CDifodo.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#include "vision-precomp.h"  // Precompiled headers

#include <mrpt/vision/CDifodo.h>
#include <mrpt/utils/utils_defs.h>
#include <mrpt/utils/CTicTac.h>
#include <mrpt/utils/round.h>

using namespace mrpt;
using namespace mrpt::vision;
using namespace mrpt::math;
using namespace std;
using namespace Eigen;
using mrpt::utils::round;
using mrpt::math::square;

CDifodo::CDifodo()
{
        rows = 60;
        cols = 80;
        fovh = M_PIf * 58.6f / 180.0f;
        fovv = M_PIf * 45.6f / 180.0f;
        cam_mode = 1;  // (1 - 640 x 480, 2 - 320 x 240, 4 - 160 x 120)
        downsample = 1;
        ctf_levels = 1;
        width = 640 / (cam_mode * downsample);
        height = 480 / (cam_mode * downsample);
        fast_pyramid = true;

        // Resize pyramid
        const unsigned int pyr_levels =
                round(log(float(width / cols)) / log(2.f)) + ctf_levels;
        depth.resize(pyr_levels);
        depth_old.resize(pyr_levels);
        depth_inter.resize(pyr_levels);
        depth_warped.resize(pyr_levels);
        xx.resize(pyr_levels);
        xx_inter.resize(pyr_levels);
        xx_old.resize(pyr_levels);
        xx_warped.resize(pyr_levels);
        yy.resize(pyr_levels);
        yy_inter.resize(pyr_levels);
        yy_old.resize(pyr_levels);
        yy_warped.resize(pyr_levels);
        transformations.resize(pyr_levels);

        for (unsigned int i = 0; i < pyr_levels; i++)
        {
                unsigned int s = pow(2.f, int(i));
                cols_i = width / s;
                rows_i = height / s;
                depth[i].resize(rows_i, cols_i);
                depth_inter[i].resize(rows_i, cols_i);
                depth_old[i].resize(rows_i, cols_i);
                depth[i].assign(0.0f);
                depth_old[i].assign(0.0f);
                xx[i].resize(rows_i, cols_i);
                xx_inter[i].resize(rows_i, cols_i);
                xx_old[i].resize(rows_i, cols_i);
                xx[i].assign(0.0f);
                xx_old[i].assign(0.0f);
                yy[i].resize(rows_i, cols_i);
                yy_inter[i].resize(rows_i, cols_i);
                yy_old[i].resize(rows_i, cols_i);
                yy[i].assign(0.0f);
                yy_old[i].assign(0.0f);
                transformations[i].resize(4, 4);

                if (cols_i <= cols)
                {
                        depth_warped[i].resize(rows_i, cols_i);
                        xx_warped[i].resize(rows_i, cols_i);
                        yy_warped[i].resize(rows_i, cols_i);
                }
        }

        depth_wf.setSize(height, width);

        fps = 30.f;  // In Hz

        previous_speed_const_weight = 0.05f;
        previous_speed_eig_weight = 0.5f;
        kai_loc_old.assign(0.f);
        num_valid_points = 0;

        // Compute gaussian mask
        VectorXf v_mask(4);
        v_mask(0) = 1.f;
        v_mask(1) = 2.f;
        v_mask(2) = 2.f;
        v_mask(3) = 1.f;
        for (unsigned int i = 0; i < 4; i++)
                for (unsigned int j = 0; j < 4; j++)
                        f_mask(i, j) = v_mask(i) * v_mask(j) / 36.f;

        // Compute gaussian mask
        float v_mask2[5] = {1, 4, 6, 4, 1};
        for (unsigned int i = 0; i < 5; i++)
                for (unsigned int j = 0; j < 5; j++)
                        g_mask[i][j] = v_mask2[i] * v_mask2[j] / 256.f;
}

void CDifodo::buildCoordinatesPyramid()
{
        const float max_depth_dif = 0.1f;

        // Push coordinates back
        depth_old.swap(depth);
        xx_old.swap(xx);
        yy_old.swap(yy);

        // The number of levels of the pyramid does not match the number of levels
        // used
        // in the odometry computation (because we might want to finish with lower
        // resolutions)

        unsigned int pyr_levels =
                round(log(float(width / cols)) / log(2.f)) + ctf_levels;

        // Generate levels
        for (unsigned int i = 0; i < pyr_levels; i++)
        {
                unsigned int s = pow(2.f, int(i));
                cols_i = width / s;
                rows_i = height / s;
                const int rows_i2 = 2 * rows_i;
                const int cols_i2 = 2 * cols_i;
                const int i_1 = i - 1;

                if (i == 0) depth[i].swap(depth_wf);

                //                              Downsampling
                //-----------------------------------------------------------------------------
                else
                {
                        for (unsigned int u = 0; u < cols_i; u++)
                                for (unsigned int v = 0; v < rows_i; v++)
                                {
                                        const int u2 = 2 * u;
                                        const int v2 = 2 * v;
                                        const float dcenter = depth[i_1](v2, u2);

