## NAME

nviz - Visualization and animation tool for GRASS data

## SYNOPSIS

nviz
nviz [-q] [path=dir] [elevation=name [ ,name,... ]] [vector=name [ ,name,... ]] [sites=name [ ,name,... ]]

## DESCRIPTION

nviz organizes several useful tools for combining and visualizing GRASS raster, vector and site files. In particular, nviz provides a detailed user interface with several panels used for specifying various options. The user may specify arbitrary combinations of raster maps, vector maps, and site maps. The attributes associated with each map (such as color, masking, line width, etc.) may be modified independently. Also, cut-planes may be used to display an interpolated cross section of a set of raster maps. nviz emphasizes a flexible and natural viewing mechanism allowing the user to modify view parameters such as camera position, surface exaggeration, display resolution, lighting models, and light position. Lastly, nviz supports an animation and scripting mechanism for building visualizations of sequences of GRASS data. The scripting mechanism may be used to record and playback any user session. Other miscellaneous features include: a facility for querying map displays for information, and image processing tools which allow the placement of labels and scales on the display.

## OPTIONS

The initial set of files used by nviz may be specified by providing file arguments for elevation, vector and sites. If the user specifies program arguments on the command line, the program will start with the given set of files. Alternatively, the user can simply type nviz on the command line and the program will ask for parameter values and flag settings interactively, using the standard GRASS parser interface.

### Flag:

-q
  Quickstart. Skip over the usual GRASS parser interface and start nviz. Ignores any file parameters which may have been specified on the command line.

### Parameters:

path=dir
  Search for additional panels in the specified directory.
elevation=name[,name,...]
  Use the given list of existing raster files as input.
vector=name[,name,...]
  Use the given list of existing vector files as input.
sites=name[,name,...]
  Use the given list of existing sites files as input.

## PANELS

nviz features are presented to the user using "panels". A panel encapsulates some functionality and provides an interface for users to access this functionality. For example, nviz is distributed with panels for manipulating surfaces, vector files, light sources, and so on. In addition to these default panels, nviz may also be configured to load application specific panels.

In addition to the default panels, nviz can be instructed to load additional panels by either using the path option (see above) or by setting the GRASS resource NvizPanelPath to the appropriate list of directories. Any directory specified as a path directory must contain a panelIndex file which names the panels stored in that directory. Panel creation and panelIndex files are described elsewhere.

## GRASS RESOURCE SETTINGS

NvizPanelPath
  Specifies a list of directories containing additional panels (see PANELS).
NvizAutoSurfColors
  If set to true then any surface loaded from the surface panel will have the color attribute set to the map used to specify topology. This is the default behavior.

## NOTES

Currently, nviz must be invoked from within GRASS (preferably version 5.x). That is, start GRASS then invoke nviz from the GRASS shell.

nviz is built on top of the Tcl/Tk environment. Be sure you have at least Tcl 8.0 or later and Tk 8.0 or later and that appropriate environment variables are set correctly.

## DIAGNOSTICS

ERROR: LOCATIONNAME not set
The program was run outside of GRASS.

TclAppInit failed: can't find /usr/local/lib/tcl/init.tcl; perhaps you need to install Tcl or set your TCLLIBRARY environment variable?
Tcl not installed correctly or TCLLIBRARY environment variable not set correctly.

TclAppInit failed: can't find /usr/local/lib/tk/tk.tcl; perhaps you need to install Tk or set your TKLIBRARY environment variable?
Tk not installed correctly or TKLIBRARY environment variable not set correctly.

Usage: nviz [-q] [elevation=name[,name,...]] [vector=name[,name,...]] [sites=name[,name,...]]
Invalid options were specified on the command line.

## SEE ALSO

SG3d

## AUTHORS

Original program (Sg3d(NASA Panels) and Nviz(Motif) versions):
David Gerdes, Bill Brown, and Helena Mitasova, U.S. Army CERL.

Current version (Tcl/Tk version):
Bill Brown, David Gerdes, Helena Mitasova, Terry Baker, and Mark Astley, U.S. Army CERL.
Various members of the GRASS community have provided suggestions throughout the duration of the project.

Last changed: $Date: 2002/01/25 05:45:33 $