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Cartography and Geomatics
• Cartography: The art, science and technology
of making maps
• Map: A two dimensional scaled representation
of a planetary surface
(‘traditional’ definition)
- includes online displays, animations
• Geomatics:
An umbrella term for the
mapping technologies (managing spatial data)
Map Basics
• The nature of mapping
• Uses and purpose of maps and spatial data
• Types of maps and data
• Map and data layers
• Mapping Scales
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1a. Mapping is never finished (for us)
1b. There are multiple map products for the same area
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General uses / purpose of Maps & Spatial data
A. Display and store of spatial information (space)
B. Historical record of spatial features
(time)
General use/purpose of Maps & Spatial data
A.
Display and store of spatial information
B. Historical record of spatial features
Kakwa Park, BC 1920
2010 (google maps)
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Map purpose: C. Communication tool
Map purpose: C. Communication tool
Library books borrowed by country - cartogram
Example: http://www.worldmapper.org/
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General Uses of Maps & Spatial data
C: Communication tool e.g. propaganda
German map, world war II
General Use/purpose of Maps & Spatial data
D. ‘Vicarious’ travel
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D. Vicarious travel (or a work of art)
E. Maps as a work of art
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Maps as a work of art ?
Types of Maps and data
There are traditionally two main types of map and data categories:
a. General purpose (topographic)
These show the visible features of the landscape
e.g. relief, water bodies, and roads - base maps, relief maps, city maps.
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Types of Maps and data
b. Special purpose (thematic)
Emphasis is placed on a particular element
e.g. climate, geology, population density, industry.
Global coffee consumption
http://www.theguardian.com/news/datablog/interactive/2011/dec/01/world-corruption-index-transparency-international-map
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Summary Map purpose (use)
This is the preliminary question in map design/production
1. Function – spatial display, historical, communication, artistic
2. General – topographic or thematic or mixture
3. Specific – what is this map for ?
Map and data layers
Maps and databases are composed of layers or themes –
‘feature’ types are organised in layers e.g. containing roads, rivers etc..
There are three types (vectors): points, lines and areas (polygons)
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Raster (grid) layers
In addition to the 3 ‘feature’ types, there are continuous
grids (rasters) e.g. for air photos, images, relief models
Spatial data: location and attributes
Map layers encode two different types of information:
a. Spatial location (where is it ?)
b. Attributes (what is it ?)
………………………………………………………………………………………..
In GIS software, these data are stored in a single layer
(but with multiple files)
e.g. Roads as a ‘shapefile’
roads.shp
roads.dbf
roads.shx
This differs from mapping / non-GIS software
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Map Scales
Scale represents the reduction compared to the
distances on the earth's surface.
Without a scale, it is a ‘diagram’, (not a map)
Scale can be given in 3 ways:
a. Verbal statement
•
For example, 1 cm to 10 km, 1 inch to 1 mile
•
Verbal statements are simple to understand
•
They are ‘unit-dependent’
b. Scale bar
•Graphic, units are stated
e.g. kilometres or miles
•The left end of the bar can be subdivided in smaller units for
easier estimation of precise distances.
•This practice is only appropriate for topographic maps.
•This is widely abused with GIS software
Topographic
Thematic
‘Classic’ traditional scale bars
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c. Ratio or
‘representative fraction (RF)’
•This states the reduction as a fraction or ratio
(e.g. 1:100,000 or 1/100,000 )
•It is free of specific units (metric or imperial)
•It can describe map series and datasets (e.g. 1:50,000)
•1:20,000 is a larger scale than 1:50,000
(1/20,000 IS bigger than 1/50,000)
Conversion between a statement
and a representative fraction
Get each side of the scale into same units, for example:
To convert 1 cm to 1 km into a ratio:
1 km = 1000m = 100,000 cm
So 1cm to 1km is the same as 1:100,000
To convert 1:250,000 to a statement:
1 cm to 250,000 cm = 2500m = 2.5 km
Scale is
1 cm to 2.5 km
More: http://www.nrcan.gc.ca/earth-sciences/geography/topographic-information/maps/9795
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common world scales / metric map series
1:1,000,000 (world)
Small
1:500,000
-------------------------------1:250,000
Medium
(1:125,000)
-------------------------------1:50,000
Large
1:20,000 (provincial)
-------------------------------1:10,000
(cadastral)
Very large
common world scales / imperial series
Canada converted to metric post world war II
1:506,880
1” = 8 miles -> 1:500,000
-------------------------1: 253,440
1” = 4 miles -> 1: 250,000
1: 126,720
1” = 2 miles -> 1:125,000
-------------------------1: 63,360
1” = 1 mile
-> 1:50,000
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Summary: 3 ways of showing scale:
the graphic is best on a final map
1: 16,000,000
1: 1,300,000
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