I just managed to see the 3-d flower. Only, I needed a pensil to help to properly converge my eyes.
BTW it's possible to see the a 3-D image in the picture with rings both far-converged and close-converged. Only in the latter case, the image is not prominent , but bulged-in or stamped and it's less in size.
Do you know some other exercises? Thank you in advance.