                                        // Inner pixels
                                        if ((v > 0) && (v < rows_i - 1) && (u > 0) &&
                                                (u < cols_i - 1))
                                        {
                                                if (dcenter > 0.f)
                                                {
                                                        float sum = 0.f;
                                                        float weight = 0.f;

                                                        for (int l = -2; l < 3; l++)
                                                                for (int k = -2; k < 3; k++)
                                                                {
                                                                        const float abs_dif = abs(
                                                                                depth[i_1](v2 + k, u2 + l) - dcenter);
                                                                        if (abs_dif < max_depth_dif)
                                                                        {
                                                                                const float aux_w =
                                                                                        g_mask[2 + k][2 + l] *
                                                                                        (max_depth_dif - abs_dif);
                                                                                weight += aux_w;
                                                                                sum +=
                                                                                        aux_w * depth[i_1](v2 + k, u2 + l);
                                                                        }
                                                                }
                                                        depth[i](v, u) = sum / weight;
                                                }
                                                else
                                                {
                                                        float min_depth = 10.f;
                                                        for (int l = -2; l < 3; l++)
                                                                for (int k = -2; k < 3; k++)
                                                                {
                                                                        const float d = depth[i_1](v2 + k, u2 + l);
                                                                        if ((d > 0.f) && (d < min_depth))
                                                                                min_depth = d;
                                                                }

                                                        if (min_depth < 10.f)
                                                                depth[i](v, u) = min_depth;
                                                        else
                                                                depth[i](v, u) = 0.f;
                                                }
                                        }

                                        // Boundary
                                        else
                                        {
                                                if (dcenter > 0.f)
                                                {
                                                        float sum = 0.f;
                                                        float weight = 0.f;

                                                        for (int l = -2; l < 3; l++)
                                                                for (int k = -2; k < 3; k++)
                                                                {
                                                                        const int indv = v2 + k, indu = u2 + l;
                                                                        if ((indv >= 0) && (indv < rows_i2) &&
                                                                                (indu >= 0) && (indu < cols_i2))
                                                                        {
                                                                                const float abs_dif = abs(
                                                                                        depth[i_1](indv, indu) - dcenter);
                                                                                if (abs_dif < max_depth_dif)
                                                                                {
                                                                                        const float aux_w =
                                                                                                g_mask[2 + k][2 + l] *
                                                                                                (max_depth_dif - abs_dif);
                                                                                        weight += aux_w;
                                                                                        sum +=
                                                                                                aux_w * depth[i_1](indv, indu);
                                                                                }
                                                                        }
                                                                }
                                                        depth[i](v, u) = sum / weight;
                                                }
                                                else
                                                {
                                                        float min_depth = 10.f;
                                                        for (int l = -2; l < 3; l++)
                                                                for (int k = -2; k < 3; k++)
                                                                {
                                                                        const int indv = v2 + k, indu = u2 + l;
                                                                        if ((indv >= 0) && (indv < rows_i2) &&
                                                                                (indu >= 0) && (indu < cols_i2))
                                                                        {
                                                                                const float d = depth[i_1](indv, indu);
                                                                                if ((d > 0.f) && (d < min_depth))
                                                                                        min_depth = d;
                                                                        }
                                                                }

                                                        if (min_depth < 10.f)
                                                                depth[i](v, u) = min_depth;
                                                        else
                                                                depth[i](v, u) = 0.f;
                                                }
                                        }
                                }
                }

                // Calculate coordinates "xy" of the points
                const float inv_f_i = 2.f * tan(0.5f * fovh) / float(cols_i);
                const float disp_u_i = 0.5f * (cols_i - 1);
                const float disp_v_i = 0.5f * (rows_i - 1);

                for (unsigned int u = 0; u < cols_i; u++)
                        for (unsigned int v = 0; v < rows_i; v++)
                                if (depth[i](v, u) > 0.f)
                                {
                                        xx[i](v, u) = (u - disp_u_i) * depth[i](v, u) * inv_f_i;
                                        yy[i](v, u) = (v - disp_v_i) * depth[i](v, u) * inv_f_i;
                                }
                                else
                                {
                                        xx[i](v, u) = 0.f;
                                        yy[i](v, u) = 0.f;
                                }
        }
}

void CDifodo::buildCoordinatesPyramidFast()
{
        const float max_depth_dif = 0.1f;

        // Push coordinates back
        depth_old.swap(depth);
        xx_old.swap(xx);
        yy_old.swap(yy);

        // The number of levels of the pyramid does not match the number of levels
        // used
        // in the odometry computation (because we might want to finish with lower
        // resolutions)

        unsigned int pyr_levels =
                round(log(float(width / cols)) / log(2.f)) + ctf_levels;

        // Generate levels
        for (unsigned int i = 0; i < pyr_levels; i++)
        {
                unsigned int s = pow(2.f, int(i));
                cols_i = width / s;
                rows_i = height / s;
                // const int rows_i2 = 2*rows_i;
                // const int cols_i2 = 2*cols_i;
                const int i_1 = i - 1;

                if (i == 0) depth[i].swap(depth_wf);

