Importing Camera CAHV format - up and direction vectors?
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I've written a quick importer for a fun little project that imports camera location data for a bunch of image frames. But I can't determine what in this data is what I would use for the up and direction vector for making a new camera. It supplies quite a few vectors, and I'm not sure which are the ones I want. To make matters worse, there is other 3d data that comes in with th file, and it is all mirrored what it should be, and the y and z for 3d points had to be swapped.
So between not entirely trusting the directions of the provided vectors, I can't even determine which ones would be for the sketchup z-vector and the vector for the direction the camera is facing.
I've got some better ideas for how to test it later, but I was hopinh maybe someone here was familiar with these camera terms.
This is the instructions that come with the camera data:
# Description of the CAHV camera model; # ------------- # (Cx, Cy, Cz) ; CameraPosition [mm] # (Ax, Ay, Az) ; RotationAxis2 [unit vector] # (Hx, Hy, Hz) ; RotationAxis0 [pel] (including FocalLength, PixelSizeX, and Principal Point offset) # (Vx, Vy, Vz) ; RotationAxis1 [pel] (including FocalLength, PixelSizeY, and Principal Point offset) # (K3, K5) ; Radialdistortion; K3 [1/(mm)^2] K5 [1/(mm)^4] # (sx, sy) ; PixelSize [mm/pel] # (Width, Height) ; ImageSize [pel] # ------------- # (ppx, ppy) ; Principal Point offset [pel] # f ; Focal Length [mm] # fov ; Horizontal Field of View [degree] = (2*atan(0.5*Width*sx/f)*180/PI; # (H0x, H0y, H0z) ; RotationAxis0 [unit vector] # (V0x, V0y, V0z) ; RotationAxis1 [unit vector] # ------------- # (x, y) ; image coordinates [pel] # (X, Y, Z) ; 3D coordinates [mm] # ------------- # Projection of 3D coordinates in the camera image; # [ x' ] = [ Hx Hy Hz ] [ 1 0 0 -Cx] [ X ] # [ y' ] = [ Vx Vy Vz ] [ 0 1 0 -Cy] [ Y ] # [ z' ] = [ Ax Ay Az ] [ 0 0 1 -Cz] [ Z ] # [ 1 ] # or # [ x' ] = [f/sx 0 ppx] [ H0x H0y H0z ] [ 1 0 0 -Cx] [ X ] # [ y' ] = [0 f/sy ppy] [ V0x V0y V0z ] [ 0 1 0 -Cy] [ Y ] # [ z' ] = [0 0 1 ] [ Ax Ay Az ] [ 0 0 1 -Cz] [ Z ] # [ 1 ] # then x = x'/z' and y = y'/z' , if the origin of the image coordinates is in the center of the image # or x = x'/z' + 0.5*(Width-1) and y = y'/z' + 0.5*(Height-1) , if the origin of the image coordinates is in the upper left cornerA big thanks to anyone who takes a stab at this or thinks they have an answer for which od the provided vectors correlate to what I need. Thanks!
Chris
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Chris,
Have a look at the film and stage plugin - if I remember, there is some code in it which might be useful.
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