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       Note:  wxGUI 3D view mode is currently under development. It's provided as an experimental

       wxNviz is a wxGUI 3D view  mode  which  allows  users  to  realistically  render  multiple
       surfaces  (raster  data)  in  a  3D  space, optionally using thematic coloring, draping 2D
       vector data over the surfaces, displaying 3D vector data in the space,  and  visualization
       of volume data (3D raster data).

       To  start  the  wxGUI  3D view mode, choose '3D view' from the map toolbar. You can switch
       between 2D and 3D view. The region in 3D view is updated according to displayed region  in
       2D view.

       wxNviz  is emphasized on the ease and speed of viewer positioning and provided flexibility
       for using a wide range of data. A low resolution surface or wire grid (optional)  provides
       real-time  viewer  positioning capabilities. Coarse and fine resolution controls allow the
       user to further refine drawing speed and detail as needed. Continuous scaling of elevation
       provides the ability to use various data types for the vertical dimension.

       For  each  session of wxNviz, you might want the same set of 2D/3D raster and vector data,
       view parameters, or other attributes. For consistency between sessions, you can store this
       information  in  the GRASS workspace file (gxw). Workspace contains information to restore
       "state" of the system in 2D and if wxNviz is enabled also in the 3D display mode.

3D View Toolbar

        Generate command for m.nviz.image
           Generate command for m.nviz.image based on current state.

        Show 3D view mode settings
           Show dialog with settings for wxGUI 3D view mode. The user settings can be  stored  in
           wxGUI settings file.

        Show help
           Show this help.

3D View Layer Manager Toolbox

       The 3D view toolbox is integrated in the Layer Manager. The toolbox has several tabs:

                     View for view controlling,

                     Data for data properties,

                     Appearance for appearance settings (lighting, fringes, ...).

                     Analysis for various data analyses (only cutting planes so far).

                     Animation for creating simple animations.

       You  can  use  this panel to set the position, direction, and perspective of the view. The
       position box shows a puck with a direction line pointing to the center. The direction line
       indicates  the look direction (azimuth). You click and drag the puck to change the current
       eye position. Another way to change eye position  is  to  press  the  buttons  around  the
       position box representing cardinal and ordinal directions.

       There are four other buttons for view control in the bottom of this panel (following label

                     here requires you to click on Map Display Window to determine the  point  to
                     look at.

                     center changes the point you are looking at to the center.

                     top moves the current eye position above the map center.

                     reset returns all current view settings to their default values.
       You  can adjust the viewer's height above the scene, perspective and twist value to rotate
       the scene about the horizontal axis. An angle of 0 is flat. The scene rotates between  -90
       and 90 degrees.

       You  can  also  adjusts  the  vertical  exaggeration of the surface. As an example, if the
       easting and northing are in meters and the elevation in feet, a vertical  exaggeration  of
       0.305 would produce a true (unexaggerated) surface.

       View  parameters  can  be  controlled  by  sliders  or  edited directly in text box.  It's
       possible to enter values which are out of slider's range (and it will adjust then).

   Fly-through mode
       View can be changed in fly-through mode (can be activated in Map Display  toolbar),  which
       enables  to  change  the view smoothly and therefore it is suitable for creating animation
       (see below). To start flying, press left mouse button and hold it down to continue flying.
       Flight  direction  is  controlled  by mouse cursor position on screen. Flight speed can be
       increased/decreased stepwise by keys PageUp/PageDown, Home/End or Up/Down  arrows.   Speed
       is  increased  multiple times while Shift key is held down. Holding down Ctrl key switches
       flight mode in the way that position of viewpoint is changed (not the direction).

   Data properties
       This tab controls the parameters related to map layers. It consists  of  four  collapsible
       panels - Surface, Constant surface, Vector and Volume.

       Each active raster map layer from the current layer tree is displayed as surface in the 3D
       space. This panel controls how loaded surfaces are  drawn.   To  change  parameters  of  a
       surface, it must be selected in the very top part of the panel.

       The  top half of the panel has drawing style options.  Surface can be drawn as a wire mesh
       or using filled polygons (most realistic). You can set draw mode to coarse  (fast  display
       mode),  fine  (draws  surface  as  filled  polygons  with  fine resolution) or both (which
       combines coarse and fine mode). Additionally set coarse style to wire to draw the  surface
       as  wire mesh (you can also choose color of the wire) or surface to draw the surface using
       coarse resolution filled polygons. This is a low resolution version of the polygon surface
       style.   E.g. surface is drawn as a wire mesh if you set mode to coarse and style to wire.
       Note that it differs from the mesh drawn in fast display mode because hidden lines are not
       drawn.  To  draw  the  surface  using  filled polygons, but with wire mesh draped over it,
       choose mode both and style wire.  Beside mode and style  you  can  also  choose  style  of
       shading  used  for  the surface. Gouraud style draws the surfaces with a smooth shading to
       blend individual cell colors together, flat draws the surfaces with flat shading with  one
       color for every two cells. The surface appears faceted.

