Example usage for org.apache.commons.math3.geometry.euclidean.threed Line revert

Introduction

In this page you can find the example usage for org.apache.commons.math3.geometry.euclidean.threed Line revert.

Prototype

public Line revert() 

Source Link

Document

Get a line with reversed direction.

Usage

From source file:org.orekit.models.earth.Geoid.java

/**
 * {@inheritDoc}//  ww w.j  a v a  2 s.  co m
 *
 * <p> The intersection point is computed using a line search along the
 * specified line. This is accurate when the geoid is slowly varying.
 */
@Override
public GeodeticPoint getIntersectionPoint(final Line lineInFrame, final Vector3D closeInFrame,
        final Frame frame, final AbsoluteDate date) throws OrekitException {
    /*
     * It is assumed that the geoid is slowly varying over it's entire
     * surface. Therefore there will one local intersection.
     */
    // transform to body frame
    final Frame bodyFrame = this.getBodyFrame();
    final Transform frameToBody = frame.getTransformTo(bodyFrame, date);
    final Vector3D close = frameToBody.transformPosition(closeInFrame);
    final Line lineInBodyFrame = frameToBody.transformLine(lineInFrame);

    // set the line's direction so the solved for value is always positive
    final Line line;
    if (lineInBodyFrame.getAbscissa(close) < 0) {
        line = lineInBodyFrame.revert();
    } else {
        line = lineInBodyFrame;
    }

    final ReferenceEllipsoid ellipsoid = this.getEllipsoid();
    // calculate end points
    // distance from line to center of earth, squared
    final double d2 = line.pointAt(0.0).getNormSq();
    // the minimum abscissa, squared
    final double minAbscissa2 = FastMath.pow(ellipsoid.getPolarRadius() + MIN_UNDULATION, 2) - d2;
    // smaller end point of the interval = 0.0 or intersection with
    // min_undulation sphere
    final double lowPoint = FastMath.sqrt(FastMath.max(minAbscissa2, 0.0));
    // the maximum abscissa, squared
    final double maxAbscissa2 = FastMath.pow(ellipsoid.getEquatorialRadius() + MAX_UNDULATION, 2) - d2;
    // larger end point of the interval
    final double highPoint = FastMath.sqrt(maxAbscissa2);

    // line search function
    final UnivariateFunction heightFunction = new UnivariateFunction() {
        @Override
        public double value(final double x) {
            try {
                final GeodeticPoint geodetic = transform(line.pointAt(x), bodyFrame, date);
                return geodetic.getAltitude();
            } catch (OrekitException e) {
                // due to frame transform -> re-throw
                throw new RuntimeException(e);
            }
        }
    };

    // compute answer
    if (maxAbscissa2 < 0) {
        // ray does not pierce bounding sphere -> no possible intersection
        return null;
    }
    // solve line search problem to find the intersection
    final UnivariateSolver solver = new BracketingNthOrderBrentSolver();
    try {
        final double abscissa = solver.solve(MAX_EVALUATIONS, heightFunction, lowPoint, highPoint);
        // return intersection point
        return this.transform(line.pointAt(abscissa), bodyFrame, date);
    } catch (TooManyEvaluationsException e) {
        // no intersection
        return null;
    } catch (MathIllegalArgumentException e) {
        // no intersection
        return null;
    }
}

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