1wxGUI.nviz(1)               GRASS GIS User's Manual              wxGUI.nviz(1)
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wxGUI 3D View Mode

KEYWORDS

7       display, GUI, visualization, graphics, raster, vector, raster3d
8

DESCRIPTION

10       Note:  wxNviz is currently under development. Not all planned function‐
11       ality is already implemented.
12
13       wxNviz is a wxGUI 3D view mode which allows users to realistically ren‐
14       der  multiple surfaces (2D raster maps) in a 3D space, optionally using
15       thematic coloring, draping 2D vector data or different 2D  raster  data
16       over  the surfaces, displaying 3D vector data in the space, and visual‐
17       ization of 3D rasters.
18
19       To start the wxGUI 3D view mode, choose ’3D view’ from the map toolbar.
20       You can switch between 2D and 3D view. The region in 3D view is updated
21       according to displayed region in 2D view.
22
23       wxNviz is emphasized on the ease and speed of  viewer  positioning  and
24       provided  flexibility  for using a wide range of data. A low resolution
25       surface or wire grid (optional) provides real-time  viewer  positioning
26       capabilities.  Coarse  and  fine  resolution controls allow the user to
27       further refine drawing speed and detail as needed.  Continuous  scaling
28       of  elevation  provides  the  ability to use various data types for the
29       vertical dimension.
30
31       For each session of wxNviz, you might want the same set of 2D/3D raster
32       and  vector data, view parameters, or other attributes. For consistency
33       between sessions, you can store this information in the GRASS workspace
34       file  (gxw).  Workspace  contains information to restore "state" of the
35       system in 2D and if wxNviz is enabled also in the 3D display mode.
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3D View Toolbar

38             Generate command for m.nviz.image
39           Generate command for m.nviz.image based on current state.
40
41             Show 3D view mode settings
42           Show dialog with settings for wxGUI 3D view mode. The user settings
43           can be stored in wxGUI settings file.
44
45             Show help
46           Show this help.
47

