for both DEM and satellite images, reduces size of data by a factor of 32 for DEMs and 30-60 for textures.
Adaptive mesh simplification technique results in rendering time reduction by a factor of 40.
Internal caching system with pre-processing
Level-of-detail rendering
HTML version of Basic Foils prepared November 29 98

Foil 6 Collaborative 3D GIS

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Extended scene model
  • (Compatible) scene description language
  • Support for dynamic addition of objects to the scene.
  • Support for WWW anchor (link) functionality
  • Objects behavior can be externally controlled - support for simulation and "3D streaming"
  • Support for compound objects, translation vectors
    • enables assembly/disassembly capability
  • Support for linked object/camera duo (object tracking capability)
  • Synchronous and asynchronous master/slave relationship, re-sync mode (all within TANGO Interactive)
HTML version of Basic Foils prepared November 29 98

Foil 7 Collaborative 3D GIS

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Database support: all locations are geo-referenced. Supports "pickable" mode. A "pick" spawns a spatial database query.
Database backend implemented using Informix/Illustra object-relational database
Query refinement via web browser interface
  • programmable selection of canned queries
Database contents:
  • TIGER/Line data, US census data, business data, web domain name database, ..... (complete database for NYS)
Viewer objects can have associated HTML links
HTML version of Basic Foils prepared November 29 98

Foil 8 Application Model

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Master/Slave model:
  • master user chooses the number of windows, their contents, changes the viewer's camera position
  • slave users simply observe reproduced behavior of the master
HTTP
server
Master
Application
Slave
App. #1
Slave
App. #2
CIV
Control Application
Control connection
Binary data connection
HTML version of Basic Foils prepared November 29 98

Foil 9 Advanced Data Processing Techniques

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Wavelet Compression (Embedded Zerotree Algorithm)
Adaptive Mesh Simplification
Triangulation
Discrete Level Of Detail
World Represented as Triangulated Irregular Network (TIN)
HTML version of Basic Foils prepared November 29 98

Foil 10 Data Transformation Process

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Server
Viewer
HTML version of Basic Foils prepared November 29 98

Foil 11 Satellite Imagery and Maps

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Satellite imagery is 29 meters resolution multi-spectral coverage
  • We have processed 12 swaths covering entire New York state
  • The data contains 7 spectral bands, 3 visible, 4 infrared, that can be combined into color images
    • ER Mapper used to create color images for GIS viewer
    • "Special effects" can be obtained by mixing 7 bands in different proportions
Maps: commercial raster maps acquired and processed
HTML version of Basic Foils prepared November 29 98

Foil 12 Digital Elevation Models

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
A DEM consists of a sampled array of elevations for a number of ground positions that are normally at regularly spaced intervals. These intervals determine the spatial resolution of the DEM.
  • The USGS offers DEM in Public Domain having a spatial resolution of 90 m whereas commercial organizations have the DEM's at 30 m.
HTML version of Basic Foils prepared November 29 98

Foil 13 Wavelets

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Wavelet decomposition extracts the most important information (low frequencies) and less meaningful details (higher frequencies)
to compress the wavelet coefficients we use Embedded Zerotree Algorithm:
  • the coefficients describing low frequencies are placed in the front of the stream, higher frequencies are placed further;
  • the coefficients can be roughly approximated using only the beginning of the stream, further part of the stream provides additional refinement information.
HTML version of Basic Foils prepared November 29 98

Foil 14 Wavelets (cont'd)

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Embedded stream lets any application use only a fraction of a stream to obtain some approximation of a image:
Whole stream (14times) 62% of the stream (22t.) 14% (100t.)
Compression ratios used in the system: ~48 times for DEM, ~25 for textures
HTML version of Basic Foils prepared November 29 98

Foil 15 Mesh simplification

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
A full mesh of triangles build on n2 points (nodes) consists of 2(n-1)2 triangles
Most of nodes can be removed without a visual loss of quality
Which of the above terrain models was built with only 10% of nodes??? (Answer: the right one)
HTML version of Basic Foils prepared November 29 98

Foil 16 Triangulation

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
After mesh simplification, the remaining nodes have to be connected into a set of triangles
We use a fast divide-and-conquer 2D Delaunay triangulator.
Every triangle's circumcircle contains only the vertices of this triangle
HTML version of Basic Foils prepared November 29 98