       To set given draw settings for all loaded surfaces press button "Set to all".

       The bottom half of the panel has options to set, unset or modify attributes of the current
       surface. Separate raster data or constants can be  used  for  various  attributes  of  the

                     color - raster map or constant color to drape over the current surface. This
                     option is useful for draping imagery such as aerial photography over a DEM.

                     mask - raster map  that  controls  the  areas  displayed  from  the  current

                     transparency  -  raster map or constant value that controls the transparency
                     of the current surface. The default  is  completely  opaque.  Range  from  0
                     (opaque) to 100 (transparent).

                     shininess  -  raster  map  or  constant  value  that  controls the shininess
                     (reflectivity) of the current surface. Range from 0 to 100.

       In the very bottom part of the panel position of surface can be set.  To move the  surface
       right  (looking  from  the  south) choose X axis and set some positive value. To reset the
       surface position press Reset button.

   Constant surface
       It is possible to add constant surface and set its properties like fine resolution,  value
       (height), color and transparency. It behaves similarly to surface but it has less options.

       2D  vector  data  can be draped on the selected surfaces with various markers to represent
       point data; you can use attribute of vector features to determine size,  color,  shape  of
       glyph.  3D vector data including volumes (closed group of faces with one kernel inside) is
       also supported.  This panel controls how loaded 2D or 3D vector data are drawn.

       You can define the width (in pixels) of the line features, the color  used  for  lines  or
       point markers.

       If  vector  map  is 2D you can display vector features as flat at a specified elevation or
       drape it over a surface(s) at a specified height. Use the height control to set  the  flat
       elevation  or  the  drape  height above the surface(s). In case of multiple surfaces it is
       possible to specify which surfaces is the vector map draped over.

       For display purposes, it is better to set the height slightly above the  surface.  If  the
       height is set at zero, portions of the vector may disappear into the surface(s).

       For  2D/3D  vector  points  you  can  also  set  the  size  of the markers.  Currently are
       implemented these markers:

                     x sets the current points markers to a 2D "X",

                     sphere - solid 3D sphere,

                     diamond - solid 3D diamond,

                     cube - solid 3D cube,

                     box - hollow 3D cube,

                     gyroscope - hollow 3D sphere,

                     asterisk - 3D line-star.

       Thematic mapping can be used to determine marker  color  and  size  (and  line  color  and

       Volumes  (3D  raster maps) can be displayed either as isosurfaces or slices.  Similarly to
       surface panel you can define draw shading - gouraud  (draws  the  volumes  with  a  smooth
       shading  to  blend  individual cell colors together) and flat (draws the volumes with flat
       shading with one color for every two cells. The  volume  appears  faceted).  As  mentioned
       above currently are supported two visualization modes:

                     isosurface - the levels of values for drawing the volume(s) as isosurfaces,

                     and slice -  drawing the volume as cross-sections.

       The middle part of the panel has controls to add, delete, move up/down selected isosurface
       or slice. The bottom part differs for isosurface and  slice.   When  choosing  isosurface,
       this  part  the  of  panel  has  options to set, unset or modify attributes of the current
       isosurface.  Various attributes of the isosurface can be  defined,  similarly  to  surface

                     isosurface value - reference isosurface value (height in map units).

                     color - raster map or constant color to drape over the current volume.

                     mask - raster map that controls the areas displayed from the current volume.

                     transparency  -  raster map or constant value that controls the transparency
                     of the current volume. The  default  is  completely  opaque.  Range  from  0
                     (opaque) to 100 (transparent).

                     shininess  -  raster  map  or  constant  value  that  controls the shininess
                     (reflectivity) of the current volume. Range from 0 to 100.
       In case of volume slice the bottom part of the panel controls the slice attributes  (which
       axis  is  slice parallel to, position of slice edges, transparency). Press button Reset to
       reset slice position attributes.

       Volumes can be moved the same way like surfaces do.

       Analysis tab contains Cutting planes panel.