                //                              Downsampling
                //-----------------------------------------------------------------------------
                else
                {
                        for (unsigned int u = 0; u < cols_i; u++)
                                for (unsigned int v = 0; v < rows_i; v++)
                                {
                                        const int u2 = 2 * u;
                                        const int v2 = 2 * v;

                                        // Inner pixels
                                        if ((v > 0) && (v < rows_i - 1) && (u > 0) &&
                                                (u < cols_i - 1))
                                        {
                                                const Matrix4f d_block =
                                                        depth[i_1].block<4, 4>(v2 - 1, u2 - 1);
                                                float depths[4] = {d_block(5), d_block(6), d_block(9),
                                                                                   d_block(10)};
                                                float dcenter;

                                                // Sort the array (try to find a good/representative
                                                // value)
                                                for (signed char k = 2; k >= 0; k--)
                                                        if (depths[k + 1] < depths[k])
                                                                std::swap(depths[k + 1], depths[k]);
                                                for (unsigned char k = 1; k < 3; k++)
                                                        if (depths[k] > depths[k + 1])
                                                                std::swap(depths[k + 1], depths[k]);
                                                if (depths[2] < depths[1])
                                                        dcenter = depths[1];
                                                else
                                                        dcenter = depths[2];

                                                if (dcenter > 0.f)
                                                {
                                                        float sum = 0.f;
                                                        float weight = 0.f;

                                                        for (unsigned char k = 0; k < 16; k++)
                                                        {
                                                                const float abs_dif = abs(d_block(k) - dcenter);
                                                                if (abs_dif < max_depth_dif)
                                                                {
                                                                        const float aux_w =
                                                                                f_mask(k) * (max_depth_dif - abs_dif);
                                                                        weight += aux_w;
                                                                        sum += aux_w * d_block(k);
                                                                }
                                                        }
                                                        depth[i](v, u) = sum / weight;
                                                }
                                                else
                                                        depth[i](v, u) = 0.f;
                                        }

                                        // Boundary
                                        else
                                        {
                                                const Matrix2f d_block = depth[i_1].block<2, 2>(v2, u2);
                                                const float new_d = 0.25f * d_block.sumAll();
                                                if (new_d < 0.4f)
                                                        depth[i](v, u) = 0.f;
                                                else
                                                        depth[i](v, u) = new_d;
                                        }
                                }
                }

                // Calculate coordinates "xy" of the points
                const float inv_f_i = 2.f * tan(0.5f * fovh) / float(cols_i);
                const float disp_u_i = 0.5f * (cols_i - 1);
                const float disp_v_i = 0.5f * (rows_i - 1);

                for (unsigned int u = 0; u < cols_i; u++)
                        for (unsigned int v = 0; v < rows_i; v++)
                                if (depth[i](v, u) > 0.f)
                                {
                                        xx[i](v, u) = (u - disp_u_i) * depth[i](v, u) * inv_f_i;
                                        yy[i](v, u) = (v - disp_v_i) * depth[i](v, u) * inv_f_i;
                                }
                                else
                                {
                                        xx[i](v, u) = 0.f;
                                        yy[i](v, u) = 0.f;
                                }
        }
}

void CDifodo::performWarping()
{
        // Camera parameters (which also depend on the level resolution)
        const float f = float(cols_i) / (2.f * tan(0.5f * fovh));
        const float disp_u_i = 0.5f * float(cols_i - 1);
        const float disp_v_i = 0.5f * float(rows_i - 1);

        // Rigid transformation estimated up to the present level
        Matrix4f acu_trans;
        acu_trans.setIdentity();
        for (unsigned int i = 1; i <= level; i++)
                acu_trans = transformations[i - 1] * acu_trans;

        MatrixXf wacu(rows_i, cols_i);
        wacu.assign(0.f);
        depth_warped[image_level].assign(0.f);

        const float cols_lim = float(cols_i - 1);
        const float rows_lim = float(rows_i - 1);

        //                                              Warping loop
        //---------------------------------------------------------
        for (unsigned int j = 0; j < cols_i; j++)
                for (unsigned int i = 0; i < rows_i; i++)
                {
                        const float z = depth[image_level](i, j);

                        if (z > 0.f)
                        {
                                // Transform point to the warped reference frame
                                const float depth_w = acu_trans(0, 0) * z +
                                                                          acu_trans(0, 1) * xx[image_level](i, j) +
                                                                          acu_trans(0, 2) * yy[image_level](i, j) +
                                                                          acu_trans(0, 3);
                                const float x_w = acu_trans(1, 0) * z +
                                                                  acu_trans(1, 1) * xx[image_level](i, j) +
                                                                  acu_trans(1, 2) * yy[image_level](i, j) +
                                                                  acu_trans(1, 3);
                                const float y_w = acu_trans(2, 0) * z +
                                                                  acu_trans(2, 1) * xx[image_level](i, j) +
                                                                  acu_trans(2, 2) * yy[image_level](i, j) +
                                                                  acu_trans(2, 3);

                                // Calculate warping
                                const float uwarp = f * x_w / depth_w + disp_u_i;
                                const float vwarp = f * y_w / depth_w + disp_v_i;

                                // The warped pixel (which is not integer in general)
                                // contributes to all the surrounding ones
                                if ((uwarp >= 0.f) && (uwarp < cols_lim) && (vwarp >= 0.f) &&
                                        (vwarp < rows_lim))
                                {
                                        const int uwarp_l = uwarp;
                                        const int uwarp_r = uwarp_l + 1;
                                        const int vwarp_d = vwarp;
                                        const int vwarp_u = vwarp_d + 1;
                                        const float delta_r = float(uwarp_r) - uwarp;
                                        const float delta_l = uwarp - float(uwarp_l);
                                        const float delta_u = float(vwarp_u) - vwarp;
                                        const float delta_d = vwarp - float(vwarp_d);

                                        // Warped pixel very close to an integer value
                                        if (abs(round(uwarp) - uwarp) + abs(round(vwarp) - vwarp) <
                                                0.05f)
                                        {
                                                depth_warped[image_level](round(vwarp), round(uwarp)) +=
                                                        depth_w;
                                                wacu(round(vwarp), round(uwarp)) += 1.f;
                                        }
                                        else
                                        {
                                                const float w_ur = square(delta_l) + square(delta_d);
                                                depth_warped[image_level](vwarp_u, uwarp_r) +=
                                                        w_ur * depth_w;
                                                wacu(vwarp_u, uwarp_r) += w_ur;

                                                const float w_ul = square(delta_r) + square(delta_d);
                                                depth_warped[image_level](vwarp_u, uwarp_l) +=
                                                        w_ul * depth_w;
                                                wacu(vwarp_u, uwarp_l) += w_ul;

                                                const float w_dr = square(delta_l) + square(delta_u);
                                                depth_warped[image_level](vwarp_d, uwarp_r) +=
                                                        w_dr * depth_w;
                                                wacu(vwarp_d, uwarp_r) += w_dr;

                                                const float w_dl = square(delta_r) + square(delta_u);
                                                depth_warped[image_level](vwarp_d, uwarp_l) +=
                                                        w_dl * depth_w;
                                                wacu(vwarp_d, uwarp_l) += w_dl;
                                        }
                                }
                        }
                }

        // Scale the averaged depth and compute spatial coordinates
        const float inv_f_i = 1.f / f;
        for (unsigned int u = 0; u < cols_i; u++)
                for (unsigned int v = 0; v < rows_i; v++)
                {
                        if (wacu(v, u) > 0.f)
                        {
                                depth_warped[image_level](v, u) /= wacu(v, u);
                                xx_warped[image_level](v, u) =
                                        (u - disp_u_i) * depth_warped[image_level](v, u) * inv_f_i;
                                yy_warped[image_level](v, u) =
                                        (v - disp_v_i) * depth_warped[image_level](v, u) * inv_f_i;
                        }
                        else
                        {
                                depth_warped[image_level](v, u) = 0.f;
                                xx_warped[image_level](v, u) = 0.f;
                                yy_warped[image_level](v, u) = 0.f;
                        }
                }
}

void CDifodo::calculateCoord()
{
        null.resize(rows_i, cols_i);
        null.assign(false);
        num_valid_points = 0;

        for (unsigned int u = 0; u < cols_i; u++)
                for (unsigned int v = 0; v < rows_i; v++)
                {
                        if ((depth_old[image_level](v, u)) == 0.f ||
                                (depth_warped[image_level](v, u) == 0.f))
                        {
                                depth_inter[image_level](v, u) = 0.f;
                                xx_inter[image_level](v, u) = 0.f;
                                yy_inter[image_level](v, u) = 0.f;
                                null(v, u) = true;
                        }
                        else
                        {
                                depth_inter[image_level](v, u) =
                                        0.5f * (depth_old[image_level](v, u) +
                                                        depth_warped[image_level](v, u));
                                xx_inter[image_level](v, u) =
                                        0.5f *
                                        (xx_old[image_level](v, u) + xx_warped[image_level](v, u));
                                yy_inter[image_level](v, u) =
                                        0.5f *
                                        (yy_old[image_level](v, u) + yy_warped[image_level](v, u));
                                null(v, u) = false;
                                if ((u > 0) && (v > 0) && (u < cols_i - 1) && (v < rows_i - 1))
                                        num_valid_points++;
                        }
                }
}

void CDifodo::calculateDepthDerivatives()
{
        dt.resize(rows_i, cols_i);
        dt.assign(0.f);
        du.resize(rows_i, cols_i);
        du.assign(0.f);
        dv.resize(rows_i, cols_i);
        dv.assign(0.f);

