CARTOGRAPHIC_OUTPUT.ppt

CARTOGRAPHIC OUTPUT
Display of Analysis
 A GIS is a means for analyzing spatial data. Cartographic
output is the means for communicating this information.
 Permanent output – printed, plotted, or stored on magnetic
tape, laser disk, etc.
 Ephemeral output - text or images that are viewed on a
CRT, overhead screen, etc.

Cartographic Output
 The principal objective of mapping.
 To create a visual image of spatial elements representing
entities interacting within some areal extent.
 General reference maps display a wide variation of spatial
information.
 Topographic map, e.g. contours of elevations, streets,
cultural divisions, waterways, grids, etc.

 Thematic maps display and represent a selected theme
(solution) or subject.
 To select, create, and place symbols and graphic
entities over a spatially defined area.
 A map is designed to be read, analyzed, and
interpreted.
 Objects displayed on a map should be necessary.

Map Conventions.
 Conflicts in map design that requires a number of
standardized decisions.
 The location of naturally-occurring physical features (a
stream or lake) takes precedence over typographical objects
(house symbols) that may not be precisely located.

The Design Process.
 Determine the visual finished map.
 Consider; the type of map to create (contour, choropleth,
dasymetric, etc.).
Objects to be included (roads, streams, lakes, cultural
features, etc), and basic layout.
 Consider symbols to be used, class limits, colors, & line
weights.

 What is the role of symbols in design?
 Ask how are point, line, and area elements discriminated?
 Size - how much area does an element take up?
 Shape – what is the geometry or shape of the element(s)?
 Hue (color).
 Value (brightness).

 Chroma (the amount of white in a hue compared to a gray
tone of the same brightness (value) level.
 Pattern is achieved by manipulating spatial entities
throughout an areal extent.
 Arrangement is a random or systematic grouping of
graphic elements.
 Texture is a spacing of graphic elements affecting
lightness or darkness.
 Orientation is a directional positioning of graphic
elements.

 Basic Design principles.
 Legibility.
 Lines must be easily separable.
 Patterns, shapes, colors, and shadings should be distinct.
 Shapes must be clear and easily identifiable.
 Sizes of objects must be appropriate for the size of the
map, and distance at which the map will be viewed.

 Visual contrast.
 Variances in brightness, colors, and shape of graphic
elements with regard to background.
 Establish a difference between the symbols themselves.
 Establish a difference between the symbols and the
background over which they are drawn.

 Figure-background.
 The ratio of figures to background.
 Balance background area with spatial entities of the map.
 Include shading, value differences, or color to establish
landwater contrast.
 Labels aid in easily identifying significant features.
 Use familiar shapes (state or county boundaries) to isolate
a study area.
 Establish good contour in which the map elements
represent a logical impression of what is on the map.

 Establish a hierarchical structure.
 Organize the graphic elements so that the important features
stand out.
 Stereogrammic method rendering graphic elements to appear
physically higher on the map.
 Changes in line width, color, shading, or size.
 Depth perception is achieved by placing objects on top of
each other.

 Extensional method (hierarchy based upon ordinal data).
 To force the important elements to stand out.
 Varying line symbols for roads, streams, etc.
 Subdivisional method (hierarchy based upon nominal data).
 Creating smaller classes.
 Using varying line widths or color and stippling to
discriminate class features.

Map Design Controls
 What is the purpose for which a map is created?
 Substantive objective, the nature of the data and information
displayed.
 Simplicity.
 Focus.
 Affective objective, or how the data are presented?
 Form of presentation.
 How to convey a message by focusing on a specific
thematic content.

 Reality, how well the limits of each mapped entity represent
itself in the map design?
 Available data.
 Select specific data germane to the analysis (thinning
excessive data).
 Variances in degree of detail, temporal variances, etc.
Operate on the “weakest link” theory.
 Scale variances.
 Smaller scale maps yield less detail per unit area.
 If using varied scaled maps in a GIS, again operate on the
“weakest link” theory.

