Pixel Point to world coordinates in Perspective camera

[nitinrhr183]

I have a 640*480 canvas where a video is running from webcam also(both canvas and webcam merged to same aspectratio)...From the video i am getting some pixel point say(videox,videoy)=(360,280). How can i place a 3d object to that pixel point . 3d object needs to be projected using world coordinates like (screenx,screeny,screenz)....So how to map from 2d (videox,videoy) to 3d (screenx,screeny,screenz) in perspective camera so that my object is rightly located

[jniac]

"pixel point" (2D) cannot be converted to "world point".

What you can get from a 2D point (eg screen position) in 3D space is a ray.
Then eventually, from that ray you can make a raycast into the scene in hope of finding some mesh.

Here a scene with raycast, and an object that go somewhere on a ray:

<ThingThatFollowAScreenPoint screenPoint={mouse} />

https://dzc4z.csb.app/