Invert Camera standard Axes


I really tried hard to solve following problem but I do not come to an end…

I have succedded now to export complete scene graph from Blender to Collada and to import it from Collade to JME. The only thing that missing is correct camera rotation.

In blender, a camera looks, per default into (0,0,-1) direction, i.e. into negative z direction. This means, that if camera has (0,0,0) rotation, it looks into (0,0,-1). The rotation from COLLADA to JME is done correctly. I know this, because I checked it out with object rotation of different objects. In JME it seems as if the camera looks per default into (0,0,1) direction. I know that there are up, left and direction properties. As far as I understand those three vectors do not build up mirror matrices but reflect the rotation properties in form of vectors. If I rotate my camera in JME, the up, left and direction vectors change (generally all, in special cases of course only some of them). Setting the scaleZ value from 1 to -1 seems to make no difference. How can I map a camera with (0,0,-1) default direction to a camera to (0,0,1)?

I know that JME uses its own default settings and this is ok. I like JME very much. But for those who are already experienced in 3D programming I would have another question. If all programs use their own standard direction values for camera and only the node rotation is exported to collada, how can a program determine the correct transformation?

Thanks a lot.