[GRASS-dev] Replacement of NVIZ

Sören Gebbert soerengebbert at gmx.de
Mon Apr 23 07:06:30 EDT 2007

Dear Michael,

Michael Barton schrieb:
> It's great that we can export GRASS data to be used in high-end
> multi-dimensional visualization platforms like Paraview and MayVi2. I've
> used Paraview a bit. I wouldn't call it easy or intuitive, but it is quite
> sophisticated and powerful--though not particularly fast in my experience.
> However, using any of these packages is not a replacement for NVIZ. NVIZ
> will let a user quickly and seamlessly render 2, 2.5, 3, and 4 dimensional
> data within a GRASS GIS session. This is a real bonus. And NVIZ does this
> better than any other rendering engine within a GIS that I've seen. In this
> sense, NVIZ has a different goal from Paraview and other dedicated
> multidemensional rendering packages.
> So I hope that we can get NVIZ ported to wxPython and make it an even more
> seamless part of the geospatial visualization tools for GRASS. Making

Good news. Nice to hear that. I hope you will redesign the gui, so it will be more intuitive.
I have had a look at the NVIZ code and was afraid that this construct is not maintainable.
Well, this is hopefully related to my very little knowledge of software design and C coding
with Tcl/Tk bindings.

> tighter connections between GRASS and other, external visualization tools is
> also a worthy plan--similar to the integration between GRASS and R. But
> IMHO, we should not abandon NVIZ or something like it.

I guess you are right. An integrated 2.5d, 3d and 4d visualization tool is important.
The good thing is that ParaView is not only a visualization tool, it is
a preprocessing and analysis tool with 4d support and powerful threaded image processing.

Best regards

> Michael
> On 4/22/07 4:31 PM, "Sören Gebbert" <soerengebbert at gmx.de> wrote:
>> Syd,
>> Syd Visser schrieb:
>>> Soren
>>> Paraview3 uses Qt and MayaVi2 uses Wxpython thus we are leaning more
>>> towards MayaVi2  although we use Paraview2.6 extensively but strictly as
>>> a viewer.
>>> We find MayaVi2 is also more open to user development thus easier to
>>> extend.
>> I'm developing with VTK and Qt since several years and have used ParaView1-2
>> for several years.
>> My experience with MayaVi is little, because the user interface was too
>> horrible.
>> IMHO ParaView3 is the better choice. It has a sophisticated but very
>> intuitive user interface and is developed by well known institutes and
>> kitware.
>> And they are doing a great job. ParaView is designed to visualize huge
>> datasets in parallel.
>> MayaVi2 depends on Traits, TVTK, Envisage and wxPython. A lot of new
>> dependencies (except wxPython).
>> And for now i'm not able to get even the new grass wxPython gui to run on my
>> debian etch system
>> because of the dependencies.
>> ParaView3 depends only on Qt4.2. Qt is available for many, many platforms as
>> well as VTK.
>> (i still don't understand why wxWidgets and python was choosen for the new
>> grass gui and not Qt
>> and python ...)
>> The only thing we need to provide is a data server and gui plugin for
>> ParaView3:
>> http://www.paraview.org/Wiki/Plugin_HowTo
>> And when ParaView3 reaches a stable state and i have some spare time i'm
>> absolutely willingly to implement them!
>> IMHO the data server and the reader/writer to the grass database
>> (grass data should be modified with Paraview3 and stored back into the grass
>> database :) if possible)
>> should be implemented in C++ for performance reasons. I would not use the
>> grass python wrapper
>> to get the data into a visualization system. The grass raster, voxel and
>> vector functions can be
>> accessed from C++ code directly.
>> The data server should provide access to the grass database to read and write
>> raster, volume and vector data.
>> And ParaView3 should be extended with a nice little Qt gui to access the grass
>> data directly from the toolbar
>> (like Qgis). We don't need to touch the ParaView3 sources, we only need to
>> implement plugins.
>> A screenshot of ParaView3 handling grass raster, volume and vector data
>> (exported with the *.out.vtk modules)
>> is available here:
>> http://www-pool.math.tu-berlin.de/~soeren/grass/modules/screenshots/ParaView3_
>> Screenshot_grass_data.png
>> Just my two cents ...
>> sorry for my English
>> Best regards
>> Soeren
>>> Thanks
>>> Syd
>>> Sören Gebbert wrote:
>>>> Hi,
>>>> Syd Visser schrieb:
>>>>> We use enthought open source tool suite http://www.enthought.com/
>>>>> which contains Numpy, SciPi and numerous other packages.
>>>>> our main use is with Matplotlib and Chaco for 2D graphs and MayaVi2
>>>>> for 3D graphics
>>>>> I think these packages would be well worth having a close look at
>>>>> especially MayaVi2 (Python wrapped VTK) for the 3D graphics.
>>>> I would like to prefer a C++ grass data server + grass gui plugin for
>>>> paraview3
>>>> to visualize 3d data. This would a nice and fast solution.
>>>> Best regards
>>>> Soeren
>>>>> thanks
>>>>> Syd
> __________________________________________
> Michael Barton, Professor of Anthropology
> School of Human Evolution & Social Change
> Center for Social Dynamics & Complexity
> Arizona State University
> phone: 480-965-6213
> fax: 480-965-7671
> www: http://www.public.asu.edu/~cmbarton

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