Projection question

[glad marlin]

There is a box that is transparent and casts an image onto a screen due the light behind it. The image on the screen must always be CONSTANT.
The lights position can be moved further back or closer but size of the box must change to keep the projection of the box on the screen the same.

Is there any way to prove that Fd changes proportionally or does not change proportionally to changes in D?

[glad marlin]

This isn't homework, it's just me trying to understand perspective concepts for art. I'm pretty sure that Fd increases proportionally with D but idk how to prove it

any pointers would be welcome

[solid igloo]

Not completely sure what you're asking but side length D on that box would be proportional to the distance fd away from the light source

And the area of the box is proportional to fd^2

U can prove it using similar triangles

[glad marlin]

ahh I see what you mean! Thank you!

.close