Geographic Information
Systems
planning:
Essentials of Geographic Information System; Campbell & Shin:
CH1, CH2, CH3, CH4, CH5.2, CH5.3, CH5.4, CH6.2, CH7, CH8
Mapping, Society, and Technology; Manson
CH1, 3, 4, CH5, CH9
see Brightspace:
Computational Thinking for Problem Solving
Jensen: CH7
Privacy in Research, FutureLearn
mock exam:
question 3: Select By Location → schools
erase → fastfood buffers
question 4: Clip raster
Lecture 1: Introduction to GIS and spatial data
First Law Geography
“Everything is related to everything else, but near things are more related than
distant things” (Tobler, 1970)
Geographic Information Systems 1
, When is GIS useful; Answering questions about geographic …
• Location - The position of a phenomenon on the surface of the earth.
• Distribution - Describes how phenomena are spread across the surface of the
earth.
• Interaction - Describes the linkages and relationships between places.
• Change - Refers to the persistence, transformation, or disappearance of
phenomena on the earth.
→ even though bigger hospital
people are more prone to travel
longer for, now people on the north
have to travel really far even for
smaller
› Geometry: position, size, orientation
› Theme (attribute)
› Topology: Underlying relationship
› Metadata: when it is taken
› Representation
Geographic Information Systems 2
, Saved as either Vector or Raster
data model
Vector Data Model: A data structure
that uses points, lines, and polygons
to represent spatial features:
Point objects Line objects
› X-, Y-cordinate (metric) Node
› Longitude, Latitude › Beginning and end points line
› connection point between lines
Vertex – Vertices
› ‘curving points’ between nodes
Attribute - geometry
› Length
Polygon objects
Node
› Start node = end node
› Shared boundaries created by
shared nodes (and vertices)
Attributes - geometry
Geographic Information Systems 3
, › Outline
› Surface
Choice of geometry type dependents on scale
Each type of geometry is stored in a separate layer! (one for points, lines and
polygones)
Raster Data Structure: A data
structure that uses a grid consisting
of rows, columns, and cells to
represent spatial data.
› Raster is both the geometry and
the attribute table
› One value in each per cell
› All cells contain values
Resolution = cell size
LGN: Land cover Netherlands
Discrete / ‘categorical’ / Continuous / ‘non-discrete’ /
discontinuous data: ‘surface’ data:
› represents objects › represents ‘phenomena’
› boundaries are known › boundaries are vague (zoom in →
› boundaries are ‘sharp’ blocks)
› values derived from measurements
Conversion? → Not always a good idea!
• Loss of detail
• Loss of accuracy
• Stair stepping (raster to vector)
• Changes to the original data
Geographic Information Systems 4
Systems
planning:
Essentials of Geographic Information System; Campbell & Shin:
CH1, CH2, CH3, CH4, CH5.2, CH5.3, CH5.4, CH6.2, CH7, CH8
Mapping, Society, and Technology; Manson
CH1, 3, 4, CH5, CH9
see Brightspace:
Computational Thinking for Problem Solving
Jensen: CH7
Privacy in Research, FutureLearn
mock exam:
question 3: Select By Location → schools
erase → fastfood buffers
question 4: Clip raster
Lecture 1: Introduction to GIS and spatial data
First Law Geography
“Everything is related to everything else, but near things are more related than
distant things” (Tobler, 1970)
Geographic Information Systems 1
, When is GIS useful; Answering questions about geographic …
• Location - The position of a phenomenon on the surface of the earth.
• Distribution - Describes how phenomena are spread across the surface of the
earth.
• Interaction - Describes the linkages and relationships between places.
• Change - Refers to the persistence, transformation, or disappearance of
phenomena on the earth.
→ even though bigger hospital
people are more prone to travel
longer for, now people on the north
have to travel really far even for
smaller
› Geometry: position, size, orientation
› Theme (attribute)
› Topology: Underlying relationship
› Metadata: when it is taken
› Representation
Geographic Information Systems 2
, Saved as either Vector or Raster
data model
Vector Data Model: A data structure
that uses points, lines, and polygons
to represent spatial features:
Point objects Line objects
› X-, Y-cordinate (metric) Node
› Longitude, Latitude › Beginning and end points line
› connection point between lines
Vertex – Vertices
› ‘curving points’ between nodes
Attribute - geometry
› Length
Polygon objects
Node
› Start node = end node
› Shared boundaries created by
shared nodes (and vertices)
Attributes - geometry
Geographic Information Systems 3
, › Outline
› Surface
Choice of geometry type dependents on scale
Each type of geometry is stored in a separate layer! (one for points, lines and
polygones)
Raster Data Structure: A data
structure that uses a grid consisting
of rows, columns, and cells to
represent spatial data.
› Raster is both the geometry and
the attribute table
› One value in each per cell
› All cells contain values
Resolution = cell size
LGN: Land cover Netherlands
Discrete / ‘categorical’ / Continuous / ‘non-discrete’ /
discontinuous data: ‘surface’ data:
› represents objects › represents ‘phenomena’
› boundaries are known › boundaries are vague (zoom in →
› boundaries are ‘sharp’ blocks)
› values derived from measurements
Conversion? → Not always a good idea!
• Loss of detail
• Loss of accuracy
• Stair stepping (raster to vector)
• Changes to the original data
Geographic Information Systems 4
