[vtkusers] vtkGlyph3D problem?

Eric E. Monson emonson at cs.duke.edu
Tue Apr 13 07:34:41 EDT 2010


Hey Bill,

That is one situation where using the vtkGlyphSource2D with SetGlyphTypeToVertex() as the Source to your current vtkGlyph3D might work out well. Each vertex is really only one point, which is good for memory and for rendering speed. 

There is also some code in the ParaView repository for doing Point Sprites, but it's not something that's in the straight VTK collection.

If the memory problem is stemming from not just the number of points, but the number of scalars/vectors/tensors which are getting copied to each point, too, then it might be worth copying only the needed attributes to the data which will be glyphed with so many points.

Just as a side note, ParaView (www.paraview.org), which is built on top of VTK, works well for me when I'm trying to figure out how to build up my visualization. It doesn't have everything that's in VTK, but a lot of the parts are there, and it's a little easier sometimes to just play with combinations of representations to see what's possible or what looks good.

Talk to you later,
-Eric


On Apr 13, 2010, at 4:50 AM, Bill Chivas wrote:

> Hi Jerome,
> 
> good argument!
> I use glyph mechanism in order to represent the points on the grid. Can you think of other way to do that?
> Again, it seems to me impossible that there is no way with vtk to visualize the points and the grid at the same time!
> 
> Bill
> 
> 2010/4/13 Jérôme <jerome.velut at gmail.com>
> Hi,
> The "not able to allocate..." message is the usual one when you don't have enough memory.
> Don't forget that your sphere will be copied at each input point. Thus the final number of 
> points will be:
>    number_of_sphere_points * number_of_input_points
> 
> eg. 20x20 spheres = 400 points * 75k = 30M
> 
> each input point data is copied over each sphere point. It multiplies the amount of needed 
> memory as well (fo instance, a tensor multiplies by 9, if it's double data it is 4 octets 
> more, etc.)
> 
> HTH 
> Jerome
> 
> 
> 2010/4/13 Sebastian Gatzka <sebastian.gatzka at stud.tu-darmstadt.de>
> I'm experiencing the same problem!
> 
> Any ideas? Lack of memory?
> 
> Am 13.04.2010 10:27, schrieb Bill Chivas:
>> 
>> Hi all,
>> 
>> i use vtkGlyph3D with source a vtkSphereSource and input a vtkunstructuredgrid.
>> Grids with small number of vertices (approximately <10K ) are glyphed ok.
>> But large grids (e.g. vertices==75K) are not glyphed! A vtk message appears saying "not able to allocate...something" (i can't read the whole).
>> 
>> What is the problem? Large grids with many vertices can't be glyphed?
>> 
>> Bill
>> 
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