Structure and Motion Reconstruction of Short Mobile Mapping Image Sequences

This paper presents a strategy for the automatic orientation of short image sequences acquired by Mobile Mapping Vehicles when the navigation solution is not available or not accurate enough. Using Structure and Motion reconstruction techniques, conjugate points are extracted and matched along the sequence, removing mismatches by robust estimation of the fundamental matrix and of the trifocal tensor. The final point coordinates and the orientation parameters are computed with a bundle adjustment with constraints, fixing the relative orientation of synchronous pairs and the exterior orientation parameters of the images at the ends of the strip. Sequences of about 90 stereo pairs for up to about 300 m have been oriented in countryside road sections. RMS discrepancies with respect to the navigation solution turned out below 50 cm for projection centers and 2.4° for attitude. Instability of the bundle adjustment solution due to poor imaging geometry is effectively balanced by the relative orientation constraint.