Vorlesung 5; scale & generalization
Universität Zürich GEO123, Frühlingssemester 2019 Tumasch Reichenbacher
Universität Zürich GEO123, Frühlingssemester 2019 Tumasch Reichenbacher
Bertin's Variablen
Location (xy)
Size
Color (hue, value, saturation)
Shape
Texture
Orientation
Data resoultion / Level of Detail (LoD)
spatial (pixel size, polygon count)
temporal (recording frequency)
attribute
Map scale ranges
small: 1:500'000 oder kleiner, am wenigsten Details, grösste räumliche Ausdehnung (z.B. Landkarte)
medium: weniger räumliche Ausdehnung (z.B. Stadtkarte)
large: 1:10'000 oder grösser, am meisten Details, kleinste räumliche Ausdehnung (z.B. Campuskarte)
Types of scale
areal scale: area size on map vs. in reality
linear scale: linear distance on map vs. in reality
Linear scales
- Representative fraction (RF): numerischer Massstab, z.B. 1:500'000
- Verbal Statements: Beziehung zw. Kartendistanz & Bodendistanz, z.B. "one cm represents one km"
- Graphic Scales: graphic symbol to represent relationship of map units to ground units, z.B. bar scale
Vor-/Nachteile verbal statements (linear scales)
+ intuitiv
- besteht Grössenwechsel nicht (hinein-/hinauszoomen)
Vorteil graphic scales (linear scales)
bestehen bei Grössenwechsel
Generalisierung (kontrollierte Datenreduktion) hat Aspekte von...
...Kunst (subjektiv): was sieht gut aus, Ästhetik
...Wissenschaft (objektiv): Regeln, Gesetze
object generalization (semantic/inhaltlich)
Klassierung und Auswahl der Objekte von Verkehrsnetz, Bebauung, Gewässer, Vegetation
cartographic generalization (geometric)
grafische Generalisierung, lagegenaue & wahrheitsgetreue Darstellung der ausgewählten Objekte unter Wahrung der charakteristischen Form
Generalization process
1. selection
2. classification
3. simplification
(4. symbolisation)
warum generalisieren?
to keep readable at different scales
consequence of scale change
consequence of purpose & audience
wann generalisieren?
- bei Überfüllung
- bei Kollisionen
- bei Konflikten
-bei Komplikationen
Generalisierungsoperationen
- simplification: select critical points, eliminate maximum nr. of coordinates, retain as much of the geometry as possible
- smoothing: shifts object position to improve appearence
- aggregation: merging clusters of points in area
- amalgamation: fusing individual small areas in larger areas
- merging: fusing gropus of lines
- collapse: replacing objects of detailed form by a representative symbol
- refinement: selecting specific portion of an object to represent object
- exageration: making map features larger
- enhancement: controlled & purposeful introduction of detail
- displacement: separating objects
Formalization/ Radical Law
how many features to keep at smaller scales?
Nc = No * Wurzel(So/Sc) (evtl. * cp * cf)
Nc: number of objects at created scale (= to keep)
No: number of original objects
Sc: scale denominator created
So: scale denominator original
cp: map purpose constatn
cf: symbol size
graphic constraints
- graphic density (> 30% black ink)
- just noticable difference (features colliding due to scale change)
- visual perception characteristics (smallest type not below 1.2mm, smallest point not below 0.1mm)
other constraints
- Map purpose:
- map type (reference, navigational, thematic)
- target audience (expert vs. child)
- time available to read (on the road)
- lighting conditions (star gaze map, underwater map)
- Data quality (availability of data? source?)
-Storage space (size of digital file)
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Lernkarten
Bertin's Variablen
Location (xy)
Size
Color (hue, value, saturation)
Shape
Texture
Orientation
Data resoultion / Level of Detail (LoD)
spatial (pixel size, polygon count)
temporal (recording frequency)
attribute
Map scale ranges
small: 1:500'000 oder kleiner, am wenigsten Details, grösste räumliche Ausdehnung (z.B. Landkarte)
medium: weniger räumliche Ausdehnung (z.B. Stadtkarte)
large: 1:10'000 oder grösser, am meisten Details, kleinste räumliche Ausdehnung (z.B. Campuskarte)
Types of scale
areal scale: area size on map vs. in reality
linear scale: linear distance on map vs. in reality
Linear scales
- Representative fraction (RF): numerischer Massstab, z.B. 1:500'000
- Verbal Statements: Beziehung zw. Kartendistanz & Bodendistanz, z.B. "one cm represents one km"
- Graphic Scales: graphic symbol to represent relationship of map units to ground units, z.B. bar scale
Vor-/Nachteile verbal statements (linear scales)
+ intuitiv
- besteht Grössenwechsel nicht (hinein-/hinauszoomen)
Vorteil graphic scales (linear scales)
bestehen bei Grössenwechsel
Generalisierung (kontrollierte Datenreduktion) hat Aspekte von...
...Kunst (subjektiv): was sieht gut aus, Ästhetik
...Wissenschaft (objektiv): Regeln, Gesetze
object generalization (semantic/inhaltlich)
Klassierung und Auswahl der Objekte von Verkehrsnetz, Bebauung, Gewässer, Vegetation
cartographic generalization (geometric)
grafische Generalisierung, lagegenaue & wahrheitsgetreue Darstellung der ausgewählten Objekte unter Wahrung der charakteristischen Form
Generalization process
1. selection
2. classification
3. simplification
(4. symbolisation)
warum generalisieren?
to keep readable at different scales
consequence of scale change
consequence of purpose & audience
wann generalisieren?
- bei Überfüllung
- bei Kollisionen
- bei Konflikten
-bei Komplikationen
Generalisierungsoperationen
- simplification: select critical points, eliminate maximum nr. of coordinates, retain as much of the geometry as possible
- smoothing: shifts object position to improve appearence
- aggregation: merging clusters of points in area
- amalgamation: fusing individual small areas in larger areas
- merging: fusing gropus of lines
- collapse: replacing objects of detailed form by a representative symbol
- refinement: selecting specific portion of an object to represent object
- exageration: making map features larger
- enhancement: controlled & purposeful introduction of detail
- displacement: separating objects
Formalization/ Radical Law
how many features to keep at smaller scales?
Nc = No * Wurzel(So/Sc) (evtl. * cp * cf)
Nc: number of objects at created scale (= to keep)
No: number of original objects
Sc: scale denominator created
So: scale denominator original
cp: map purpose constatn
cf: symbol size
graphic constraints
- graphic density (> 30% black ink)
- just noticable difference (features colliding due to scale change)
- visual perception characteristics (smallest type not below 1.2mm, smallest point not below 0.1mm)
other constraints
- Map purpose:
- map type (reference, navigational, thematic)
- target audience (expert vs. child)
- time available to read (on the road)
- lighting conditions (star gaze map, underwater map)
- Data quality (availability of data? source?)
-Storage space (size of digital file)
