exampleUtil.cpp

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/*
 * exampleUtil.cpp
 *
 *  Created on: 6 Nov 2018
 *      Author: kleinwrt
 */
 
#include "exampleUtil.h"
 
using namespace Eigen;
 
namespace gbl {
 
typedef Eigen::Matrix<double, 5, 5> Matrix5d;
 
 
double gblMultipleScatteringError(double qbyp, double xbyx0) {
        return 0.015 * fabs(qbyp) * sqrt(xbyx0);
}
 
 
Matrix5d gblSimpleJacobian(double ds, double cosl, double bfac) {
        Matrix5d jac;
        jac.setIdentity();
        jac(1, 0) = -bfac * ds * cosl;
        jac(3, 0) = -0.5 * bfac * ds * ds * cosl;
        jac(3, 1) = ds;
        jac(4, 2) = ds;
        return jac;
}
 
double unrm() {
        static double unrm2 = 0.0;
        static bool cached = false;
        if (!cached) {
                double x, y, r;
                do {
                        x = 2.0 * static_cast<double>(rand())
                                        / static_cast<double>(RAND_MAX) - 1;
                        y = 2.0 * static_cast<double>(rand())
                                        / static_cast<double>(RAND_MAX) - 1;
                        r = x * x + y * y;
                } while (r == 0.0 || r > 1.0);
                // (x,y) in unit circle
                double d = sqrt(-2.0 * log(r) / r);
                double unrm1 = x * d;
                unrm2 = y * d;
                cached = true;
                return unrm1;
        } else {
                cached = false;
                return unrm2;
        }
}
 
double unif() {
        return static_cast<double>(rand()) / static_cast<double>(RAND_MAX);
}
 
 
GblHelixPrediction::GblHelixPrediction(double sArc, const Vector2d& aPred,
                const Vector3d& tDir, const Vector3d& uDir, const Vector3d& vDir,
                const Vector3d& nDir, const Vector3d& aPos) :
                sarc(sArc), pred(aPred), tdir(tDir), udir(uDir), vdir(vDir), ndir(nDir), pos(
                                aPos) {
        global2meas << uDir.transpose(), vDir.transpose(), nDir.transpose();
}
 
GblHelixPrediction::~GblHelixPrediction() {
}
 
double GblHelixPrediction::getArcLength() const {
        return sarc;
}
 
const Vector2d& GblHelixPrediction::getMeasPred() const {
        return pred;
}
 
const Vector3d& GblHelixPrediction::getPosition() const {
        return pos;
}
 
const Vector3d& GblHelixPrediction::getDirection() const {
        return tdir;
}
 
double GblHelixPrediction::getCosIncidence() const {
        return tdir.dot(ndir);
}
 
/*
 * Curvilinear system: track direction T, U = Z x T / |Z x T|, V = T x U
 */
Eigen::Matrix<double, 2, 3> GblHelixPrediction::getCurvilinearDirs() const {
        const double cosTheta = tdir[2];
        const double sinTheta = sqrt(tdir[0] * tdir[0] + tdir[1] * tdir[1]);
        const double cosPhi = tdir[0] / sinTheta;
        const double sinPhi = tdir[1] / sinTheta;
        Eigen::Matrix<double, 2, 3> uvDir;
        uvDir << -sinPhi, cosPhi, 0., -cosPhi * cosTheta, -sinPhi * cosTheta, sinTheta;
        return uvDir;
}
 
 
GblSimpleHelix::GblSimpleHelix(double aRinv, double aPhi0, double aDca,
                double aDzds, double aZ0) :
                rinv(aRinv), phi0(aPhi0), dca(aDca), dzds(aDzds), z0(aZ0), cosPhi0(
                                cos(phi0)), sinPhi0(sin(phi0)), xRelCenter(
                                -(1. - dca * rinv) * sinPhi0), yRelCenter(
                                (1. - dca * rinv) * cosPhi0) {
}
 
GblSimpleHelix::~GblSimpleHelix() {
}
 
 
double GblSimpleHelix::getPhi(double aRadius) const {
        double arg = (0.5 * rinv * (aRadius * aRadius + dca * dca) - dca)
                        / (aRadius * (1.0 - rinv * dca));
        return asin(arg) + phi0;
}
 
 
double GblSimpleHelix::getArcLengthR(double aRadius) const {
        double arg = (0.5 * rinv * (aRadius * aRadius + dca * dca) - dca)
                        / (aRadius * (1.0 - rinv * dca));
        if (fabs(arg) >= 1.) {
                std::cout << " bad arc " << aRadius << " " << rinv << " " << dca
                                << std::endl;
                return 0.;
        }
        // line
        if (rinv == 0)
                return sqrt(aRadius * aRadius - dca * dca);
        // helix
        double sxy = asin(aRadius * rinv * sqrt(1.0 - arg * arg)) / rinv;
        if (0.5 * rinv * rinv * (aRadius * aRadius - dca * dca) - 1. + rinv * dca
                        > 0.)
                sxy = M_PI / fabs(rinv) - sxy;
        return sxy;
}
 