        // Compute connectivity
        MatrixXf rx_ninv(rows_i, cols_i);
        MatrixXf ry_ninv(rows_i, cols_i);
        rx_ninv.assign(1.f);
        ry_ninv.assign(1.f);

        for (unsigned int u = 0; u < cols_i - 1; u++)
                for (unsigned int v = 0; v < rows_i; v++)
                        if (null(v, u) == false)
                        {
                                rx_ninv(v, u) = sqrtf(
                                        square(
                                                xx_inter[image_level](v, u + 1) -
                                                xx_inter[image_level](v, u)) +
                                        square(
                                                depth_inter[image_level](v, u + 1) -
                                                depth_inter[image_level](v, u)));
                        }

        for (unsigned int u = 0; u < cols_i; u++)
                for (unsigned int v = 0; v < rows_i - 1; v++)
                        if (null(v, u) == false)
                        {
                                ry_ninv(v, u) = sqrtf(
                                        square(
                                                yy_inter[image_level](v + 1, u) -
                                                yy_inter[image_level](v, u)) +
                                        square(
                                                depth_inter[image_level](v + 1, u) -
                                                depth_inter[image_level](v, u)));
                        }

        // Spatial derivatives
        for (unsigned int v = 0; v < rows_i; v++)
        {
                for (unsigned int u = 1; u < cols_i - 1; u++)
                        if (null(v, u) == false)
                                du(v, u) =
                                        (rx_ninv(v, u - 1) * (depth_inter[image_level](v, u + 1) -
                                                                                  depth_inter[image_level](v, u)) +
                                         rx_ninv(v, u) * (depth_inter[image_level](v, u) -
                                                                          depth_inter[image_level](v, u - 1))) /
                                        (rx_ninv(v, u) + rx_ninv(v, u - 1));

                du(v, 0) = du(v, 1);
                du(v, cols_i - 1) = du(v, cols_i - 2);
        }

        for (unsigned int u = 0; u < cols_i; u++)
        {
                for (unsigned int v = 1; v < rows_i - 1; v++)
                        if (null(v, u) == false)
                                dv(v, u) =
                                        (ry_ninv(v - 1, u) * (depth_inter[image_level](v + 1, u) -
                                                                                  depth_inter[image_level](v, u)) +
                                         ry_ninv(v, u) * (depth_inter[image_level](v, u) -
                                                                          depth_inter[image_level](v - 1, u))) /
                                        (ry_ninv(v, u) + ry_ninv(v - 1, u));

                dv(0, u) = dv(1, u);
                dv(rows_i - 1, u) = dv(rows_i - 2, u);
        }

        // Temporal derivative
        for (unsigned int u = 0; u < cols_i; u++)
                for (unsigned int v = 0; v < rows_i; v++)
                        if (null(v, u) == false)
                                dt(v, u) = fps * (depth_warped[image_level](v, u) -
                                                                  depth_old[image_level](v, u));
}

void CDifodo::computeWeights()
{
        weights.resize(rows_i, cols_i);
        weights.assign(0.f);

        // Obtain the velocity associated to the rigid transformation estimated up
        // to the present level
        Matrix<float, 6, 1> kai_level = kai_loc_old;

        Matrix4f acu_trans;
        acu_trans.setIdentity();
        for (unsigned int i = 0; i < level; i++)
                acu_trans = transformations[i] * acu_trans;

        // Alternative way to compute the log
        CMatrixDouble44 mat_aux = acu_trans.cast<double>();
        poses::CPose3D aux(mat_aux);
        CArrayDouble<6> kai_level_acu = aux.ln() * fps;
        kai_level -= kai_level_acu.cast<float>();

        // Parameters for the measurement error
        const float f_inv = float(cols_i) / (2.f * tan(0.5f * fovh));
        const float kz2 = 8.122e-12f;  // square(1.425e-5) / 25

        // Parameters for linearization error
        const float kduv = 20e-5f;
        const float kdt = kduv / square(fps);
        const float k2dt = 5e-6f;
        const float k2duv = 5e-6f;

        for (unsigned int u = 1; u < cols_i - 1; u++)
                for (unsigned int v = 1; v < rows_i - 1; v++)
                        if (null(v, u) == false)
                        {
                                //                                      Compute measurment error (simplified)
                                //-----------------------------------------------------------------------
                                const float z = depth_inter[image_level](v, u);
                                const float inv_d = 1.f / z;
                                // const float dycomp = du2(v,u)*f_inv_y*inv_d;
                                // const float dzcomp = dv2(v,u)*f_inv_z*inv_d;
                                const float z2 = z * z;
                                const float z4 = z2 * z2;

                                // const float var11 = kz2*z4;
                                // const float var12 =
                                // kz2*xx_inter[image_level](v,u)*z2*depth_inter[image_level](v,u);
                                // const float var13 =
                                // kz2*yy_inter[image_level](v,u)*z2*depth_inter[image_level](v,u);
                                // const float var22 =
                                // kz2*square(xx_inter[image_level](v,u))*z2;
                                // const float var23 =
                                // kz2*xx_inter[image_level](v,u)*yy_inter[image_level](v,u)*z2;
                                // const float var33 =
                                // kz2*square(yy_inter[image_level](v,u))*z2;
                                const float var44 = kz2 * z4 * square(fps);
                                const float var55 = kz2 * z4 * 0.25f;
                                const float var66 = var55;

