[GRASS-dev] [GRASS GIS] #1992: wxNviz: confusing to add raster3d isosurfaces

[GRASS GIS]

#1992: wxNviz: confusing to add raster3d isosurfaces
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 Reporter:  hamish       |       Owner:  grass-dev@…              
     Type:  enhancement  |      Status:  new                      
 Priority:  normal       |   Milestone:  6.4.3                    
Component:  wxGUI        |     Version:  svn-releasebranch64      
 Keywords:  wxnviz       |    Platform:  Linux                    
      Cpu:  x86-64       |  
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 Hi,

 I'm testing volumes in wxNviz, using the vox50 example from the wiki:
  http://grasswiki.osgeo.org/wiki/3D#Examples

 It's working, but I find the adding-isosurfaces part a bit counter
 intuitive, and the 3D view was completely blank until I figured out to
 manually change the viewing height. For the isosurface the main confusion
 was because it works the opposite way to the [Submit] button when editing
 vector attributes- there you edit first then hit the "go" button. With the
 isosurfaces you press the [Add] button first, it creates a new isolevel
 using the minimum data value, then you change the value from that default
 by hand and just sort of press enter or change the field somehow and it
 applies the change silently.
 (maybe a "go" button to the right of the Isosurface level: text entry box
 would help even if it did very little besides be yet another way to apply
 the change? sort of like close-door buttons on elevators which don't do
 much but are satisfying to press anyway)

 Until I figured out I was looking at it all backwards it was all rather
 confusing.. at first I typed in a value "1000.0" then pressed [Add], and
 my 1000 was replaced by a 2.5 (the min value) in both the text entry box
 and the level list. I kept on overwriting the previously entered value
 adding new "2.5" value levels to the end of the list. Obvious in hind-
 sight, but it's quite easy to get lost in it when just starting out.

  -- Perhaps the fix for this confusion is to simply grey-out the
 "Isosurface value:" entry box until at least one isosurface has been added
 with the [Add] button? Then you get the order of buttons to press in your
 mind from the beginning.


 Also just to mention a bit of a bug to look out for: after adding
 isolevels out of order and moving them up and down in the list, 2 of 4 iso
 surfaces never rendered. Adding new isosurfaces at nearby (+/-) levels
 rendered ok. No error messages. It's a little hard to reproduce, I'll post
 back in a new ticket if I can figure out how to trigger it every time.
 Perhaps the value is still sitting at 2.5 (default,minimum) instead of the
 2000, 3000 showing in the surface level list (??).


 Finally, for that data (spatial range is 0..50 in x,y,z) the default
 viewing height is 5000 if you have no other map layers open, so you see
 nothing in the display until you realize to manually type in 25 or 50 into
 the Height: slider control. For cases when 3D view mode starts with 3D
 rasters alone loaded, could it take a hint from the current region's
 top/bottom value, or perhaps the first raster3d's values for the same, as
 to what to set the starting min/max height around? (also, in this case the
 old Tcl/Tk NVIZ default value of perspective=40 starts it out in a better
 view than the new wxNviz default of =20)


 thanks,
 Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1992>
GRASS GIS <http://grass.osgeo.org>