The user interface is composed of a tree hierarchy of windows,
called telewindows (or telewin, for short). Each telewin can have
multiple children, and the user has control over opening and closing
telewins. (Only leaves of the tree can be closed). A child telewin
shows a more zoomed in view of the geography than its parent. If the
portions of the geography shown in the child and parent overlap,
then a black rectangle in the parent indicates the
location of the child. All the telewindows are placed inside a
window called the Applet Panel. The telewindows
can be resized and moved within the Applet Panel.
The first telewindow is called the Root Window.
It shows the entire map in the lowest detail,
and it has special restrictions: no zooming,
panning, resizing, or closing. (It may be iconified.)
You can get help from within the program by pressing the
question mark button. Here is a summary of the basic
operations.
Open a new telewin as the child of an existing telewin by
right-clicking the mouse on the existing telewin.
Close a telewin with the standard close icon in
the upper right corner.
Detach or attach (let the applet panel
float or fix the applet panel to the
browser).
Pan (translate the view in a telewin) by
dragging with the left mouse button.
Zoom in or out in a telewin by clicking the
buttons, or by moving the slider.
Jump to a new location by clicking on
that location in the parent telewin.
Center a telewin's parent at the telewin's
own center by clicking on the button.
Feature labels pop up when the mouse
pauses over a feature; labels can be
turned off from the Options menu.
Teleport -- which lists
locations that you can directly jump to.
My Places -- you can enter
your own favorite sites and this will be
remembered for the future. [Note: we
may post your favorite sites for other
users to visit.]
Additional Information:
The scale of a telewindow is given above
the slider. The bar shown is equivalent
to the number of meters or kilometers
shown. The smallest scale (i.e. highest
detail) is 250 meters per 100 pixels.
There are several levels of detail, and
these are indicated by the color bar under
the slider. Zooming in or out within a
particular color only changes the size of
the features shown; zooming in or out to
a different color on the color bar changes
the actual set of features shown.
Each telewindow always has a smaller scale
than its parent. When zooming, the scales
on multiple telewindows might change to
insure that this condition is always true.
At the bottom of the applet panel, on the left
side, are five letters that are either red,
for "on", or gray, for "off". These letters
represent various states that the program can
be in.
'W' indicates the program is waiting for
data from the server.
'L' indicates that data is currently being
loaded from the network.
'U' indicates that a data block previously
loaded is being unpacked (uncompressed and
processed for local display).
'P' indicates that local data is being
prepared for rendering to the screen.
'R' indicates that screen rendering is
currently being done.
Also at the bottom of the applet panel is an
ongoing display of the cumulative data
transmission:
bytes transmitted so far
additional bytes that would have been transmitted if
compression had not been used (e.g., "(+9546)")
number of points transmitted
number of polylines transmitted
number of polygons transmitted
The numbers for polylines and polygons
are for processed data, not the raw
TIGER data.
Initially, the applet only loads the data that is actually displayed.
As you pan around, the data for displaying the new areas is
dynamically loaded from the server. We are working on the design and
implementation of techniques that will greatly speed up this process.