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 <optional>
#include <vector>
 
#include "Eigen/Core"
 
#include "lsst/afw/geom/SkyWcs.h"
#include "lsst/geom/Box.h"
#include "lsst/geom/LinearTransform.h"
 
namespace lsst { namespace afw { namespace geom {

class SipApproximation final {
public:

    SipApproximation(
        SkyWcs const & target,
        lsst::geom::Box2D const & bbox,
        lsst::geom::Extent2I const & gridShape,
        int order = 5,
        std::optional<lsst::geom::Point2D> const & pixelOrigin = std::nullopt,
        double svdThreshold=-1
    );
 
    // 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;

    Eigen::MatrixXd getA() const;

    Eigen::MatrixXd getB() const;

    lsst::geom::Box2D getBBox() const noexcept { return _bbox; }

    lsst::geom::SpherePoint getSkyOrigin() const noexcept { return _skyOrigin; }

    lsst::geom::Point2D getPixelOrigin() const noexcept { return lsst::geom::Point2D(_pixelOrigin); }

    Eigen::Matrix2d getCdMatrix() const noexcept;

    std::shared_ptr<SkyWcs> getWcs() const noexcept;

    std::pair<lsst::geom::Angle, double> computeDeltas() const;
 
private:
 
    struct FitGrid;
    struct ValidationGrid;
    struct Solution;
 
    lsst::geom::Box2D _bbox;
    lsst::geom::Point2D _pixelOrigin;
    lsst::geom::SpherePoint _skyOrigin;
    std::unique_ptr<FitGrid const> _fitGrid;
    std::unique_ptr<ValidationGrid const> _validationGrid;
    std::unique_ptr<Solution const> _solution;
    std::shared_ptr<SkyWcs> _wcs;
};
 
}}}  // namespace lsst::afw::geom
 
#endif // !LSST_AFW_GEOM_SipApproximation_h_INCLUDED