Math about the 2 point perspective

Developers Ruby API
1

Hi all,

Here is my problem: I have an aerial images, and I have calculated the position and orientation of the camera and can successfully load the image as background to matchphoto by the Ruby API.

For a 3D projection, the basic math for a point P(X, Y, Z, 1) projected to a image point m(x,y,1) is

m = K(R,t)P

and I can turn this formula to the (eye target up aspect_ratio focal length and fov) that are need to create a camera used by the matchphoto.

However, what confused me is the center_2d and scale_2d parameter of the camera when I pan and zoom the matchphoto scene.

My question is what is the mathematical significances of the two parameters for the 2 point perspective camera for the matchphoto? How can they tell how much I have panned or zoomed of the scene?

Thanks,

Han

2

I was searching lately why Enscape can not save properly 2PP in sKetchup and I found out that API doesn’t support Pan and Zoom in 2PP…

so as sKetchup can do it internally, there is no way to know or set proper values by any plugin or script…

3

It actually support reading Shift and Zoom
Sketchup.active_model.active_view.camera.scale_2d

Sketchup.active_model.active_view.camera.center_2d
but I didn’t see a setting methods…