[GRASS-dev] Native GRASS support in VTK + Python and Java

[Benjamin Ducke]

This is great! Did you consider writing a little plug-on for one
of the VTK viewers, like ParaView or VisIt, to allow direct access
to GRASS data from there?

Cheers,

Ben

Soeren Gebbert wrote:
> Hi,
> JFYI i have implemented a small demo library which connects parts of the 
> grass gis library
> with the Visual-Tool-Kit VTK.
> It is called vtkGRASSBridge.
> 
> Additionally the VTK Python and Java wrapping mechanism have been 
> enabled. So the user can use the
> library from C++, Python and Java.
> 
> Features:
> * The library can read and write raster maps row by row, as well as 
> regions and the raster history.
> * It can list files of the grass database.
> * It can convert grass raster maps into the vtkImageData format and the 
> other way round.
> Missing Features:
> * Full raster support (categories, colors, ..)
> * Imagery support (groups, ...)
> * Full vector support ....
> * ....
> 
> You can use every vtkDataSet processing algorithm available in VTK (more 
> than 50 i think)
> to process the converted raster map and write it back to the grass 
> raster database.
> 
> You can use the VTK render functionality to display the raster map.
> 
> There are examples and tests in the library showing this functionality 
> in Python.
> 
> The documentation of the library can be found here:
> http://www-pool.math.tu-berlin.de/~soeren/grass/files/vtkGRASSBridge/doc/html/index.html
> 
> The GPL source code is located here:
>  http://www-pool.math.tu-berlin.de/~soeren/grass/files/vtkGRASSBridge/vtkGRASSBridge_0.1.tar.gz
> 
> Here is a small Python code example to read and write grass raster maps 
> in Python (within a grass session):
> 
> ##############################################
> #include the VTK and vtkGRASSBridge Python libraries
> from libvtkCommonPython import *
> from libvtkFilteringPython import *
> from libvtkGraphicsPython import *
> from libvtkRenderingPython import *
> from libvtkIOPython import *
> from libvtkImagingPython import *
> from libvtkGRASSBridgeIOPython import *
> from libvtkGRASSBridgeCommonPython import *
> 
> #Initiate grass
> init = vtkGRASSInit()
> 
> #The region settings
> region = vtkGRASSRegion()
> region.ReadCurrentRegion()
> region.SetCols(10)
> region.SetRows(10)
> region.AdjustRegion()
> 
> #Create a new map and write some data into it
> writer = vtkGRASSRasterMapWriter()
> writer.SetMapTypeToCELL()
> writer.SetRegion(region)
> writer.UseUserDefinedRegion()
> writer.OpenMap("test_cell")
> 
> #this is the row buffer
> data = vtkIntArray()
> data.SetNumberOfTuples(writer.GetNumberOfCols())
> 
> #iterate over each raster cell
> for i in range(writer.GetNumberOfRows()):
>     for j in range(writer.GetNumberOfCols()):
>         data.SetTuple1(j, i + j + 100)
>     writer.PutNextRow(data)
> 
> #close the map
> writer.CloseMap()
> 
> #now reopen the map for reading
> reader = vtkGRASSRasterMapReader()
> reader.OpenMap("test_cell")
> 
> #print the cells to stdout
> print " "
> for i in range(reader.GetNumberOfRows()):
>     data = reader.GetRow(i)
>     for j in range(reader.GetNumberOfCols()):
>         print data.GetTuple1(j),
>     print " "
> 
> #print the range of the raster map
> val = [0,0]
> reader.GetRange(val);
> print "Range ", val
> 
> #print the history
> print reader.GetHistory()
> reader.CloseMap()
> 
> #############################################
> 
> 
> Have fun
> Soeren
> 
> 
> ------------------------------------------------------------------------
> 
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-- 
Benjamin Ducke
Senior Applications Support and Development Officer

Oxford Archaeological Unit Limited
Janus House
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OX2 0ES
Oxford, U.K.

Tel: +44 (0)1865 263 800 (switchboard)
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benjamin.ducke at oxfordarch.co.uk




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