 Audience.
 Consider the level of sophistication of the map compared to
the background of the intended audience.
 Age and ability to visually see the mapped features.
 Conditions of use - Military/field conditions, on a wall, or in a
published report.
 Technical limits.
 Hardware limits.
 Resolution, minimum mapping unit, color variance, etc.

 Nontraditional Cartographic Output
 Fishnet maps, block diagrams, and wire-frame diagrams.
 Good for visual understanding, but limited in analytical
application.
 May control the angle of view, viewing azimuth, and
viewing distance.
 Animation, coupling multiple scenes over a temporal range,
and spatially registered.
 Atmospheric conditions taken from GOES satellites.
 Fly through over terrain.

 Shaded relief maps.
 Shaded to mimic shadows.
 Good for showing relief changes and topographic
variances.
 Digital orthophotographs.
 Photogrammetrically corrected for relief displacement and
lateral shift of locations due to earth curvature, longitudinal
convergence, etc.

 Cartograms.
Graphic output with the appearance of maps, but distances,
directions, and other spatial arrangements have been modified
to illuminate specific applications.
 Route-line types, e.g. mass transit graphics or road atlases
generalizing networks using straight lines to indicate
distance and travel time between locations.
 Central-point linear types, used to modify output from a
functional (weighted) distance model.
 Distance model by difficulty.
 Frictional surface.

 Area type, in which sizes of each mapped study area are
varied.
 Contiguous, all areas are touching, although e.g. total
discharge of identified springs would result in some
locational entities (springs) being larger than others.
 Noncontiguous (exploded), areas are not touching, e.g.
conterminous U.S., and Alaska or Hawaii.

Noncartographic Output
 Maps may not provide –
 A well-understood output for its audience.
 A map is not the appropriate (desired) output medium.

Interactive Output.
 Using a GIS to determine locations of fires, and routing
scenarios for emergency (medical) routes to hospitals.
 May have both mapped and tabular output, e.g. a routing map
from point a to b, and table assigning distances and times
between ancillary locations (towns).

Tables, Charts, & Other Graphic Representations.
 Use tables to list data (attributes and records).
 May be textual material of the map legend.
 Use graphs to show a spatial distribution of numerical &
statistical data values.
 Use charts to show spatial distributions of thematic data.

 Consider a design around purpose, readability, and audience.
 Chose a font that is plain and clearly recognizable.
 Contrast tables if used within the context of a map.
 Add a boarder around tables contained within a map.
 Avoid acronyms and abbreviations.
 Be specific about data.

 Triangular graphs – soil textural relationships (clay, silt, and
sand).
 Climographs - soil moisture, precipitation, and temperature.
 Rose diagrams - showing direction and distance relationships.

 Cartesian line graphs - based upon x,y axes.
 A line connecting points of continuous observations.
 May be single series of values (temperaturepressure), or
multiple threads (temperaturepressure at different times).
 Histograms are used to show the distribution and frequency
of data.
 Bar graphs are a modification.
 Bars may also be stacked to show an additive relationship.
 Sand, silt, and clay percentages stacked in different colors
or shades (y-axis is percent), compared to different soil
series (x-axis).

Design Considerations.
 Do not use stippled patterns that are radically different
(produces eye strain and unappealing results).
 Use clear, simple symbols.
 Avoid fancy, overly stylish graphic options.
 Keep grid lines to a minimum and draw them lightly.

Technology and GIS Output.
Ephemeral output
 CRT (Cathode Ray Tube) - electron beams directed against
a phosphor-coated screen.

 Glowing results, but must be refreshed a minimum of 72
times per second (refresh rate).
 Noninterlaced CRT’s, every line is refreshed.
 Interlaced CRT’s, every other line is refreshed.
 Changes in beam intensity change gray levels or color.
 Spatial resolution is dependent on dots per inch.
 A 20” diagonal screen with a capability of displaying
1024x768 dots would require an ability to store 786,432
pixels in graphic memory per 172th second just to avoid
screen flicker.

Other Display Devices
 LCD (Liquid Crystal Display.
 LED (Light-Emitting Diode).
Permanent Output
 Ink-jet printers and plotters.
 Electrostatic printers and plotters.

CARTOGRAPHIC_OUTPUT.ppt

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