Introduction to MapsSome Common Types of MapsA Thematic MapA Topographic MapSome Characteristics of MapsMaps and GISMaps and GISMap ScaleMap ScaleMap ProjectionsWhat Are Maps Used For?Map Design ConsiderationsMap ElementsMap ElementsUSGS Topo Map Title and ScaleMap ElementsUSGS Topo Map LegendUSGS Topo Map Textual InformationMap ElementsStudy Catchments in Suburban MarylandCoordinate GridUSGS Topo Map Coordinate GridPond Branch Catchment – Control Topographic Index ExampleMap ElementsDesign GuidelinesDesign GuidelinesDesign GuidelinesDesign GuidelinesDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Definition:•A graphic depiction on a flat medium of all or part of a geographic realm in which real world features have been replaced with symbols in their correct spatial location at a reduced scale.•To map is to transform information from one form to another --- Mathematics•Earth surface Paper --- GeographymapIntroduction to MapsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005•Reference Maps (e.g. topographic map): A map showing the outlines of selected natural and man-made features of the Earth. It also shows roads and other prominent features. (Topography = shape of the surface)•Thematic Map: A map showing the spatial patterns of a geographic theme, such as land use, climate, population etc.Some Common Types of MapsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005The darker the red fill, the greater the populationA Thematic MapWorld Population by NationDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005A Topographic MapDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005•Abstracted – requires careful interpretation•Show only static situation – a slice in time•Maps are often highly artistic: Map making is as much an art as it is a science.•Questions that are easy to answer with maps:•how to get there from here?•what is at a certain location?•Questions that are difficult to answer with maps•what is the area of this field?•what can I see from here?•what this point on the topographic map is on the thematic mapSome Characteristics of MapsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Disadvantages of Paper Maps•Consistent, accurate retrieval of data from maps is difficult•Only a limited amount of information can be shown due to the constraints of paperAdvantages of Digital Maps•Maps stored in a digital format can be rapidly accessed using a GIS:•Indexing•Remote access •GIS can produce cheap, high quality maps with high density of informationMaps and GISDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Maps and GISAdvantages of Digital Maps:•GIS allows powerful map analysis (including some analyses that are impossible with paper maps)•Accurate and rapid measurement of area•Spatial analysis•GIS offers significant advantages in map display over paper map•Browse area without boundary interruption•Zoom to change scales freely•Allows 3-D perspective viewsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Definition:The scale of a map is ratio between distances on the map and the corresponding distances in the real world.Large scale and small scale:•a large scale map shows detail, small features, e.g. 1:10,000•a small scale map shows only large features, e.g. 1:500,000Scale representation on the map:•Representative fraction: 1:100,000, 1 to 100,000, or 1/100,000•Verbal: 1 inch is equal to 50 miles•Graphic: Scale bar10 milesMap ScaleDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Map Scale• Large is Small• Small is Large1:20,000Large Scale1:500,000Small ScaleDavid Tenenbaum – GEOG 070 – UNC-CH Spring 20051:20,000Large Scale1:500,000Small ScaleDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Definition:A projection is a method by which the curved surface of the Earth is represented on a flat surface.Locationson Earth SurfaceLocationson PaperMathematicalTransformationNote: There is always some sort of distortion•Distortion is small for maps showing only small areas, and greatest when a map attempts to show the entire surface of the Earth.•Many projections have been invented, and arguments continue on which is best for what purposeMap ProjectionsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005•Navigation – maps facilitate coordinated and goal-directed route following through space•Information Display - maps provide useful ways of displaying data in a meaningful way (→ information)•Data Storage - maps are a means of data storage•Spatial Indices - maps can show the boundaries of areas (e.g. land ownership, land use types)•Data Analysis Tool - maps can be used as analytical toolse.g. to test hypotheses, such as the identification of cancer clusters by the examining the relationships using simple transparent overlaysWhat Are Maps Used For?David Tenenbaum – GEOG 070 – UNC-CH Spring 2005• Maps are a means of communication and organization of thoughts, created to transmit some spatial information to the map reader• Success or failure depends on whether or not the map communicates the intended information• Cartography as a communication system:"How do I say what to whom?" – cartographer = I– map reader/audience = whom– map design & production methods = how– subject & goals of map = whatMap Design ConsiderationsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005• Most common elements include: – map/spatial data – title – legend – scale – north arrow – inset(s) – textual information– borders & neatlines – coordinate gridMap ElementsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Title• Should be the largest and most noticeable text on the map• Be precise! No superfluous words• No "Map of..." in the title -- we know it's a mapScale• Only graphic scales will survive enlargement or reduction during reproduction • Some thematic maps may not need a scale barMap ElementsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005USGS Topo Map Title and ScaleDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Legend• Almost always required on thematic maps • Symbolization in the legend must exactly match symbolization used on the mapTextual InformationCommon uses include: • author/publisher, date of production, date of map information, projection type and coordinate system information, data sources, brief information on how the map was producedMap ElementsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005USGS Topo Map LegendDavid