Foil 17 Core Technologies

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Open Inventor
Adaptive Communication Environment (ACE)
TANGO Interactive
TANGOsim
XtIntrinsics and Motif
Standard Template Library
HTML version of Basic Foils prepared November 29 98

Foil 18 Open Inventor

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
OI is a set of C++ classes designed for developing high-performance graphics applications
Its extensibility allows to overcome some of its drawbacks:
  • ability to read & send binary data over the network
  • extensions of the default viewer, for example we can switch between textures using buttons
HTML version of Basic Foils prepared November 29 98

Foil 19 Operating in the World

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Picking
  • Database Access
  • Dragging Objects
  • Picking Objects and Areas
Navigating
  • Six-degree Freedom of Movement
  • Following of the Master or Independent Exploration
HTML version of Basic Foils prepared November 29 98

Foil 20 Interactive Objects

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Hot Spot
  • A geo-referenced area with an associated URL
Pickable Objects
  • A VRML or OI model with an associated URL
URLs are sent to a Web Browser
Draggable Objects
  • A VRML or OI model that can be moved by the user
HTML version of Basic Foils prepared November 29 98

Foil 21 Database Support

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Two-level Access
  • The Nearest Features Window
  • Web Browser Interface
Illustra DBMS by Informix
Spatial Data Blade - Geo-referenced queries
Web Data Blade - HTTP interface
Census Data
Roadfinder based on TIGER/Line
HTML version of Basic Foils prepared November 29 98

Foil 22 TIGER/Line Datasets

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Topographically Integrated Geographic Encoding and Referencing (TIGER) is the system developed by the U.S. Census bureau for mapping purposes
TIGER/Line files are extracts of selected geographic and cartographic information from the TIGER database.
TIGER/Line coverage is available for the entire United States of America.
HTML version of Basic Foils prepared November 29 98

Foil 23 TIGER/Line Data Definition

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Line features
  • Roads, Railroads, Hydrography, Miscellaneous transportation features and selected power and pipe lines, Boundaries
Landmark features
  • schools, churches, public buildings, parks, factories
Polygon features
  • Geographic entity codes for areas used to tabulate the 1990 census statistical data and current geographic areas
HTML version of Basic Foils prepared November 29 98

Foil 24 TIGER/Line Data

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Public domain data loaded into Illustra database along with census data
Illustra supports 2D and 3D spatial queries
2D and 3D viewers support dynamically built overlays constructed on demand from the TIGER/Line and census data
Graphical interface for spatial queries spawned from the 3D viewer
HTML version of Basic Foils prepared November 29 98

Foil 25 GIS Extensions

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
World Description File Format
  • Based on tags (e.g. GIS_Terrain)
  • Compliant to OI format (SoInfo nodes)
Dynamic World Building
  • Dependent on user's selection
World Extensions
  • Automatically added less detailed areas
Movement Constraints
  • No "floating-in-the-void" effect
HTML version of Basic Foils prepared November 29 98

Foil 26 GIS_Root

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
The main part of all the URLs used for downloading terrain data: textures and elevation
Textures will be looked for in /Textures subdirectory, elevation in /DEM subdirectory
DEF GIS_Root Info {
string "http://sandman.npac.syr.edu:8888/GIS"
}
HTML version of Basic Foils prepared November 29 98

Foil 27 GIS_Origin

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
The geographical coordinates (latitude, longitude, and altitude) corresponding to Open Inventor's (0,0,0) point.
Two triplets of integers for latitude and longitude, one integer for altitude.
DEF GIS_Origin Info {
string "76:15:00,43:15:00,0"
}
HTML version of Basic Foils prepared November 29 98

Foil 28 GIS_Bounds

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Coordinates of the 3D box the viewer's camera position is restricted to.
Two pairs of triplets (NW corner, SE corner)
If omitted, camera position is not restricted.
DEF GIS_Bounds Info {
string "76:15:00,43:15:00 75:45:00,42:45:00"
}
HTML version of Basic Foils prepared November 29 98

