bool Interpolator2D::CalculateWeights ( )

inlineprivate

Calculate the weights corresponding to the points in the output grid. Weights are calculated by bi-linear interpolation. For interpolation, the triangle which contains the point and has the smallest radius is searched. If this is not available in case of extrapolation, the condition is relaxed and requires only the circle to contain the point. If such circle is not available, the circle with the closest center is chosen.

Definition at line 172 of file Interpolator2D.h.

References Interpolator2D::weight::c, Interpolator2D::weight::w, Interpolator2D::vec::x, and Interpolator2D::vec::y.

Referenced by SetOutputGrid().

    {
        weights.reserve(outputGrid.size());

        // Loop over all points in the output grid
        for (auto ip=outputGrid.cbegin(); ip<outputGrid.cend(); ip++)
        {
            double mindd = DBL_MAX;

            auto mint = circles.cend();
            auto minc = circles.cend();
            auto mind = circles.cend();

            for (auto ic=circles.cbegin(); ic<circles.cend(); ic++)
            {
                // Check if point is inside the triangle
                if (ic->isInsideTriangle(*ip))
                {
                    if (mint==circles.cend() || ic->r<mint->r)
                        mint = ic;
                }

                // If we have found such a triangle, no need to check for more
                if (mint!=circles.cend())
                    continue;

                // maybe at least inside the circle
                const double dd = ic->dist(*ip);
                if (dd<ic->r)
                {
                    if (minc==circles.cend() || ic->r<minc->r)
                        minc = ic;
                }

                // If we found such a circle, no need to check for more
                if (minc!=circles.cend())
                    continue;

                // then look for the closest circle center
                if (dd<mindd)
                {
                    mindd = dd;
                    mind  = ic;
                }
            }

            // Choose the best of the three options
            const auto it = mint==circles.cend() ? (minc==circles.cend() ? mind : minc) : mint;
            if (it==circles.cend())
                return false;

            // Calculate the bi-linear interpolation
            const vec &p1 = it->p[0];
            const vec &p2 = it->p[1];
            const vec &p3 = it->p[2];

            const double dy23 = p2.y - p3.y;
            const double dy31 = p3.y - p1.y;
            const double dy12 = p1.y - p2.y;

            const double dx32 = p3.x - p2.x;
            const double dx13 = p1.x - p3.x;
            const double dx21 = p2.x - p1.x;

            const double dxy23 = p2^p3;
            const double dxy31 = p3^p1;
            const double dxy12 = p1^p2;

            const double det = dxy12 + dxy23 + dxy31;

            const double w1 = (dy23*ip->x + dx32*ip->y + dxy23)/det;
            const double w2 = (dy31*ip->x + dx13*ip->y + dxy31)/det;
            const double w3 = (dy12*ip->x + dx21*ip->y + dxy12)/det;

            // Store the original grid-point, the circle's parameters
            // and the calculate weights
            weight w;
            w.x = ip->x;
            w.y = ip->y;
            w.c = *it;
            w.w[0] = w1;
            w.w[1] = w2;
            w.w[2] = w3;

            weights.push_back(w);
        }

        return true;
    }

Here is the caller graph for this function: