Re: [Boost-users] catmull_rom returning a single point

Hi there, You will need to normalise (0 - 1) your data set first. To interpolate, you will need to pass normalised values, as well. Then you can unscale the output in the range you want. On Mon, Sep 30, 2019 at 1:51 AM hgrwilson via Boost-users < boost-users@lists.boost.org> wrote:

Hi all,

I am trying to interpolate some data with a *catmull_rom* spline available in boost math (interpolation). However, the resulting spline collapses to a single point for all /s/, corresponding to the first control point, /points_intr[0]/.

Below, the c++ code segment of the interpolation is depicted:

std::vector> points_intr(16);

points_intr[0] = { 1.263270, 0.774614 }; points_intr[1] = { 1.876, 2.480 }; points_intr[2] = { 1.651110, 4.550 }; points_intr[3] = { 1.426340, 5.688 }; points_intr[4] = { 1.429, 7.054 }; points_intr[5] = { 2.073220, 8.377020 }; points_intr[6] = { 3.910, 9.140 }; points_intr[7] = { 6.430, 9.537 }; points_intr[8] = { 8.950, 9.859 }; points_intr[9] = { 11.470, 10.317 }; points_intr[10] = { 12.730, 10.6456 }; points_intr[11] = { 13.990, 11.0741 }; points_intr[12] = { 15.335, 11.6928 }; points_intr[13] = { 16.680, 12.5661 }; points_intr[14] = { 18.3538, 14.830 }; points_intr[15] = { 18.700, 16.056 };

boost::math::catmull_rom> interpolator_cr(std::move(points_intr));

auto max_s = interpolator_cr.max_parameter(); std::array inter_points; for (int i = 0; i < 100; i++) { inter_points = interpolator_cr(max_s * (i / num_points)); geometry_msgs::Point p; p.x = inter_points[0]; p.y = inter_points[1]; p.z = z; //p.z = inter_points[2]; marker.points.push_back(p); DEBUG_INFO("spline %d: (x, y) %f, %f, current_s: %f", i, p.x, p.y, max_s * (i / 100.0)); }

I'm using boost 1.71.0

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