Object Localization using Dynamic Template Warping

Abstract

A simple method is presented for detecting, localizing and recognizing classes of objects, while accommodating a wide variation in an object's pose. The method utilizes a small two-dimensional template that is warped into an image, and converts localization to a one-dimensional sub-problem, with the search for a match between image and template executed by dynamic programming. The method recovers three of the six degrees of freedom of motion (2 translation, 1 rotation), accommodates two more degrees of freedom in the search process (1 rotation, 1 translation), and is extensible to the final degree of freedom. Experiments demonstrate that the method provides an efficient search strategy that outperforms normalized correlation. This is demonstrated in the example domain of face detection and localization, and is extended to more general detection tasks. An additional technique recovers a rough object pose from the match results, and is used in a two stage recognition experiment in conjunction with maximization of mutual information.

Some Results

Detection:

The color code used indicates the mapping between template columns and image columns returned by the system. This mapping can then be used to solve for a partial pose.

Partial Pose Solution:

This is the rendering of the partial pose returned by the pose-solver.

Click here for a movie of the partial pose solution.

Final Pose Solution using Mutual Information:

This figure shows the initial pose given to the MI pose solver after the partial pose solution. The final pose is illustrated by a rendering of the 3D model, and by an overlay of points subsampled from the object surface in the next row. From the figure, we see that the final solution given by the MI alignment has corrected the x-rotation error, and the pose in the final rendered image agrees with the input pose.