3D View Layer Manager Toolbox

49       The 3D view toolbox is integrated in the Layer Manager. The toolbox has
50       several tabs:
51
52View for view controlling,
53
54Data for data properties,
55
56Appearance for appearance settings (lighting, fringes, ...).
57
58Analysis for various data  analyses  (only  cutting  planes  so
59               far).
60
61Animation for creating simple animations.
62
63   View
64       You  can use this panel to set the position, direction, and perspective
65       of the view. The position box shows a puck with a direction line point‐
66       ing to the center. The direction line indicates the look direction (az‐
67       imuth). You click and drag the puck to change the current eye position.
68       Another  way  to change eye position is to press the buttons around the
69       position box representing cardinal and ordinal directions.
70
71       There are four other buttons for view control in  the  bottom  of  this
72       panel (following label Look:):
73
74here  requires  you to click on Map Display Window to determine
75               the point to look at.
76
77center changes the point you are looking at to the center.
78
79top moves the current eye position above the map center.
80
81reset returns all current view settings to their  default  val‐
82               ues.
83       You  can  adjust  the  viewer’s height above the scene, perspective and
84       twist value to rotate the scene about the horizontal axis. An angle  of
85       0 is flat. The scene rotates between -90 and 90 degrees.
86
87       You  can  also  adjusts the vertical exaggeration of the surface. As an
88       example, if the easting and northing are in meters and the elevation in
89       feet, a vertical exaggeration of 0.305 would produce a true (unexagger‐
90       ated) surface.
91
92       View parameters can be controlled by sliders or edited directly in  the
93       text  boxes.  It  is possible to enter values which are out of slider’s
94       range (and it will then adjust to the new range).
95
96   Fly-through mode
97       View can be changed in fly-through mode (can be activated in  Map  Dis‐
98       play  toolbar), which enables to change the view smoothly and therefore
99       it is suitable for creating animation (see  below).  To  start  flying,
100       press left mouse button and hold it down to continue flying. Flight di‐
101       rection is controlled by mouse cursor position on screen. Flight  speed
102       can  be  increased/decreased stepwise by keys PageUp/PageDown, Home/End
103       or Up/Down arrows. Speed is increased multiple times while Shift key is
104       held  down.  Holding down Ctrl key switches flight mode in the way that
105       position of viewpoint is changed (not the direction).
106
107   Data properties
108       This tab controls the parameters related to map layers. It consists  of
109       four  collapsible  panels  -  Surface,  Constant surface, Vector and 3D
110       raster.
111
112   Surface
113       Each active raster map layer from the current layer tree  is  displayed
114       as surface in the 3D space. This panel controls how loaded surfaces are
115       drawn. To change parameters of a surface, it must be  selected  in  the
116       very top part of the panel.
117
118       The  top  half  of the panel has drawing style options.  Surface can be
119       drawn as a wire mesh or using filled polygons (most realistic). You can
120       set  draw  mode  to  coarse (fast display mode), fine (draws surface as
121       filled polygons with fine resolution) or both  (which  combines  coarse
122       and  fine mode). Additionally set coarse style to wire to draw the sur‐
123       face as wire mesh (you can also choose color of the wire) or surface to
124       draw the surface using coarse resolution filled polygons. This is a low
125       resolution version of the polygon surface style.  E.g. surface is drawn
126       as  a  wire mesh if you set mode to coarse and style to wire. Note that
127       it differs from the mesh drawn in  fast  display  mode  because  hidden
128       lines  are  not  drawn.  To draw the surface using filled polygons, but
129       with wire mesh draped over it, choose mode both and style wire.  Beside
130       mode  and  style you can also choose style of shading used for the sur‐
131       face. Gouraud style draws the surfaces with a smooth shading  to  blend
132       individual  cell  colors  together,  flat  draws the surfaces with flat
133       shading with one  color  for  every  two  cells.  The  surface  appears
134       faceted.
135
136       To set given draw settings for all loaded surfaces press button "Set to
137       all".
138
139       The bottom half of the panel has options to set, unset  or  modify  at‐
140       tributes  of the current surface. Separate raster data or constants can
141       be used for various attributes of the surface:
142
143color - raster map or constant color to drape over the  current
144               surface.  This  option  is  useful  for draping imagery such as
145               aerial photography over a DEM.
146
147mask - raster map that controls the areas  displayed  from  the
148               current surface.
149
150transparency  -  raster map or constant value that controls the
151               transparency of the current surface. The default is  completely
152               opaque. Range from 0 (opaque) to 100 (transparent).
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154shininess  -  raster  map  or  constant value that controls the
155               shininess (reflectivity) of the current surface. Range  from  0
156               to 100.
157
158       In  the  very  bottom part of the panel position of surface can be set.
159       To move the surface right (looking from the south) choose  X  axis  and
160       set some positive value. To reset the surface position press Reset but‐
161       ton.
162
163   Constant surface
164       It is possible to add constant surface and set its properties like fine
165       resolution,  value  (height),  color and transparency. It behaves simi‐
166       larly to surface but it has less options.
167
168   Vector
169       2D vector data can be draped on  the  selected  surfaces  with  various
170       markers  to  represent point data; you can use attribute of vector fea‐
171       tures to determine size, color, shape of glyph.  3D vector data includ‐
172       ing volumes (closed group of faces with one kernel inside) is also sup‐