                                // const float j1 =
                                // -2.f*inv_d*inv_d*(xx_inter[image_level](v,u)*dycomp +
                                // yy_inter[image_level](v,u)*dzcomp)*(kai_level[0] +
                                // yy_inter[image_level](v,u)*kai_level[4] -
                                // xx_inter[image_level](v,u)*kai_level[5])
                                //                              + inv_d*dycomp*(kai_level[1] -
                                // yy_inter[image_level](v,u)*kai_level[3]) +
                                // inv_d*dzcomp*(kai_level[2] +
                                // xx_inter[image_level](v,u)*kai_level[3]);
                                // const float j2 = inv_d*dycomp*(kai_level[0] +
                                // yy_inter[image_level](v,u)*kai_level[4] -
                                // 2.f*xx_inter[image_level](v,u)*kai_level[5]) -
                                // dzcomp*kai_level[3];
                                // const float j3 = inv_d*dzcomp*(kai_level[0] +
                                // 2.f*yy_inter[image_level](v,u)*kai_level[4] -
                                // xx_inter[image_level](v,u)*kai_level[5]) +
                                // dycomp*kai_level[3];

                                const float j4 = 1.f;
                                const float j5 =
                                        xx_inter[image_level](v, u) * inv_d * inv_d * f_inv *
                                                (kai_level[0] +
                                                 yy_inter[image_level](v, u) * kai_level[4] -
                                                 xx_inter[image_level](v, u) * kai_level[5]) +
                                        inv_d * f_inv *
                                                (-kai_level[1] - z * kai_level[5] +
                                                 yy_inter[image_level](v, u) * kai_level[3]);
                                const float j6 =
                                        yy_inter[image_level](v, u) * inv_d * inv_d * f_inv *
                                                (kai_level[0] +
                                                 yy_inter[image_level](v, u) * kai_level[4] -
                                                 xx_inter[image_level](v, u) * kai_level[5]) +
                                        inv_d * f_inv *
                                                (-kai_level[2] + z * kai_level[4] -
                                                 xx_inter[image_level](v, u) * kai_level[3]);

                                // error_measurement(v,u) = j1*(j1*var11+j2*var12+j3*var13) +
                                // j2*(j1*var12+j2*var22+j3*var23)
                                //                                              +j3*(j1*var13+j2*var23+j3*var33) +
                                // j4*j4*var44
                                //+
                                // j5*j5*var55 + j6*j6*var66;

                                const float error_m =
                                        j4 * j4 * var44 + j5 * j5 * var55 + j6 * j6 * var66;

                                //                                      Compute linearization error
                                //-----------------------------------------------------------------------
                                const float ini_du = depth_old[image_level](v, u + 1) -
                                                                         depth_old[image_level](v, u - 1);
                                const float ini_dv = depth_old[image_level](v + 1, u) -
                                                                         depth_old[image_level](v - 1, u);
                                const float final_du = depth_warped[image_level](v, u + 1) -
                                                                           depth_warped[image_level](v, u - 1);
                                const float final_dv = depth_warped[image_level](v + 1, u) -
                                                                           depth_warped[image_level](v - 1, u);

                                const float dut = ini_du - final_du;
                                const float dvt = ini_dv - final_dv;
                                const float duu = du(v, u + 1) - du(v, u - 1);
                                const float dvv = dv(v + 1, u) - dv(v - 1, u);
                                const float dvu =
                                        dv(v, u + 1) -
                                        dv(v, u - 1);  // Completely equivalent to compute duv

                                const float error_l =
                                        kdt * square(dt(v, u)) +
                                        kduv * (square(du(v, u)) + square(dv(v, u))) +
                                        k2dt * (square(dut) + square(dvt)) +
                                        k2duv * (square(duu) + square(dvv) + square(dvu));

                                // Weight
                                weights(v, u) = sqrt(1.f / (error_m + error_l));
                        }

        // Normalize weights in the range [0,1]
        const float inv_max = 1.f / weights.maximum();
        weights = inv_max * weights;
}

void CDifodo::solveOneLevel()
{
        MatrixXf A(num_valid_points, 6);
        MatrixXf B(num_valid_points, 1);
        unsigned int cont = 0;

        // Fill the matrix A and the vector B
        // The order of the unknowns is (vz, vx, vy, wz, wx, wy)
        // The points order will be (1,1), (1,2)...(1,cols-1), (2,1),
        // (2,2)...(row-1,cols-1).

