SipApproximation.h

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// -*- lsst-c++ -*-
/*
 * Developed for the LSST Data Management System.
 * This product includes software developed by the LSST Project
 * (https://www.lsst.org).
 * See the COPYRIGHT file at the top-level directory of this distribution
 * for details of code ownership.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef LSST_AFW_GEOM_SipApproximation_h_INCLUDED
#define LSST_AFW_GEOM_SipApproximation_h_INCLUDED

#include <memory>
#include <vector>

#include "Eigen/Core"

#include "lsst/afw/geom/Transform.h"
#include "lsst/afw/geom/Box.h"
#include "lsst/afw/geom/LinearTransform.h"

namespace lsst { namespace afw { namespace geom {

class SipApproximation final {
public:

    SipApproximation(
        std::shared_ptr<TransformPoint2ToPoint2> pixelToIwc,
        Point2D const & crpix,
        Eigen::Matrix2d const & cd,
        Box2D const & bbox,
        Extent2I const & gridShape,
        int order,
        bool useInverse=true,
        double svdThreshold=-1
    );

    SipApproximation(
        std::shared_ptr<TransformPoint2ToPoint2> pixelToIwc,
        Point2D const & crpix,
        Eigen::Matrix2d const & cd,
        Box2D const & bbox,
        Extent2I const & gridShape,
        ndarray::Array<double const, 2> const & a,
        ndarray::Array<double const, 2> const & b,
        ndarray::Array<double const, 2> const & ap,
        ndarray::Array<double const, 2> const & bp,
        bool useInverse=true
    );

    // No copies just because they'd be a pain to implement and probably aren't necessary
    SipApproximation(SipApproximation const &) = delete;
    SipApproximation & operator=(SipApproximation const &) = delete;

    // Moves are fine.
    SipApproximation(SipApproximation &&) noexcept = default;
    SipApproximation & operator=(SipApproximation &&) noexcept = default;

    // Needs to be defined in .cc, where compiler can see the definitions of forward-declared
    // private implementation classes.
    ~SipApproximation() noexcept;

    int getOrder() const noexcept;

    double getA(int p, int q) const;

    double getB(int p, int q) const;

    double getAP(int p, int q) const;

    double getBP(int p, int q) const;

    Eigen::MatrixXd getA() const noexcept;

    Eigen::MatrixXd getB() const noexcept;

    Eigen::MatrixXd getAP() const noexcept;

    Eigen::MatrixXd getBP() const noexcept;

    Point2D applyForward(Point2D const & pix) const;

    std::vector<Point2D> applyForward(std::vector<Point2D> const & pix) const;

    Point2D applyInverse(Point2D const & iwcs) const;

    std::vector<Point2D> applyInverse(std::vector<Point2D> const & iwcs) const;

    Extent2D getGridStep() const noexcept;

    Extent2I getGridShape() const noexcept;

    Box2D getBBox() const noexcept { return _bbox; }

    Point2D getPixelOrigin() const noexcept { return Point2D(_crpix); }

    Eigen::Matrix2d getCdMatrix() const noexcept { return _cdInv.inverted().getMatrix(); }

    void updateGrid(Extent2I const & shape);

    void refineGrid(int factor=2);

    void fit(int order, double svdThreshold=-1);

    std::pair<double, double> computeMaxDeviation() const noexcept;

private:

    struct Grid;
    struct Solution;

    bool _useInverse;
    std::shared_ptr<TransformPoint2ToPoint2> _pixelToIwc;
    Box2D _bbox;
    Extent2D _crpix;
    LinearTransform _cdInv;
    std::unique_ptr<Grid const> _grid;
    std::unique_ptr<Solution const> _solution;
};

}}}  // namespace lsst::afw::geom

#endif // !LSST_AFW_GEOM_SipApproximation_h_INCLUDED