173       ported.  This panel controls how loaded 2D or 3D vector data are drawn.
174
175       You can define the width (in pixels) of the line  features,  the  color
176       used for lines or point markers.
177
178       If vector map is 2D you can display vector features as flat at a speci‐
179       fied elevation or drape it over a surface(s) at a specified height. Use
180       the  height control to set the flat elevation or the drape height above
181       the surface(s). In case of multiple surfaces it is possible to  specify
182       which surfaces is the vector map draped over.
183
184       For display purposes, it is better to set the height slightly above the
185       surface. If the height is set at zero, portions of the vector may  dis‐
186       appear into the surface(s).
187
188       For 2D/3D vector points you can also set the size of the markers.  Cur‐
189       rently are implemented these markers:
190
191x sets the current points markers to a 2D "X",
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193sphere - solid 3D sphere,
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195diamond - solid 3D diamond,
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197cube - solid 3D cube,
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199box - hollow 3D cube,
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201gyroscope - hollow 3D sphere,
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203asterisk - 3D line-star.
204
205       Thematic mapping can be used to determine marker color  and  size  (and
206       line color and width).
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208   3D rasters
209       3D  raster maps (volumes, voxel models) can be displayed either as iso‐
210       surfaces or slices.  Similarly to surface panel  you  can  define  draw
211       shading  - gouraud (draws the 3D rasters with a smooth shading to blend
212       individual cell colors together) and flat (draws the  3D  rasters  with
213       flat  shading with one color for every two cells. The 3D raster appears
214       faceted). As mentioned above currently are supported two  visualization
215       modes:
216
217isosurface  - the levels of values for drawing the 3D raster(s)
218               as isosurfaces,
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220           •   and slice -  drawing the 3D raster as cross-sections.
221
222       The middle part of the panel has controls to add, delete, move  up/down
223       selected   isosurface  or slice. The bottom part differs for isosurface
224       and slice.  When choosing an isosurface, this part the of panel has op‐
225       tions  to  set,  unset  or modify attributes of the current isosurface.
226       Various attributes of the isosurface can be defined, similarly to  sur‐
227       face attributes:
228
229isosurface  value  -  reference isosurface value (height in map
230               units).
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232color - raster map or constant color to drape over the  current
233               3D raster.
234
235mask  -  raster  map that controls the areas displayed from the
236               current 3D raster.
237
238transparency - raster map or constant value that  controls  the
239               transparency  of  the  current  3D  raster. The default is com‐
240               pletely opaque. Range from 0 (opaque) to 100 (transparent).
241
242shininess - raster map or  constant  value  that  controls  the
243               shininess (reflectivity) of the current 3D raster. Range from 0
244               to 100.
245       In case of 3D raster slice the bottom part of the  panel  controls  the
246       slice  attributes  (which  axis is slice parallel to, position of slice
247       edges, transparency). Press button Reset to reset  slice  position  at‐
248       tributes.
249
250       3D rasters can be moved the same way like surfaces do.
251
252   Analysis
253       Analysis tab contains Cutting planes panel.
254
255   Cutting planes
256       Cutting planes allow cutting surfaces along a plane. You can switch be‐
257       tween six planes; to disable cutting planes switch to None.   Initially
258       the  plane is vertical, you can change it to horizontal by setting tilt
259       90 degrees. The X and Y values specify the rotation  center  of  plane.
260       You  can see better what X and Y do when changing rotation.  The Height
261       parameter applies only when changing tilt concurrently.  Press the  Re‐
262       set button to reset the current cutting plane.
263
264       In  case  of  multiple  surfaces you can visualize the cutting plane by
265       Shading. Shading is visible only when more than one surface  is  loaded
266       and these surfaces must have the same fine resolution set.
267
268   Appearance
269       Appearance tab consists of three collapsible panels:
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271Lighting for adjusting light source
272
273Fringe for drawing fringes
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275Decorations to display north arrow and scale bar
276
277       The  lighting  panel  enables  to  change the position of light source,
278       light color, brightness and ambient. Light position is controlled simi‐
279       larly  to  eye  position.  If  option Show light model is enabled light
280       model is displayed to visualize the light settings.
281
282       The Fringe panel allows you to draw  fringes  in  different  directions
283       (North  & East, South & East, South & West, North & West). It is possi‐
284       ble to set the fringe color and height of the bottom edge.
285
286       The Decorations panel enables to display north arrow and  simple  scale
287       bar.  North arrow and scale bar length is determined in map units.  You
288       can display more than one scale bar.
289
290   Animation
291       Animation panel enables to create a simple animation as a  sequence  of
292       images.  Press  ’Record’  button and start changing the view. Views are
293       recorded in given interval (FPS - Frames Per Second). After  recording,
294       the  animation  can be replayed. To save the animation, fill in the di‐
295       rectory and file prefix, choose image format  (PPM  or  TIF)  and  then
296       press  ’Save’.  Now wait until the last image is generated.  It is rec‐
297       ommended to record animations using fly-through mode to achieve  smooth
298       motion.
299