        const float f_inv = float(cols_i) / (2.f * tan(0.5f * fovh));

        for (unsigned int u = 1; u < cols_i - 1; u++)
                for (unsigned int v = 1; v < rows_i - 1; v++)
                        if (null(v, u) == false)
                        {
                                // Precomputed expressions
                                const float d = depth_inter[image_level](v, u);
                                const float inv_d = 1.f / d;
                                const float x = xx_inter[image_level](v, u);
                                const float y = yy_inter[image_level](v, u);
                                const float dycomp = du(v, u) * f_inv * inv_d;
                                const float dzcomp = dv(v, u) * f_inv * inv_d;
                                const float tw = weights(v, u);

                                // Fill the matrix A
                                A(cont, 0) =
                                        tw * (1.f + dycomp * x * inv_d + dzcomp * y * inv_d);
                                A(cont, 1) = tw * (-dycomp);
                                A(cont, 2) = tw * (-dzcomp);
                                A(cont, 3) = tw * (dycomp * y - dzcomp * x);
                                A(cont, 4) = tw * (y + dycomp * inv_d * y * x +
                                                                   dzcomp * (y * y * inv_d + d));
                                A(cont, 5) = tw * (-x - dycomp * (x * x * inv_d + d) -
                                                                   dzcomp * inv_d * y * x);
                                B(cont, 0) = tw * (-dt(v, u));

                                cont++;
                        }

        // Solve the linear system of equations using weighted least squares
        MatrixXf AtA, AtB;
        AtA.multiply_AtA(A);
        AtB.multiply_AtB(A, B);
        MatrixXf Var = AtA.ldlt().solve(AtB);

        // Covariance matrix calculation
        MatrixXf res = -B;
        for (unsigned int k = 0; k < 6; k++) res += Var(k) * A.col(k);

        est_cov =
                (1.f / float(num_valid_points - 6)) * AtA.inverse() * res.squaredNorm();

        // Update last velocity in local coordinates
        kai_loc_level = Var;
}

void CDifodo::odometryCalculation()
{
        // Clock to measure the runtime
        utils::CTicTac clock;
        clock.Tic();

        // Build the gaussian pyramid
        if (fast_pyramid)
                buildCoordinatesPyramidFast();
        else
                buildCoordinatesPyramid();

        // Coarse-to-fines scheme
        for (unsigned int i = 0; i < ctf_levels; i++)
        {
                // Previous computations
                transformations[i].setIdentity();

                level = i;
                unsigned int s = pow(2.f, int(ctf_levels - (i + 1)));
                cols_i = cols / s;
                rows_i = rows / s;
                image_level =
                        ctf_levels - i + round(log(float(width / cols)) / log(2.f)) - 1;

                // 1. Perform warping
                if (i == 0)
                {
                        depth_warped[image_level] = depth[image_level];
                        xx_warped[image_level] = xx[image_level];
                        yy_warped[image_level] = yy[image_level];
                }
                else
                        performWarping();

                // 2. Calculate inter coords and find null measurements
                calculateCoord();

                // 3. Compute derivatives
                calculateDepthDerivatives();

                // 4. Compute weights
                computeWeights();

                // 5. Solve odometry
                if (num_valid_points > 6) solveOneLevel();

                // 6. Filter solution
                filterLevelSolution();
        }

        // Update poses
        poseUpdate();

        // Save runtime
        execution_time = 1000.f * clock.Tac();
}

void CDifodo::filterLevelSolution()
{
        //              Calculate Eigenvalues and Eigenvectors
        //----------------------------------------------------------
        SelfAdjointEigenSolver<MatrixXf> eigensolver(est_cov);
        if (eigensolver.info() != Success)
        {
                printf("\n Eigensolver couldn't find a solution. Pose is not updated");
                return;
        }

        // First, we have to describe both the new linear and angular velocities in
        // the "eigenvector" basis
        //-------------------------------------------------------------------------------------------------
        Matrix<float, 6, 6> Bii;
        Matrix<float, 6, 1> kai_b;
        Bii = eigensolver.eigenvectors();
        kai_b = Bii.colPivHouseholderQr().solve(kai_loc_level);

        // Second, we have to describe both the old linear and angular velocities in
        // the "eigenvector" basis
        //-------------------------------------------------------------------------------------------------
        Matrix<float, 6, 1> kai_loc_sub = kai_loc_old;

        // Important: we have to substract the previous levels' solutions from the
        // old velocity.
        Matrix4f acu_trans;
        acu_trans.setIdentity();
        for (unsigned int i = 0; i < level; i++)
                acu_trans = transformations[i] * acu_trans;

        CMatrixDouble44 mat_aux = acu_trans.cast<double>();
        poses::CPose3D aux(mat_aux);
        CArrayDouble<6> kai_level_acu = aux.ln() * fps;
        kai_loc_sub -= kai_level_acu.cast<float>();

        // Matrix<float, 4, 4> log_trans = fps*acu_trans.log();
        // kai_loc_sub(0) -= log_trans(0,3); kai_loc_sub(1) -= log_trans(1,3);
        // kai_loc_sub(2) -= log_trans(2,3);
        // kai_loc_sub(3) += log_trans(1,2); kai_loc_sub(4) -= log_trans(0,2);
        // kai_loc_sub(5) += log_trans(0,1);

