1wxGUI.nviz(1) GRASS GIS User's Manual wxGUI.nviz(1)
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7 display, GUI, visualization, graphics, raster, vector, raster3d
8
10 Note: wxNviz is currently under development. Not all planned function‐
11 ality is already implemented.
12 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 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 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 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.
36
38 Â Generate command for m.nviz.image
39 Generate command for m.nviz.image based on current state.
40 Â 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 Â Show help
46 Show this help.
47
49 The 3D view toolbox is integrated in the Layer Manager. The toolbox has
50 several tabs:
51 · View for view controlling,
53 · Data for data properties,
55 · Appearance for appearance settings (lighting, fringes, ...).
57 · Analysis for various data analyses (only cutting planes so
59 far).
60 · Animation for creating simple animations.
62 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
67 (azimuth). You click and drag the puck to change the current eye posi‐
68 tion. Another way to change eye position is to press the buttons around
69 the position box representing cardinal and ordinal directions.
70 There are four other buttons for view control in the bottom of this
72 panel (following label Look:):
73 · here requires you to click on Map Display Window to determine
75 the point to look at.
76 · center changes the point you are looking at to the center.
78 · top moves the current eye position above the map center.
80 · reset 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 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 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 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
101 direction is controlled by mouse cursor position on screen. Flight
102 speed can be increased/decreased stepwise by keys PageUp/PageDown,
103 Home/End or Up/Down arrows. Speed is increased multiple times while
104 Shift key is held down. Holding down Ctrl key switches flight mode in
105 the way that position of viewpoint is changed (not the direction).
106 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 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 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 To set given draw settings for all loaded surfaces press button "Set to
137 all".
138 The bottom half of the panel has options to set, unset or modify
140 attributes of the current surface. Separate raster data or constants
141 can be used for various attributes of the surface:
142 · color - 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 · mask - raster map that controls the areas displayed from the
148 current surface.
149 · transparency - 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).
153 · shininess - raster map or constant value that controls the
155 shininess (reflectivity) of the current surface. Range from 0
156 to 100.
157 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 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 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 You can define the width (in pixels) of the line features, the color
176 used for lines or point markers.
177 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 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 For 2D/3D vector points you can also set the size of the markers. Cur‐
189 rently are implemented these markers:
190 · x sets the current points markers to a 2D "X",
192 · sphere - solid 3D sphere,
194 · diamond - solid 3D diamond,
196 · cube - solid 3D cube,
198 · box - hollow 3D cube,
200 · gyroscope - hollow 3D sphere,
202 · asterisk - 3D line-star.
204 Thematic mapping can be used to determine marker color and size (and
206 line color and width).
207 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 · isosurface - the levels of values for drawing the 3D raster(s)
218 as isosurfaces,
219 · and slice - drawing the 3D raster as cross-sections.
221 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
225 options 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 · isosurface value - reference isosurface value (height in map
230 units).
231 · color - raster map or constant color to drape over the current
233 3D raster.
234 · mask - raster map that controls the areas displayed from the
236 current 3D raster.
237 · transparency - 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 · shininess - 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
248 attributes.
249 3D rasters can be moved the same way like surfaces do.
251 Analysis
253 Analysis tab contains Cutting planes panel.
254 Cutting planes
256 Cutting planes allow cutting surfaces along a plane. You can switch
257 between six planes; to disable cutting planes switch to None. Ini‐
258 tially the plane is vertical, you can change it to horizontal by set‐
259 ting tilt 90 degrees. The X and Y values specify the rotation center of
260 plane. You can see better what X and Y do when changing rotation. The
261 Height parameter applies only when changing tilt concurrently. Press
262 the Reset button to reset the current cutting plane.
263 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 Appearance
269 Appearance tab consists of three collapsible panels:
270 · Lighting for adjusting light source
272 · Fringe for drawing fringes
274 · Decorations to display north arrow and scale bar
276 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 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 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 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
295 directory 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
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
303 parameters, or to set the background color of the Map Display Window
304 (the default color is white).
305
307 · Labels, decoration, etc. (Implemented, but not fully func‐
308 tional)
309 · Surface - mask by zero/elevation, more interactive positioning
311 · Vector points - implement display mode flat/surface for 2D
313 points
314 · ...
316
318 wxNviz is under active development and distributed as "Experimental
319 Prototype".
320 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
331 wxGUI
332 wxGUI components
333 See also wiki page (especially various video tutorials).
335 Command-line module m.nviz.image.
336
338 The wxNviz GUI
339 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 The OGSF library and NVIZ engine
345 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 Original documentation was written by Terry Baker (spring 1995), and
352 updated by Mark Astley, based on a document written by Bill Brown.
353 Additional design help and funding in the early 1990s by Helena
354 Mitasova (CERL). Tcl/Tk support added by Terry Baker. Ported to Linux
355 by Jaro Hofierka and others. Conversion from SGI IRIS GL code to OpenGL
356 by Justin Hickey. Further program and documentation (2004) updates by
357 Bob Covill, Tekmap Consulting. 3D volume support by Tomas Paudits with
358 supervision from Jaro Hofierka and Helena Mitasova. Fly-through mode,
359 thematic site attributes, and picking by Massimo Cuomo (ACS) with
360 updates by Michael Barton. GRASS 6 vector support by Radim Blazek.
361 Additional updates by Markus Neteler, Martin Landa, Glynn Clements, and
362 Hamish Bowman.
363 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
370 Available at: wxGUI 3D View Mode source code (history)
371 Main index | Wxgui index | Topics index | Keywords index | Graphical
373 index | Full index
374 © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
376GRASS 7.8.5 wxGUI.nviz(1)