Graphics Reference
In-Depth Information
Figure
.
.
Cooperation between map view and histogram view
Figure
.
shows a tool for exploring spatial data using dynamic graphics that
wasproposedbyHaselettet al.(
)asan example of the application of cooperation
between two statistical graphs. his tool was also realized via SVG. he locations
of observation points are plotted in the “Map View” on the let, and a histogram of
the observed data is displayed in the “Histogram View” on the right. An arbitrary
region can be specified by dragging the cursor over the “Map View.” he data in the
histogramthat correspondstothelocations includedinthespecifiedregionwillthen
be overwritten on the “Histogram View.” his tool makes it possible to explore the
local variability in spatial data intuitively.
Although it is possible to realize these functions by raster graphics in a web ap-
plication, we encounter some problems if we do this using the conventional method.
It is di
cult to update part of the image dynamically with raster graphics because
the color data are associated with the individual pixels. herefore, it is necessary to
regenerate the entire imagefromthe server upona userrequest, and then display the
image on the client side. hat is, the server and the client must communicate upon
each individual user request, which leads to a decline in the operability and perfor-
mance of the web application. Because the amount of information in a rastergraphic
increases with the quality and the image size, this decline is significant. In addition,
there are portability problems in that functions such as (
) and (
) work only within
the web application; they cannot be executed in other environments. XML graphics
can solve such problems and they offer many advantages to the user and the devel-
oper. We will discuss this in more detail in the following section.
