Cartogram maps display
variables by varying area size. MapViewer's
can create Dorling, contiguous, and noncontiguous cartograms. In a Dorling
cartogram the areas are replaced by circles and the circles are scaled
according to a variable. The maps can be controlled so the circles do
not overlap and are positioned as close to the base map's centroids as
possible. In a noncontiguous cartogram, polygon shapes are disconnected,
and the area is proportional to the selected variable. In a contiguous
cartogram, polygons remain connected, and their size and shape are distorted
as the area is scaled to the selected variable.
Click the Map | Create Map |
Cartogram command to
create a cartogram map. Edit cartogram map properties in the Property
Manager.
See Creating and Editing Thematic Maps for information on creating a map, changing a map to another map type, and changing map properties.
The cartogram map Property Manager has General, Data Labels, Info, and Map pages. Click the preceding hyperlinks for information on properties in each of the property manager pages.
Select cartogram type and edit cartogram specific properties in the Map page of the Property Manager.
Edit cartogram map properties in the Map page of the Property Manager.
The General section properties select the cartogram type and edit the cartogram map. Click the Cartogram type list to select a Dorling, Non-contiguous, or Contiguous cartogram.
Generating a contiguous cartogram map can take a few seconds, depending on the cartogram map settings, data set, and your computer's capabilities. Unlike other gridding operations, contiguous cartogram map creation cannot be cancelled.
The Leaping force controls
the distance the circles or polygons move in each convergence pass. The
circles or polygons move away from the previous position with each pass.
Type a value between 0.01 and 1.00 in the Leaping
force field or click the
buttons to set the Leaping force.
A Leaping force of 1.0
moves the circle far away from the previous position with each pass. A
Leaping force of 0.01moves the
circles very little with each pass. Dorling
and Non-contiguous
cartograms have the Leaping force
property.
The A/R ratio is the attraction/repulsion
ratio that controls circle or polygon overlap. Type a value between 0.01
and 1.00 in the A/R ratio field
or click the buttons
to set the A/R ratio. An A/R ratio of 1.0 makes the circles
overlap each other. An A/R Ratio
of 0.01 leads to minimum overlap. Dorling
and Non-contiguous cartograms
have the A/R ratio
property.
Convergence passes controls the number of times the circles are repositioned with the Leaping force and A/R ratio values. Only Dorling cartograms have the Convergence passes property.
Click the Defaluts button in the Default settings field to return the cartogram to the MapViewer defaults. Only Dorling and Non-contiguous cartograms have the Defalut settings option.
Set the line properties for the cartogram map in the Line section. See the line properties help page for more information on editing cartogram line properties.
Set the cartogram fill properties in the Fill
section. See the fill
properties help page for more information on editing cartogram map
fill properties. Apply a gradient fill to the cartogram map by selecting
Linear or Radial
from the Type list. Click on
the Colormap selection to pick
a predefined colormap for the gradient, or click the
button to create a custom colormap in the Colormap
dialog. Select a Vertical, Horizontal, Inward,
or Outward gradient direction
in the Gradient Direction list.
See Also