**Figure 1**

The appearance of images projected onto the observer plane depends on three angles by which observer coordinates are rotated about the simulation region. The first rotation by ϕ_{Orient} spins the projection onto the observer plane about the origin of the observer plane, the second rotation by θ_{Obs} in determines the angle of the observer direction relative to the polar axis, and the third rotation by ϕ_{Obs} corresponds to an observer flying around the polar axis in the azimuthal direction.

**Figure 2**

Images are sums of slices normal to the observer direction nObs projected onto the xObs-yObs plane. To change observer azimuth, the observer coordinates (blue) “fly” around the fixed simulation coordinates (red).