        // Transform that local representation to the "eigenvector" basis
        Matrix<float, 6, 1> kai_b_old;
        kai_b_old = Bii.colPivHouseholderQr().solve(kai_loc_sub);

        //                                                                      Filter velocity
        //--------------------------------------------------------------------------------
        const float cf = previous_speed_eig_weight * expf(-int(level)),
                                df = previous_speed_const_weight * expf(-int(level));
        Matrix<float, 6, 1> kai_b_fil;
        for (unsigned int i = 0; i < 6; i++)
                kai_b_fil(i) =
                        (kai_b(i) +
                         (cf * eigensolver.eigenvalues()(i, 0) + df) * kai_b_old(i)) /
                        (1.f + cf * eigensolver.eigenvalues()(i) + df);

        // Transform filtered velocity to the local reference frame
        Matrix<float, 6, 1> kai_loc_fil =
                Bii.inverse().colPivHouseholderQr().solve(kai_b_fil);

        // Compute the rigid transformation
        mrpt::math::CArrayDouble<6> aux_vel = kai_loc_fil.cast<double>() / fps;
        poses::CPose3D aux1, aux2;
        CMatrixDouble44 trans;
        aux2 = aux1.exp(aux_vel);
        aux2.getHomogeneousMatrix(trans);
        transformations[level] = trans.cast<float>();
}

void CDifodo::poseUpdate()
{
        // First, compute the overall transformation
        //---------------------------------------------------
        Matrix4f acu_trans;
        acu_trans.setIdentity();
        for (unsigned int i = 1; i <= ctf_levels; i++)
                acu_trans = transformations[i - 1] * acu_trans;

        // Compute the new estimates in the local and absolutes reference frames
        //---------------------------------------------------------------------
        CMatrixDouble44 mat_aux = acu_trans.cast<double>();
        poses::CPose3D aux(mat_aux);
        CArrayDouble<6> kai_level_acu = aux.ln() * fps;
        kai_loc = kai_level_acu.cast<float>();

        //---------------------------------------------------------------------------------------------
        // Directly from Eigen:
        //- Eigen 3.1.0 needed for Matrix::log()
        //- The line "#include <unsupported/Eigen/MatrixFunctions>" should be
        // uncommented (CDifodo.h)
        //
        // Matrix<float, 4, 4> log_trans = fps*acu_trans.log();
        // kai_loc(0) = log_trans(0,3); kai_loc(1) = log_trans(1,3); kai_loc(2) =
        // log_trans(2,3);
        // kai_loc(3) = -log_trans(1,2); kai_loc(4) = log_trans(0,2); kai_loc(5) =
        // -log_trans(0,1);
        //---------------------------------------------------------------------------------------------

        CMatrixDouble33 inv_trans;
        CMatrixFloat31 v_abs, w_abs;

        cam_pose.getRotationMatrix(inv_trans);
        v_abs = inv_trans.cast<float>() * kai_loc.topRows(3);
        w_abs = inv_trans.cast<float>() * kai_loc.bottomRows(3);
        kai_abs.topRows<3>() = v_abs;
        kai_abs.bottomRows<3>() = w_abs;

        //                                              Update poses
        //-------------------------------------------------------
        cam_oldpose = cam_pose;
        CMatrixDouble44 aux_acu = acu_trans;
        poses::CPose3D pose_aux(aux_acu);
        cam_pose = cam_pose + pose_aux;

        // Compute the velocity estimate in the new ref frame (to be used by the
        // filter in the next iteration)
        //---------------------------------------------------------------------------------------------------
        cam_pose.getRotationMatrix(inv_trans);
        kai_loc_old.topRows<3>() =
                inv_trans.inverse().cast<float>() * kai_abs.topRows(3);
        kai_loc_old.bottomRows<3>() =
                inv_trans.inverse().cast<float>() * kai_abs.bottomRows(3);
}

void CDifodo::setFOV(float new_fovh, float new_fovv)
{
        fovh = M_PI * new_fovh / 180.0;
        fovv = M_PI * new_fovv / 180.0;
}

void CDifodo::getPointsCoord(MatrixXf& x, MatrixXf& y, MatrixXf& z)
{
        x.resize(rows, cols);
        y.resize(rows, cols);
        z.resize(rows, cols);

        z = depth_inter[0];
        x = xx_inter[0];
        y = yy_inter[0];
}

void CDifodo::getDepthDerivatives(
        MatrixXf& cur_du, MatrixXf& cur_dv, MatrixXf& cur_dt)
{
        cur_du.resize(rows, cols);
        cur_dv.resize(rows, cols);
        cur_dt.resize(rows, cols);

        cur_du = du;
        cur_dv = dv;
        cur_dt = dt;
}

void CDifodo::getWeights(MatrixXf& w)
{
        w.resize(rows, cols);
        w = weights;
}