i think my problem is simply my no-knowledge of orthogonal perspective rendering...
i was wondering if i have to init the matrix4 with 640units height and 480units width at a resolution of 640x480 to place the nodes at positions of 2dImages.
for example:
is this position:
draw2dImage at 100x100 at resolution 640x480
...the same as:
particlesystemscenenode with orthomatrix 640,480,-10,10
->setPosition(-220,-140,0)
maybe i misunderstand the orthogonal thing at all, so never mind ^^