Martin,

I’d check for any settings relating to lighting/illumination for the CAD workspace – adjusting number of lamps might make the interpretation of the scene less prone to ‘flipping’ between possible options.

I can see both options if I try, the ‘cube in the corner’ one is more obvious to me.

Just goes to show that representing a 3D object on a 2D screen does have limitations.

Yes i can see both does it have anything to do with wearing glasses?

Hypothesis:

Both interpretations are good, but ultimately the ‘cube in a corner’ wins … because the view has an implied ‘ground-plane’ whereas the angle-plate is, un-naturally, free-floating.

Changing the viewpoint will probably flip the interpretation.

MichaelG.

When I first looked at it it was a cube in a corner, looked away and it became a 3 sided angle plate. Read down through the the posts went back to look at it and it is now a cube in a corner and won’t change. tried changing my viewing angle and the room lighting, still a cube in a corner!

John

If I cover up all the left except far right corner that bit turns to angle plate. Then I can gradually reveal the rest but it only holds for a second.

I can see a cube in a corner, or an upside down three sided angle plate. Why is the angle plate upside down is my question!?

Just out of curiosity I loaded it into Picaso and kept rotating it. Every once in a while it would change from the cube to the angle plate then back at unpredictable intervals. I have also found that if I stare at the bottom right hand corner it will change to the angle, look away it’s back to the cube, then stare at the corner again and it’s back to the angle.

John

It was a cube in a corner until I saw the video where depending on the angle it can also be the angle plate. What doe sit look like if you use perspective rather than orthographic?

Clearly we are all admirers of M.C. Escher’s drawings!

I used to frequent a cafe whose floor was two or three steps up from the pavement, in a street on a gentle hill slope. So if you sat next to the window, you looked slightly down onto the corner of a brick-columned, tile-roofed portico fronting a shop diagonally opposite.

Certain lighting conditions, especially street-lamps on dark Winter evenings, created a peculiar optical illusion giving this portico a peculiar, very Esher-esque form.

Sadly the cafe has gone, as the building completely destroyed by a fire several months ago.

(It was The Gorge Cafe, and the porticoed shop is Goulds, for them as know Dorchester town centre.)

That “nothing in particular” might be a very useful shape for an angle-plate!