Introduction

Question 1

What is the difference between data, information and service?

Answer 1

Data: representations that can be operated upon by a computer. Specifically, by spatial data, contains positional values, such as (x,y) coordinates.

Information: Data that has been interpreted by a human being. Humans work with an act upon information, not data. Human perception and mental processing lead to data.

Service: Conditions at one place are not the same as conditions elsewhere

Question 2

Why is geospatial information special?

Answer 2

Geographical Information System is the art, science, engineering and technology associated with answering geographical questions. Geo-information answers what, where, why, when, how and how much.

Question 3

What are specialties of geo-information?

Answer 3

Spatial and temporal dependence - All things are related.

Spatial heterogeneity - Conditions in different places are different.

User interest is place-sensitive – Information of a place is of greater importance to users living in that place than it is to users elsewhere.

Question 4

Use examples to explain these terms: Entities, phenomena and fields.

Answer 4

Entities: A set of spatially discrete objects that litter an empty space (e.g. cities, roads, rivers)

Phenomena: Things that dynamically happen (e.g. brush fires, floods, droughts, erosion, urban growth)

Fields: Spatially continuous functions with a unique value everywhere in space (e.g. topographic elevations, air temperatures, soil moisture content)

Question 5

Explain the typical workflow of GIS.

Answer 5

Spatial data modelling: Acquisition  Integration  Update)

Spatial data handling: Visualization  Analysis

Question 6

Explain the difference between Euclidean distance and Manhattan (taxicab, L2) distance.

Answer 6

 Euclidean space (i.e. Euclidean distance) is a straight-line distance

 Gridded space (i.e. Manhattan, taxicab, L1 distance) is the sum of the x and y components.

Question 7

How do you understand the multiple dimensions of geo-information?

Answer 7

 Space: Continent, coordinates, address, direction, distance, which part of region

 Time: Time, date, passage of time, speed of change, what happened around the same time, which came first

 Theme: Topics related to the space being examined

 Scale/resolution: Level of detail, abstraction degree

 Quality: Difference between data model and reality; depends on context

Question 8

What do you understand under the term “ontology”?

Answer 8

Ontology is the process by which things are defined and given meaning.

Philosophical view
 There are things in space and time that have known and unknown properties.
 Things are spatial-temporal clusters with known properties

Cognitive and social-cultural views
 Different realities exist for different minds and different domains.

Question 9

What are the main research challenges of geo-data?

Answer 9

 Handling of time: The “time slice” model consists of an ordered sequence of time-stamped maps. Events and their cause may be missed if they happen between intervals.

 Handling of non-metric space: Geo-coded locations use pre-existing measures of proximity (e.g. distance). Proximity based on time (e.g. travel time between two locations) cannot be represented by proximity based on distance (e.g. a road).

 Handling of inexact space and time: Geometric properties of entities and phenomena may not be clear (fuzziness). The state of our knowledge may not be accurate (uncertainty).

 Handling of multiple views of space and time: Users have different perceptions. Translating multiple and sometimes conflicting perceptions into a data model is difficult.