RE: [ccmasterkernel U20] Photogroup functions pixelToRay/point3dToPixel

Lin Qun — Wed, 25 Oct 2023 15:53:11 GMT

Thank you so much for the formula “p3dcamera = rotation * (p3dworld – center)”
I haven't found the definition of Photo.pose.rotation and Photo.pose.center in sdk. I mistaken that as "p3dcamera = rotation * p3dworld + center" and always get the wrong projection. Your answer saved me a lot of trouble. Thank you so much!

RE: [ccmasterkernel U20] Photogroup functions pixelToRay/point3dToPixel

Oto — Tue, 24 Oct 2023 11:42:25 GMT

Description: Photogroup functions pixelToRay/point3dT
Product: ContextCapture
Product Area: Options

These functions are needed to project a 3D point onto a photo and get its 2D pixel coordinates (useful for reprojection error computation, texturing or many other applications) and to do the opposite transformation, get a 3D ray from 2D pixel coordinates.

In practice to project a 3D point onto an image given its 3D position in the world reference system, the photo pose in the world and the photogroup properties some have to:

Transform the 3D point from world to camera reference system by applying the photo pose
p3dcamera = rotation * (p3dworld – center)
Project this p3dcamera point to the image using the new SDK function “point3dToPixel”

To get a 3D ray from a pixel point some have to:

Get a 3D ray in camera coordinate system using the new SDK function “pixelToRay”
Transform the 3D ray from camera pose to world reference system
ray3dworld = rotationTransposed * ray3dcamera + center