This video* (linked at the correct time of 0:26 sec) shows a scene inside a room of a home. Apparently projected on the wall is an imperfect but recognizable image of the outside street scene. The light forming this image has passed through a translucent curtain.

Here's a still which shows the projected image of an outside building onto the wall:

An opaque fabric material would just cast a shadow. I would have expected a translucent material to totally distort any pattern on the incoming light from the other side. And without any curtain you would of course expect also get no discernable image.

Instead it seems like this fabric is actually behaving like a lens? I am familiar with the concept of a camera-obscura, which is basically just a tiny hole that acts like a lens. Extrapolating from that... maybe the fabric is like thousands of such pinholes. But what is the mechanism that allows them to form a more-or-less focused image?

Note that the projected image covers a large wall area, including a portion of one wall which is perpendicular to the curtain; so the "focal plane distance" (if that's the right analogy) is not consistent.

It doesn't appear that this video is a fake, though I guess I can't rule that out.

_{(*) Its not a very serious video in total, and could even be NSFW, perhaps}

This video* (linked at the correct time of 0:26 sec) shows a scene inside a room of a home. Apparently projected on the wall is an imperfect but recognizable image of the outside street scene. The light forming this image has passed through a translucent curtain.

Here's a still which shows the projected image of an outside building onto the wall:

And another with someone's arm adding a shadow:

An opaque fabric material would just cast a shadow. I would have expected a translucent material to totally distort any pattern on the incoming light from the other side. And without any curtain you would of course expect also get no discernable image.

Instead it seems like this fabric is actually behaving like a lens? I am familiar with the concept of a camera-obscura, which is basically just a tiny hole that acts like a lens. Extrapolating from that... maybe the fabric is like thousands of such pinholes. But what is the mechanism that allows them to form a more-or-less focused image?

Note that the projected image covers a large wall area, including a portion of one wall which is perpendicular to the curtain; so the "focal plane distance" (if that's the right analogy) is not consistent.

It doesn't appear that this video is a fake, though I guess I can't rule that out.

_{(*) Its not a very serious video in total, and could even be NSFW, perhaps}