 
double GblSimpleHelix::getArcLengthXY(double xPos, double yPos) const {
// line
        if (rinv == 0)
                return cosPhi0 * xPos + sinPhi0 * yPos;
// helix
        double dx = xPos * rinv - xRelCenter;
        double dy = yPos * rinv - yRelCenter;
        double dphi = atan2(dx, -dy) - phi0;
        if (dphi > M_PI)
                dphi -= 2.0 * M_PI;
        else if (dphi < -M_PI)
                dphi += 2.0 * M_PI;
        return dphi / rinv;
}
 
 
void GblSimpleHelix::moveToXY(double xPos, double yPos, double& newPhi0,
                double& newDca, double& newZ0) const {
// start values
        newPhi0 = phi0;
        newDca = dca;
        newZ0 = z0;
// Based on V. Karimaki, NIM A305 (1991) 187-191, eqn (19)
        const double u = 1. - rinv * dca;
        const double dp = -xPos * sinPhi0 + yPos * cosPhi0 + dca;
        const double dl = xPos * cosPhi0 + yPos * sinPhi0;
        const double sa = 2. * dp - rinv * (dp * dp + dl * dl);
        const double sb = rinv * xPos + u * sinPhi0;
        const double sc = -rinv * yPos + u * cosPhi0;
        const double sd = sqrt(1. - rinv * sa);
// transformed parameters
        double sArc;
        if (rinv == 0.) {
                newDca = dp;
                sArc = dl;
        } else {
                newPhi0 = atan2(sb, sc);
                newDca = sa / (1. + sd);
                double dphi = newPhi0 - phi0;
                if (dphi > M_PI)
                        dphi -= 2.0 * M_PI;
                else if (dphi < -M_PI)
                        dphi += 2.0 * M_PI;
                sArc = dphi / rinv;
        }
        newZ0 += sArc * dzds;
}
 
/*
 * \param [in] refPos  reference position on detector plane
 * \param [in] uDir    measurement direction 'u'
 * \param [in] vDir    measurement direction 'v'
 */
GblHelixPrediction GblSimpleHelix::getPrediction(const Eigen::Vector3d& refPos,
                const Eigen::Vector3d& uDir, const Eigen::Vector3d& vDir) const {
// normal to (u,v) measurement plane
        Vector3d nDir = uDir.cross(vDir).normalized();
// ZS direction
        const double cosLambda = 1. / sqrt(1. + dzds * dzds);
        const double sinLambda = dzds * cosLambda;
        double sArc2D;
        Vector3d dist, pos, tDir;
// line (or helix)
        if (rinv == 0.) {
                // track direction
                tDir << cosLambda * cosPhi0, cosLambda * sinPhi0, sinLambda;
                // distance (of point at dca to reference)
                Vector3d pca(dca * sinPhi0, -dca * cosPhi0, z0);
                dist = pca - refPos;
                // arc-length
                double sArc3D = -dist.dot(nDir) / tDir.dot(nDir);
                sArc2D = sArc3D * cosLambda;
                // position at prediction
                pos = pca + sArc3D * tDir;
                // distance (of point at sArc to reference)
                dist = pos - refPos;
        } else {
                // initial guess of 2D arc-length
                sArc2D = this->getArcLengthXY(refPos(0), refPos(1));
                unsigned int nIter = 0;
                while (nIter < 10) {
                        nIter += 1;
                        // track direction
                        const double dPhi = sArc2D * rinv;
                        const double cosPhi = cos(phi0 + dPhi);
                        const double sinPhi = sin(phi0 + dPhi);
                        tDir << cosLambda * cosPhi, cosLambda * sinPhi, sinLambda;
                        // position at prediction
                        pos << (xRelCenter + sinPhi) / rinv, (yRelCenter - cosPhi) / rinv, z0
                                        + dzds * sArc2D;
                        // distance (of point at sArc to reference)
                        dist = pos - refPos;
                        // arc-length correction (linearizing helix at sArc)
                        const double sCorr3D = -dist.dot(nDir) / tDir.dot(nDir);
                        if (fabs(sCorr3D) > 0.00001) {
                                // iterate
                                sArc2D += sCorr3D * cosLambda;
                        } else {
                                // converged
                                break;
                        }
                }
        }
// projections on measurement directions
        Vector2d pred(dist.dot(uDir), dist.dot(vDir));
        return GblHelixPrediction(sArc2D, pred, tDir, uDir, vDir, nDir, pos);
}
 
 
GblDetectorLayer::GblDetectorLayer(const std::string aName,
                const unsigned int aLayer, const int aDim, const double thickness,
                Eigen::Vector3d& aCenter, Eigen::Vector2d& aResolution,
                Eigen::Vector2d& aPrecision, Eigen::Matrix3d& measTrafo,
                Eigen::Matrix3d& alignTrafo) :
                name(aName), layer(aLayer), measDim(aDim), xbyx0(thickness), center(
                                aCenter), resolution(aResolution), precision(aPrecision), global2meas(
                                measTrafo), global2align(alignTrafo) {
        udir = global2meas.row(0);
        vdir = global2meas.row(1);
        ndir = global2meas.row(2);
}
 
