Interactive 3D ScanningWithout Tracking

Abstract

Using inexpensive and readily available materials-a calibrated pair of cameras and a laser line projector-a 3D laser range scanner which requires no tracking is implemented in this paper. We introduce a planarity constraint for reconstruction, based on the fact that all points observed on a laser line in an image are on the same plane of laser light in 3D. This plane of laser light linearly parametrizes the homography between a pair of images of the same laser line, and this homography can be recovered from point correspondences derived from epipolar geometry. Points visible from multiple views can be reconstructed via triangulation and projected onto this plane, while points visible in only one view can be recovered via ray-plane intersection. The use of the planarity constraint during reconstruction increases the system's accuracy, and using the planes for reconstruction increases the number of points recovered. Additionally, an interactive scanning environment is constructed, where incremental reconstruction is used to provide continuous visual feedback. Reconstructions with this method are shown to have higher accuracy than standard triangulation.

3D Slit Scanning with Planar Constraints★

“…For example, a wrinkled white sheet of cloth could be draped behind the object. The reconstructions in this paper do not use a reflective background for support, but the results in the previous work [LVT07] did.…”

“…The algorithm described in the next sections applies to either a catadioptric stereo rig or a pair of synchronized cameras as in [LVT07]. In the catadioptric case, the camera parameters describe the virtual camera positions and orientations.…”

“…A third approach is to triangulate the points and then project them to the closest point on the plane. This is the approach used in our prior work [LVT07]. It combines the stability of triangulation with the constraint of planarity.…”

“…All points must lie in the plane of laser light Π. In previous work [LVT07], this was accomplished by a two stage process. First a point was triangulated (as described above), then the point was projected orthogonally onto Π.…”

“…In a recent paper [LVT07], we introduced a planarity constraint for the reconstruction of 3D points in a laser slit scanner with two cameras. This paper extends the previous work with a new reconstruction algorithm that computes the optimal reconstruction of points constrained to the plane.…”