Transformation is a combined Translation, and Rotation around Center point, and Scale around Center and with orientation given by ScaleOrientation. For precise order of these operations, see X3D Transform node.
Default values of these fields indicate no transformation. So everything is zero, except Scale which is (1,1,1). Scale must always have all components > 0 (some operations depend that scale here is invertible and doesn't flip sides). Non-uniform scale (e.g. when you scale along X coordinate 2 times, but you scale along Y coordinate 3 times) works... to some extent, that is collisions with spheres (including camera radius) are not perfect in this case. For perfect results, keep your scale uniform.