   Cutting planes
       Cutting planes allow to cut surfaces along a plane. You can switch between six planes;  to
       disable cutting planes switch to None.  Initially the plane is vertical, you can change it
       to horizontal by setting tilt 90 degrees. The X and Y values specify the  rotation  center
       of plane. You can see better what X and Y do when changing rotation.  Height parameter has
       sense only when changing tilt too. Press button Reset to reset current cutting plane.

       In case of multiple surfaces you can visualize the cutting plane by  Shading.  Shading  is
       visible  only  when  more than one surface is loaded and these surfaces must have the same
       fine resolution set.

       Appearance tab consists of three collapsible panels:

                     Lighting for adjusting light source

                     Fringe for drawing fringes

                     Decorations to display north arrow and scale bar

       The lighting panel enables to change the position of light source, light color, brightness
       and  ambient. Light position is controlled similarly to eye position. If option Show light
       model is enabled light model is displayed to visualize the light settings.

       The Fringe panel allows you to draw fringes in different directions (North & East, South &
       East,  South  &  West, North & West). It is possible to set fringe color and height of the
       bottom edge.

       The Decorations panel enables to display north arrow and simple scale bar. North arrow and
       scale bar length is determined in map units.  You can display more than one scale bar.

       Animation  panel  enables  to  create  a  simple animation as a sequence of images.  Press
       'Record' button and start changing the view. Views are recorded in given interval  (FPS  -
       Frames Per Second). After recording, the animation can be replayed. To save the animation,
       fill in the directory and file prefix, choose image format (PPM or  TIF)  and  then  press
       'Save'.  Now  wait  until  the  last  image  is  generated.   It  is recommended to record
       animations using fly-through mode to achieve smooth motion.


       This panel has controls which allows user to set default surface, vector and  volume  data
       attributes. You can also modify default view parameters, or to set the background color of
       the Map Display Window (the default color is white).

To be implemented

                     Labels, decoration, etc. (Implemented, but not fully functional)

                     Surface - mask by zero/elevation, more interactive positioning

                     Vector points - implement display mode flat/surface for 2D points


       wxNviz is under active development and distributed as "Experimental Prototype".

       Please note that with wxGTK port of wxPython  (Linux  systems),  a  problem  might  appear
       during  wxNviz  initialization (nothing is rendered at all) or when rendering vectors (bad
       order of rendering surfaces and vectors). If you encounter such problems, try to change  a
       depth  buffer number in GUI Settings > Map Display > Advanced (possible numbers are 0, 16,
       24, 32). It is currently not possible to automatically find out the right number which  is
       working for your computer.


       wxGUI components

       See also wiki page (especially various video tutorials).
       Command-line module m.nviz.image.
       Original Tcl/Tk-based NVIZ.


       The wxNviz GUI

       Martin Landa, Google Summer of Code 2008 (mentor: Michael Barton) and 2010 (mentor: Helena
       Anna Kratochvilova, Google Summer of Code 2011 (mentor: Martin Landa)

       The OGSF library and NVIZ engine

       NVIZ (GRASS's n-dimensional visualization suite) was written by Bill Brown,  Terry  Baker,
       Mark  Astley,  and  David  Gerdes,  U.S.  Army  Corps  of Engineers Research Laboratories,
       Champaign, Illinois and UI GMS Laboratory, Urbana, IL in the early 1990s.

       Original documentation was written by Terry Baker  (spring  1995),  and  updated  by  Mark
       Astley,  based on a document written by Bill Brown.  Additional design help and funding in
       the early 1990s by Helena Mitasova (CERL). Tcl/Tk support added by Terry Baker. Ported  to
       Linux  by  Jaro  Hofierka and others. Conversion from SGI IRIS GL code to OpenGL by Justin
       Hickey. Further program and documentation (2004) updates by Bob Covill, Tekmap Consulting.
       3D  volume  support  by  Tomas  Paudits  with  supervision  from  Jaro Hofierka and Helena
       Mitasova.  Fly-through mode, thematic site attributes, and picking by Massimo Cuomo  (ACS)
       with updates by Michael Barton. GRASS 6 vector support by Radim Blazek. Additional updates
       by Markus Neteler, Martin Landa, Glynn Clements, and Hamish Bowman.

       NVIZ evolved from the earlier GRASS program SG3d written for Silicon Graphics IRIS  GL  by
       Bill  Brown and Dave Gerdes at USA CERL, 1990-1995 and from the NVIZ Motif version written
       by Bill Brown with contributions by Terrance McGhee.

       $Date: 2013-06-23 22:16:03 +0200 (Sun, 23 Jun 2013) $

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