[Frances]

Hi Togusa,

Perhaps it is a caustic reflection from the metal chair leg? Does it show up if the chair frame is non-reflective?

[Thomas An.]

Hi Togusa88,

As Frances mentioned what you see is not a shinny floor but the caustic from the metallic leg.

It is like taking a handheld mirror and directing a flashlight beam to that mirror, then you will see the beam of light reflected on the wall of your room.

In the same way the leg of the chair acts like a mirror and reflects light against the diffuse floor.

[Thomas An.]

Maxwell may have a couple of bugs here and there (particularly with some dielectric situations) but it does not make gross errors in terms of realism overall.

If that is how it is shown, then this would be the real life result; if you were to recreate the conditions.

In regards to the sharpness of the caustic, again, Maxwell behaves as in real life and the larger the emitter the more blurred the caustic becomes. Conversely, the smaller the emitter, the more focused the caustic will be.

(You can verify this by doing an physical experiment. Take a ring and put it close to an incandescent source and watch the caustic. Now take the same ring and place it near a fluorescent source (long tube)... observe that the caustic is more blured in comparison...