Foil 29 GIS_Scale

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
scaling factor used to transform geographical coordinates to Open Inventor's coordinate system
a triplet:
  • how many Open Inventor's units correspond to one degree of longitude
  • how many Open Inventor's units correspond to one degree of longitude
  • the divider used to obtain Open Inventor's y-coordinate for a particular altitude
DEF GIS_Scale Info {
string "12000 12000 3"
}
HTML version of Basic Foils prepared November 29 98

Foil 30 GIS_Texture

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Information about one of possibly many texture layers
Two strings, separated by a comma:
  • Partial path, appended to GIS_Root + "/Textures/" pointing to the directory on the HTTP server containing the image data.
  • Description of the texture layer, e.g. "Map," "Vegetation," etc.
DEF GIS_Texture Info {
string "MAP,Map (Scale 1:250 000)"
}
HTML version of Basic Foils prepared November 29 98

Foil 31 GIS_RectArea and GIS_CircleArea

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Definitions of "hot spots"
Those areas have an URL associated with them so that when the user points such a location and clicks the left mouse button, the request to display the URL is sent to the web browser.
For RectArea, coordinates for the rectangle corners, for CircleArea coordinates of the center of the circle and one of the points on the circle's boundary.
DEF GIS_RectArea Info {
string "76:15:00 43:10:00 76:00:00 43:00:00, http://www.sybercuse.com"
}
HTML version of Basic Foils prepared November 29 98

Foil 32 GIS_Object

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
External VRML/Open Inventor model geometry inserted into the GIS virtual world.
A grouping node with two or three children:
  • geographic coordinates of the model's local (0,0,0) point,
  • grouping node describing model's geometry,
  • optional URL to be sent to the web browser when the user clicks on the model's geometry.
DEF GIS_Object Separator {
Info { string "43:15:00 37:00:00 0" }
Group { ... }
Info { string "http://..." }
}
HTML version of Basic Foils prepared November 29 98

Foil 33 GIS_Slider

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
A component of the world that can be translated in one direction (one degree of freedom).
Movements of this object are shared by all the participants.
Three children:
  • vector determining direction of allowed movements
  • translation of the geometry from the (0,0,0) point
  • object's geometry
DEF GIS_Slider Separator {
Info { string "1 1 0" }
Translation { ... }
Separator { ... }
}
HTML version of Basic Foils prepared November 29 98

Foil 34 GIS_Terrain

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Building block of the terrain model.
  • Geographic coordinates of the northwest corner of the terrain chunk
  • Size of the terrain chunk in minutes (currently we use 15- and 30-minute files for most New York State)
  • Mesh simplification threshold. The higher value, the smaller number of triangles is created to produce an approximation of the terrain shape, but the faster rendering. (0.3 for a very precise terrain shape approximation to 1.5 for rough approximations)
  • Preferred texture size in pixels. This can be used to force a wavelet decompressor to produce uncompressed textures smaller than their originals (useful for some OpenGL hardware)
DEF GIS_Terrain Info {
string "76:15:00,43:15:00 15 0.5 512"
}
HTML version of Basic Foils prepared November 29 98

Foil 35 Sample WDF

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
#Inventor V2.0 ascii
Selection {
Environment {
fogType SMOKE
fogVisibility 5000.0
fogColor 0.6 0.6 1.0
}
ShapeHints {
creaseAngle 3.14
}
DEF GIS_Root Info {
string "http://sandman.npac.syr.edu:8888/GIS"
}
DEF GIS_Origin Info {
string "76:15:00,43:15:00 0"
}
DEF GIS_Bounds Info {
string "76:15:00,43:15:00 75:45:00,42:45:00"
}
DEF GIS_Scale Info {
string "12000 12000 3"
}
HTML version of Basic Foils prepared November 29 98

Foil 36 Sample WDF (cont'd)

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
DEF GIS_Texture Info {
string "MAP,Map (Scale 1:250 000)"
}
DEF GIS_Texture Info {
string "SAT,Satellite Image (Resolution 30m)"
}
DEF GIS_Terrain Info {
string "76:15:00,43:15:00 15 0.5 512"
}
DEF GIS_Terrain Info {
string "76:0:00,43:15:00 15 0.5 512"
}
DEF GIS_Terrain Info {
string "76:0:00,43:0:00 15 0.5 512"
}
DEF GIS_Terrain Info {
string "76:15:00,43:0:00 15 0.5 512"
}
DEF GIS_RectArea Info {
string "76:15:00 43:10:00 76:00:00 43:00:00,http://www.sybercuse.com"
}
}
HTML version of Basic Foils prepared November 29 98

