VTK (visualization toolkit) versus OSG (OpenSceneGraph) , other?

Question

Does anyone have experience to fairly compare VTK and OpenSceneGraph? I'm more familiar with VTK, but I'm curious as to whether anyone has tried both extensively.

I have both built, 5.6 vtk and 2.9.9 osg, can run the examples... at first glance OSG seems more 'rough', but maybe that's OK. In particular I worry about being able to fiddle with low level openGL in VTK; e.g. I bet glReadPixels would behave more nicely with OSG. Comments?

(or is there a nice 'other' that I'm missing? I know others exist, but please take a look at the massive scope of OSG and VTK...)

Answer 1

VTK and OSG really solve different problems, so which you should use depends on what you are trying to accomplish! VTK is primarily intended for scientific visualization, and as such is more geared towards data visualization algorithms. It might have some ability to work in a scene graph mode, but mainly that is so that different datasets can be registered (overlaid) on top of each other. It's not really intended for representing arbitrary scenes (though it could be shoehorned into it). And you're right, it is not intended that you mix OpenGL calls with VTK. Again, it can be done, but it's not necessarily easy.

OSG on the other hand, is the spiritual successor to SGI's Performer, and is intended more for arbitrary graphical scenes. It is very dependent on the scene-graph metaphor, which I would encourage you to read about (wikipedia has a decent article). I don't have much experience with it (being more on the sci-vis side of things).

In short, if you want to view isosurfaces of volumetric data, flow field visualizations, or other visualizations derived from scientific data, go with VTK. If you are trying to implement a virtual world of some sort, go with OSG (or something similar). If you are trying to accomplish something else, let us know, and perhaps someone can recommend a more apt tool for your needs.