The term Tachyscope has been used in another context for a vastly different purpose and I will use it here to describe an unphysical device that lives in a GR simulation and makes pictures, perhaps movies by means of tachyons emitted by tracers that we can drop into black holes and other violent mysteries.
While photons cannot escape a black hole, tachyons can. While the computer GR simulation pictures that I have understood depend on the chosen but arbitrary coordinate systems, and are thus not comparable between simulations, tachyons travel in trajectories precisely predicted by GR, if their velocities are known. Their paths are unique figments of the theory and not the artifices that must necessarily accompany the simulation. The geodesics depend only on the manifold and not the coordinate system.
We make the arbitrary decision that a tachyon begins with infinite velocity in the rest frame of the emitting tracer, itself a test particle falling along a geodesic of perhaps floating in an accelerated relativistic fluid. The equations of special relativity determine the superluminal velocity in other frames and differential geometry, given the metric, determines geodesics for tachyons just as well as it does for photons and test particles.
The movie production may need to lag the simulations as tachyons sometimes travel backwards in time, especially when the tracers are receding from you.
According to special relativity a tachyscope sees signals from an approaching tracer later than from a tracer at rest, but sooner than photons from the tracer. Conversely tachyon from a receding tracer are seen before they are emitted.
Many details remain to be worked out.
Another plan for graphics is to drop a camera into the fray and extract the movies it makes thru divine intervention—the ‘endoscopic’ camera.
A variation of the tachyscope is for the camera to do raytracing emitting infinite velocity tachyons much like the early Stoic theory of vision. This is even less physical than the source tachyon velocity, however. It may be more computationally feasible.