Lecture 3: Terrain Representation

Las Vegas Flight Tracks

Caption

LA The Movie

Today’s Lecture

Terrain Representation

Announcements

This week’s Lab

In the Map Library

I’ll be there as your Trip Planning Consultant

Attendance at this week’s lab is optional

come if you want, and

use me as a resource if you wish

Questions?

Readings for Next Week are...?

The Readings for Today’s Lecture were?

What does Chapter 3 Map Abstraction Process talk about?

What are some of the main topics under which the chapter’s contents are organized?

Make sure to cover this Chapter as a “self-study unit”

We won’t cover it in the lecture

It is an important part of your readings

Terrain Representation

The organization of the chapter in the text book

Relative Relief Methods

Relief Globes

and their vertical exaggeration

Relief Models

Example of Babcock College in Wellesley MA

Raised relief topographic maps (Hubbard ILL.)

Image Maps

Standard Photos

Single photos

terrain reversal in vertical and low oblique air photos

Stereo Photos

Fig 5.5

stereoscopes - Fig. 5.6

stereograms - Fig 5.7

Radar and Sonar Images

Landscape (Landform) Drawings

Block Diagrams - Fig5.10

Vantage Point -

vertical: plan view

oblique: perspective views

horizontal: profiles

Smooth Shading

Shaded Relief techniques - also called smooth or plastic shading

illumination effects - Fig 5.13

Perspective Profiles

line based representation of surfaces

also known as fishnet maps, wireframe diagrams

Hachures - Fig. 5.15

Stylized Drawings

Combined Relative Relief Methods

Break

Absolute Relief Methods

Quantative measure - not just qualitative visual

tidal surface of reference

MSL Datum - Fig 5.17

Physical Models can be used

but these raised relief models are impractical

Digital Terrain Data

Spot Heights (Spot Elevations) - Fig. 5.18

Digital Elevation Models (DEM) - Fig. 5.19

Contour Lines - Fig. 5.20

Making a profile reveals the logic behind the contour representation: Fig. 5. 22

How biased: Fig. 5.23

Why do contour lines bend upstream? Fig. 5.24

Special Contours - Fig. 5.25

Stereo Models

contour map stereopairs

Anaglyphs

A virtual stereo airphoto mission (on the Moon) [Anaglyph]

Enhanced Contour Lines

e.g. hypsometric layer tint (Fig. 5.27)

Combined Absolute Relief Methods

Composite Relief Methods:

Superimposed Representations - Fig 5.29

Another type of Superimposed Representations -

“Drape image over terrain”

Example “Moon this is Cessna, OVER”

Dual Representations

Fig. 5.31

Active Representations

Interacting with or Querying a GIS

Dynamic Relief Methods

Animated Methods (Example: LA The Movie)

Interactive Methods

Example: Catalina Island Enhanced Relief

Conclusions

‘til next week!