GblDetectorLayer::~GblDetectorLayer() {
}
 
void GblDetectorLayer::print() const {
        IOFormat CleanFmt(4, 0, ", ", "\n", "[", "]");
        std::cout << " Layer " << name << " " << layer << " : " << measDim << "D, "
                        << xbyx0 << " X0, @ " << center.transpose().format(CleanFmt)
                        << ", res " << resolution.transpose().format(CleanFmt) << ", udir "
                        << udir.transpose().format(CleanFmt) << ", vdir "
                        << vdir.transpose().format(CleanFmt) << std::endl;
}
 
unsigned int GblDetectorLayer::getLayerID() const {
        return layer;
}
 
double GblDetectorLayer::getRadiationLength() const {
        return xbyx0;
}
 
Eigen::Vector2d GblDetectorLayer::getResolution() const {
        return resolution;
}
 
Eigen::Vector2d GblDetectorLayer::getPrecision() const {
        return precision;
}
 
Eigen::Vector3d GblDetectorLayer::getCenter() const {
        return center;
}
 
 
Eigen::Matrix3d GblDetectorLayer::getMeasSystemDirs() const {
        return global2meas;;
}
 
 
Eigen::Matrix3d GblDetectorLayer::getAlignSystemDirs() const {
        return global2align;;
}
 
 
GblHelixPrediction GblDetectorLayer::intersectWithHelix(
                GblSimpleHelix hlx) const {
        return hlx.getPrediction(center, udir, vdir);
}
 
 
Matrix<double, 3, 6> GblDetectorLayer::getRigidBodyDerGlobal(
                Eigen::Vector3d& position, Eigen::Vector3d& direction) const {
// lever arms (for rotations)
        Vector3d dist = position;
// dr/dm (residual vs measurement, 1-tdir*ndir^t/tdir*ndir)
        Matrix3d drdm = Matrix3d::Identity()
                        - (direction * ndir.transpose()) / (direction.transpose() * ndir);
// dm/dg (measurement vs 6 rigid body parameters, global system)
        Matrix<double, 3, 6> dmdg = Matrix<double, 3, 6>::Zero();
        dmdg(0, 0) = 1.;
        dmdg(0, 4) = -dist(2);
        dmdg(0, 5) = dist(1);
        dmdg(1, 1) = 1.;
        dmdg(1, 3) = dist(2);
        dmdg(1, 5) = -dist(0);
        dmdg(2, 2) = 1.;
        dmdg(2, 3) = -dist(1);
        dmdg(2, 4) = dist(0);
// drl/dg (local residuals vs rigid body parameters)
        return global2meas * drdm * dmdg;
}
 
 
Matrix<double, 2, 6> GblDetectorLayer::getRigidBodyDerLocal(
                Eigen::Vector3d& position, Eigen::Vector3d& direction) const {
        // track direction in local system
        Vector3d tLoc = global2align * direction;
        // local slopes
        const double uSlope = tLoc[0] / tLoc[2];
        const double vSlope = tLoc[1] / tLoc[2];
        // lever arms (for rotations)
        Vector3d dist = global2align * (position - center);
        const double uPos = dist[0];
        const double vPos = dist[1];
        // wPos = 0 (in detector plane)
        // drl/dg (local residuals (du,dv) vs rigid body parameters)
        Matrix<double, 2, 6> drldg;
        drldg << 1.0, 0.0, -uSlope, vPos * uSlope, -uPos * uSlope, vPos, 0.0, 1.0, -vSlope, vPos
                        * vSlope, -uPos * vSlope, -uPos;
        // local (alignment) to measurement system
        Matrix3d local2meas = global2meas * global2align.transpose();
        return local2meas.block<2, 2>(0, 0) * drldg;
}
 
 
Matrix<double, 6, 6> GblDetectorLayer::getTrafoGlobalToLocal(
                Eigen::Vector3d& offset, Eigen::Matrix3d& rotation) const {
        // transformation global to local
        Matrix<double, 6, 6> glo2loc = Matrix<double, 6, 6>::Zero();
        Matrix3d leverArms;
        leverArms << 0., offset[2], -offset[1], -offset[2], 0., offset[0], offset[1], -offset[0], 0.;
        glo2loc.block<3, 3>(0, 0) = rotation;
        glo2loc.block<3, 3>(0, 3) = -rotation * leverArms;
        glo2loc.block<3, 3>(3, 3) = rotation;
        return glo2loc;
}
 
 
Matrix<double, 6, 6> GblDetectorLayer::getTrafoLocalToGlobal(
                Eigen::Vector3d& offset, Eigen::Matrix3d& rotation) const {
        // transformation local to global
        Matrix<double, 6, 6> loc2glo = Matrix<double, 6, 6>::Zero();
        Matrix3d leverArms;
        leverArms << 0., offset[2], -offset[1], -offset[2], 0., offset[0], offset[1], -offset[0], 0.;
        loc2glo.block<3, 3>(0, 0) = rotation.transpose();
        loc2glo.block<3, 3>(0, 3) = leverArms * rotation.transpose();
        loc2glo.block<3, 3>(3, 3) = rotation.transpose();
        return loc2glo;
}
 
}