Foundations of Geographic Information Systems Final Project
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Lecture8.pptGIS 5103 – Fundamentals of GIS
Lecture 8
3D GIS
- Dimensionality
- A dimension is the minimum amount of coordinates needed to define the mathematical space of an object.
Lecture 8 – 3D GIS
- 2D
- A figure that has only length & height as its dimensions.
- 2D shapes lie on a flat surface; known as plane figures or plane shapes.
- While they have areas, 2D shapes have no volume.
- 2D figures are plotted on two axes, the x- and y-axes.
Lecture 8 – 3D GIS
- 3D
- Length + Height + Width
- X + Y + Z
- Volume + Surface Area
- Examples include:
- 3D multi-patch building, roof, interior floors, and foundation would all contain different z-values for the same 2D coordinate.
- Aircraft's 3D position or a walking trail up a mountain, would only have a single z-value for each X,Y location.
Lecture 8 – 3D GIS
- 2.5D
- Highly used in GIS to represent Z data that is not continuous = 3D
- Z data does not need to be elevation.
- Pollution, # of cases, etc.
Lecture 8 – 3D GIS
- 3D file types
- .3dd
- .sxd
- When you import an ArcGlobe or ArcScene document:
- First the .3dd file opens by default in global mode
- Secondly the .sxd file opens in local mode.
- Any new blank scene view defaults to global mode.
Lecture 8 – 3D GIS
- Data Types
- Vector Features
- Point / Line / Polygon
- Surface types
- TIN (Triangular Irregular Networks)
- DEM’s (Digital Elevation Models)
- Raster Surface
- LAS Dataset
Lecture 8 – 3D GIS
- 3D Styles
- Points
- Geometric Shapes
- Models
- Markers
- Imported
- Lines
- Textured Symbols
- Geometric Shapes
- Polygons
- Texture Fill
- Basic Colors
Lecture 8 – 3D GIS
Lecture 8 – 3D GIS
- Perspective View
- Perspective drawing is the most common drawing mode in 3D, where features in the foreground are shown larger than those off in the distance. This matches the way we see the world in our day-to-day lives, and the result is a realistic representation of 3D content.
- All scenes open in perspective viewing mode. You can switch between Perspective Perspective View and Parallel Isometric View viewing modes using the Drawing Mode drop-down menu in the Scene group on the View tab.
Lecture 8 – 3D GIS
- Parallel / Isometric View
- Parallel drawing renders the 3D view using a parallel projection, where features of the same physical size are rendered on-screen identically, regardless of their distance from the viewing camera. Parallel drawing is useful for architectural drawings, as well as for representing statistical data in a 3D view, such as extruded shapes symbolizing numeric values.
Lecture 8 – 3D GIS
- 3D Analyst Tools
- Data Conversion/Preparation
- Txt / Binary / Feature class / Raster / TIN
- Surface Creation
- Interpolation / LASD Creation
- Surface Analysis
- Aspect / Slope / Contour / Feature Interpolation
- 3D Operator & Visibility
- Skyline / Inter-visibility / Sun Shadow Analysis
Lecture 8 – 3D GIS
There are five exploratory analysis tools:
- The Line of Sight tool creates sight lines to determine if one or more targets are visible from a given observer location.
- The View Dome tool determines the parts of a sphere that are visible from an observer located at the center.
- The Viewshed tool determines the visible surface area from a given observer location through a defined viewing angle.
- The Slice tool visually cuts through the view's display to reveal hidden content.
- The Cut and Fill tool provides volume calculations while visually demonstrating the surface area where the ground will be filled or removed.
Lecture 8 – 3D GIS
Exploratory Analysis Tools
- The first three analysis tools determine the visible sight lines, field of view, or spherical visibility coverage.
- The Slice tool temporarily removes displayed content using clipping planes as volumes.
- The Cut and Fill tool calculates volumetric displacement using a planar surface.
- In all cases, the results are temporary and must be saved as feature classes if you want to reload the interactive objects again.
Lecture 8 – 3D GIS
- illumination properties
- A unique element to authoring scenes is that you can also define illumination properties. This includes properties such as the time of day, whether or not the sun casts a shadow, and how much ambient light is used. In global mode, you can also simulate atmospheric diffusion.
Lecture 8 – 3D GIS
By the end of this week you should be able to:
- Understand dimensionality
- List the differences between 2D vs 2.5D vs 3D
- Know the data types, Views, & Scene Types for 3D GIS
- Understand Surfaces & How to create/find them
- Familiarize yourself with the Exploratory & Analyst tools
- List the unique properties of 3D GIS vs Traditional 2D maps
- Comprehend the issues of 3D GIS
Lecture 8 – 3D GIS
