d.zoom

NAME

d.zoom - Allows the user to change the current geographic region settings interactively, with a mouse.
(GRASS Display Program)

SYNOPSIS

d.zoom
d.zoom help
d.zoom [-q] [action=name]

DESCRIPTION

d.zoom allows the user to interactively adjust the settings of the current geographic region using a pointing device such as a mouse. Like g.region, d.zoom re-defines the settings of the geographic region. However, d.zoom allows the user to change the current region settings interactively, by either outlining the new region perimeter with a mouse or "rotating" latitude-longitude data into the current region. The user should run d.erase after d.zoom is run for the new region settings to affect the graphics display.

OPTIONS

Flag:

-q: Run quietly, suppressing output of some program messages to standard output.

Parameter:

action=name: Allows the user to change the geographic region settings by "rotating" the globe to move a different portion of the globe into the stationery boxed region outline (making this new portion of the globe the new current region), rather than by moving the boxed region outline. This option can only be used with latitude-longitude data bases (although d.zoom will not complain if the user attempts to set this parameter while running on a non-latitude-longitude data base).
Options: zoom, rotate

After the user types the command d.zoom and (optionally) sets the -q flag and type of zoom to be performed, a mouse-button menu will appear, directing the user to: establish the corners of the new geographic region, check its coordinates, and confirm any changes made. When the user accepts new geographic boundaries, d.zoom asks,

Accept new region? Y / N >

If the user clicks the mouse over the "Y" (yes), the mouse-drawn geographic region is saved as the user's current geographic region. The user is warned that d.erase should be run after d.zoom to make new current region settings affect the graphics display.

If the user clicks the mouse over the "N" (no), the first mouse-drawn geographic region is not saved; instead, d.zoom asks whether or not the user wishes to

Try Again? Y / N >

The user can then opt to draw a new region with the mouse ("Y"), or opt to exit d.zoom ("N") and leave current region settings unchanged.

To zoom-out to a larger area than was windowed-in on with d.zoom (i.e., to enlarge the current geographic region), the user may run g.region. The user may also alter the current geographic region by running the "region" option of the d.display program.

NOTES

Although it is not necessary that the user display a map in the active display frame before running d.zoom, it is helpful to do this for reference.

Currently, the rubber-banded boundaries of the zoom region drawn by the user are not clearly visible on the graphics monitor. However, whether or not these boundaries are clearly visible when drawn, the drawn region is still correctly zoomed-in on.

AUTHOR

Michael Shapiro, U.S. Army Construction Engineering Research Laboratory