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// Copyright (c) 2007, 2008, 2009, 2011 libmv authors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
#include "libmv/tracking/pyramid_region_tracker.h"
#include <vector>
#include "libmv/image/convolve.h"
#include "libmv/image/image.h"
#include "libmv/image/sample.h"
#include "libmv/logging/logging.h"
namespace libmv {
static void MakePyramid(const FloatImage &image, int num_levels,
std::vector<FloatImage> *pyramid) {
pyramid->resize(num_levels);
(*pyramid)[0] = image;
for (int i = 1; i < num_levels; ++i) {
DownsampleChannelsBy2((*pyramid)[i - 1], &(*pyramid)[i]);
}
}
bool PyramidRegionTracker::Track(const FloatImage &image1,
const FloatImage &image2,
double x1, double y1,
double *x2, double *y2) const {
// Shrink the guessed x and y location to match the coarsest level + 1 (which
// when gets corrected in the loop).
*x2 /= pow(2., num_levels_);
*y2 /= pow(2., num_levels_);
// Create all the levels of the pyramid, since tracking has to happen from
// the coarsest to finest levels, which means holding on to all levels of the
// pyraid at once.
std::vector<FloatImage> pyramid1(num_levels_);
std::vector<FloatImage> pyramid2(num_levels_);
MakePyramid(image1, num_levels_, &pyramid1);
MakePyramid(image2, num_levels_, &pyramid2);
for (int i = num_levels_ - 1; i >= 0; --i) {
// Position in the first image at pyramid level i.
double xx = x1 / pow(2., i);
double yy = y1 / pow(2., i);
// Guess the new tracked position is where the last level tracked to.
*x2 *= 2;
*y2 *= 2;
// Save the previous best guess for this level, since tracking within this
// level might fail.
double x2_new = *x2;
double y2_new = *y2;
// Track the point on this level with the base tracker.
LG << "Tracking on level " << i;
bool succeeded = tracker_->Track(pyramid1[i], pyramid2[i], xx, yy,
&x2_new, &y2_new);
if (!succeeded) {
if (i == 0) {
// Only fail on the highest-resolution level, because a failure on a
// coarse level does not mean failure at a lower level (consider
// out-of-bounds conditions).
LG << "Finest level of pyramid tracking failed; failing.";
return false;
}
LG << "Failed to track at level " << i << "; restoring guess.";
} else {
// Only save the update if the track for this level succeeded. This is a
// bit of a hack; the jury remains out on whether this is better than
// re-using the previous failed-attempt.
*x2 = x2_new;
*y2 = y2_new;
}
}
return true;
}
} // namespace libmv
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