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GEOGRAPHIC INFORMATION SYSTEMS
Lecture 25: 3D Analyst
3D Analyst
- 3D Analyst is an ArcGIS extension designed to work with TIN data (triangulated irregular network)
- many of the tools in 3D Analyst also work with raster data (with some duplicated from Spatial Analyst)
- used to create 3D models of terrain and 3D features (x, y and z values)
- 3D models of terrain
- TINs are usually created from a raster digital elevation model (DEM)
- once a TIN is created, it can be used to create contour maps, slope maps and aspect maps
- 3D features (x, y and z values)
- 3D features (points, lines or polygons) are created from vector data
- assigns a z value to features based upon a height or depth attribute
- 3D features can then be overlaid on the terrain (either a DEM or TIN elevation model)
TIN Data Structure
- the TIN data structure uses irregularly shaped triangular facets to model terrain
- each triangle is defined by three nodes with elevation values (each node has an x,y and z value)
- the three nodes are then connected by lines to form a triangle
- using the x,y and z coordinates of the nodes, each triangular facet has a defined slope and aspect
3D Analyst Tools
- a few of the more important tools contained in the 3D Analyst toolbox include:
- 3D features - used to create 3D features (points, lines or polygons)
- Conversion - used to create a TIN from a raster (e.g. DEM) or raster from a TIN
- Raster Interpolation - used to interpolate a raster surface from sample points or contours
- Raster Surface - used to create contours, slope maps, aspect maps, hillshades, viewsheds
- TIN Surface - used to create contours, slope maps and aspect maps from a TIN
ArcScene
- a separate application program that is included with 3D Analyst
- ArcScene is designed for viewing 3D terrain models and 3D features
- with ArcScene you can pan, zoom, tilt and rotate GIS layers
- the Fly button on the ArcScene toolbar also allows you to fly through the terrain
- to create a 3D terrain model, grid cells in a DEM or nodes in a TIN are assigned a “base height”
- in this case, the base height layer is the same as the original DEM or TIN
- to create a 3D image terrain model, the pixels in an image are assigned a “base height”
- in this case, the base height is either a DEM or TIN with the same extent as the image
- ArcScene can also be used to visualize 3D features overlaid on a terrain model
- to do this, features are assigned a “base height” from either a raster or TIN elevation model
- these features are then extruded based upon a z attribute value
- ArcScene can also be used to create to create and save animations
- you can create and save an animation of a fly-through
- you can also create and save animations to visualize time-series data
- these animations can then be saved as video files (e.g. mpg or avi files)
ArcGlobe
- a separate application program that is included with 3D Analyst
- designed for viewing 2D and 3D features on a virtual globe
- the layers displayed on the globe can be either a raster, vector or TIN layers
- the layers displayed in the ArcGlobe environment maintain their attribute table
- the layers can be symbolized, selected, queried or analyzed on the globe
- note that this is something that cannot be done in Google Earth
Copyright© 2015, Kevin Mulligan, Texas Tech University
GIST 3300 / 5300
Geographic Information Systems
3D Analyst
TIN Data Structure
Triangulated Irregular Network
3D Models of Terrain
3D Features
3D Analyst Application Programs
ArcScene – fly-throughs and animations
ArcGlobe – virtual globe
Geographic Information Systems
3D Analyst Extension
- extension designed to work with TIN data (Triangulated Irregular Network)
- used to create 3D models of terrain (TINs or raster) and 3D features
Geographic Information Systems
3D Analyst Extension to ArcGIS
Some tools found in 3D Analyst are the
same as those in Spatial Analyst
Interpolation tools
Reclass
Surface Analysis
- but there are also many new tools designed to work with TINs
Geographic Information Systems
3D Analyst Extension
1) 3D models of terrain
- TINs are usually created from a raster grid
- TINs can be used to create contour maps, slope maps,
aspect maps, shaded relief (hillshades) and viewsheds
Geographic Information Systems
3D Analyst Extension
2) 3D features (x, y and z values)
- 3D features (points, lines or polygons) are created from vector data
- assigns a z value to features based upon an elevation or attribute value
- 3D features can then be overlaid on terrain
Geographic Information Systems
ArcGIS Extensions
3D Analyst Extension
ArcScene (separate application program included with 3D Analyst)
- designed for viewing 3D terrain models and 3D features
1) used to create 3D fly-throughs of a terrain model
- terrain model can be either a raster or a TIN
2) used to visualize 3D features overlaid on a terrain model
- features are assigned a base height (elevation)
- features are extruded based upon an attribute value
3) can also be used to create animations
- animation of a fly-through
- visualization of time-series data
- these animations are saved as video files (e.g. mpg or avi files)
Geographic Information Systems
ArcGIS Extensions
3D Analyst Extension
ArcGlobe (separate application program included with 3D Analyst)
- designed for displaying 2D and 3D features on a globe
Geographic Information Systems