Settings

301       This  panel has controls which allows user to set default surface, vec‐
302       tor and 3D raster data attributes. You can also modify default view pa‐
303       rameters, or to set the background color of the Map Display Window (the
304       default color is white).
305

To be implemented

307           •   Labels, decoration, etc.  (Implemented,  but  not  fully  func‐
308               tional)
309
310           •   Surface - mask by zero/elevation, more interactive positioning
311
312           •   Vector  points  -  implement  display  mode flat/surface for 2D
313               points
314
315           •   ...
316

NOTE

318       wxNviz is under active development  and  distributed  as  "Experimental
319       Prototype".
320
321       Please note that with wxGTK port of wxPython (Linux systems), a problem
322       might appear during wxNviz initialization (nothing is rendered at  all)
323       or  when  rendering  vectors  (bad order of rendering surfaces and vec‐
324       tors). If you encounter such problems, try to  change  a  depth  buffer
325       number  in wxGUI Settings > Preferences > Map Display  > Advanced (pos‐
326       sible numbers are 0, 16, 24, 32). It is currently not possible to auto‐
327       matically  determine  the  right  number which is working for your com‐
328       puter.
329

SEE ALSO

331        wxGUI
332       wxGUI components
333
334       See also wiki page (especially various video tutorials).
335       Command-line module m.nviz.image.
336

AUTHORS

338       The wxNviz GUI
339
340       Martin Landa, Google Summer of Code 2008 (mentor: Michael  Barton)  and
341       2010 (mentor: Helena Mitasova)
342       Anna Kratochvilova, Google Summer of Code 2011 (mentor: Martin Landa)
343
344       The OGSF library and NVIZ engine
345
346       NVIZ  (GRASS’s  n-dimensional  visualization suite) was written by Bill
347       Brown, Terry Baker, Mark Astley, and David Gerdes, U.S. Army  Corps  of
348       Engineers Research Laboratories, Champaign, Illinois and UI GMS Labora‐
349       tory, Urbana, IL in the early 1990s.
350
351       Original documentation was written by Terry Baker  (spring  1995),  and
352       updated by Mark Astley, based on a document written by Bill Brown.  Ad‐
353       ditional design help and funding in the early 1990s by Helena  Mitasova
354       (CERL).  Tcl/Tk  support  added by Terry Baker. Ported to Linux by Jaro
355       Hofierka and others. Conversion from SGI IRIS  GL  code  to  OpenGL  by
356       Justin  Hickey. Further program and documentation (2004) updates by Bob
357       Covill, Tekmap Consulting. 3D volume support by Tomas Paudits with  su‐
358       pervision  from  Jaro  Hofierka and Helena Mitasova.  Fly-through mode,
359       thematic site attributes, and picking by Massimo Cuomo (ACS)  with  up‐
360       dates  by Michael Barton. GRASS 6 vector support by Radim Blazek. Addi‐
361       tional updates by Markus Neteler, Martin  Landa,  Glynn  Clements,  and
362       Hamish Bowman.
363
364       NVIZ  evolved  from  the earlier GRASS program SG3d written for Silicon
365       Graphics IRIS GL by Bill Brown and Dave Gerdes at USA  CERL,  1990-1995
366       and  from  the  NVIZ Motif version written by Bill Brown with contribu‐
367       tions by Terrance McGhee.
368

SOURCE CODE

370       Available at: wxGUI 3D View Mode source code (history)
371
372       Accessed: Fri Jun  3 13:27:06 2022
373
374       Main index | Wxgui index | Topics index | Keywords  index  |  Graphical
375       index | Full index
376
377       © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
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381GRASS 8.2.0                                                      wxGUI.nviz(1)
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