Foil 37 Performance enhancements

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Usage of the SoLevelOfDetail class to improve displaying speed
Dynamic downloading of the necessary data while the system is being viewed
Animation of objects according to control information received from the simulation engine
HTML version of Basic Foils prepared November 29 98

Foil 38 Overall Communication Architecture

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
HTML version of Basic Foils prepared November 29 98

Foil 39 Overall Communication Architecture (2)

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Two levels of communication
  • local: between Control Panel and GIS Browsers
  • over the network: between Master Control Panel and Slave Panels via collaboratory system.
HTML version of Basic Foils prepared November 29 98

Foil 40 Control Center

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Viewer Management
Communication with TANGO Interactive
Local Message Dispatching
Graphical User Interface
Overall World Map
HTML version of Basic Foils prepared November 29 98

Foil 41 Communication with the Collaboratory System

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
GIS Control Panel is connected with a collaboratory daemon by means of a socket
Two message channels
  • CONTROL: Control Application and Master Control Panel (CIV protocol)
  • DATA: between Control Panels (GIS protocol)
HTML version of Basic Foils prepared November 29 98

Foil 42 GIS Protocol

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Messages sent from the master to all the
slaves via the control application:
Camera Position Change–the master has made a movement in his GIS window
New URL–the new virtual world has been chosen to be displayed
Windows Contents–the master has turned on/off one of the windows or changed its content (map/weather, walk/fly view)
HTML version of Basic Foils prepared November 29 98

Foil 43 Shared State

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Metadata about Visualized World
Camera Parameters
Hot Spots
Draggable Objects
Pickable Objects
Static and Moving Objects
Initial State Issue
Consistency
Efficiency
HTML version of Basic Foils prepared November 29 98

Foil 44 Synchronization

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Events are translated into compact messages and broadcast to other participants
Communication classes
Dynamic Viewer Protocol
Control Center Protocol
Reliable Transport Protocol - TCP
HTML version of Basic Foils prepared November 29 98

Foil 45 Collaborative Architecture

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Control Center
Other 3D GIS instances or TANGOsim
HTML version of Basic Foils prepared November 29 98

Foil 46 Discrete Event Simulation

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Cooperation with TANGOsim
  • Notion of Virtual Time (4th dimension)
  • Powerful Scripting Language
  • Interoperability with Different Kinds of Applications by use of application Stubs
Static and Moving Objects (VRML or OI models)
Follow-Up Mode
TANGOsim vs DIS
HTML version of Basic Foils prepared November 29 98

Foil 47 Cooperation with TANGOSim

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
TANGOsim
HTML version of Basic Foils prepared November 29 98

Foil 48 Weather data

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Stored in Vis5d format: set of 3D grids of some (weather related) variables
Variables include: temperature, humidity, rainfall, snowfall, wind, etc.
Time introduces 4th dimension
HTML version of Basic Foils prepared November 29 98

Foil 49 Wind

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Vis5d file contains 3 wind components:
  • west to east (variable U),
  • south to north (variable V),
  • down to up (variable W)
Sum of the three gives a direction and speed of wind in a particular point
Dragging handles changes the position of the set of vectors
HTML version of Basic Foils prepared November 29 98

Foil 50 Isosurfaces (Clouds)

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Humidity variable can be used to visualize clouds
Marching Cubes algorithm deployed to create isosurfaces
HTML version of Basic Foils prepared November 29 98

Foil 51 Colored Slice

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
Shows a cut through a 3d grid of any variable
Handles used to change the position of a cut
HTML version of Basic Foils prepared November 29 98

Foil 52 Varia

From 3D Geographical Information Systems in Tango CEWES Tango Training -- November 17-18 98. *
Full HTML Index
All the weather visualization objects are shared with other 3D GIS participants
Open Inventor animation engines deployed to visualize changes of clouds, rainfall, and other variables as time passes.
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