SearchTable.icc

#if !defined(ISCE_UNWRAP_ICU_SEARCHTABLE_ICC)
#error "SearchTable.icc is an implementation detail of class SearchTable."
#endif
 
namespace isce3::unwrap::icu
{
 
inline
SearchTable::SearchTable(
    const int maxdist, 
    const float ratioDxDy)
{
    // Width of square bounding circle with max radius
    const int w = 2 * maxdist + 1;
 
    _searchpts = new offset2_t[w*w];
    _npts = new size_t[maxdist+1];
 
    // Get ratio squared (must be >1).
    float ratioSqx, ratioSqy;
    if (ratioDxDy > 1.f)
    {
        ratioSqx = ratioDxDy * ratioDxDy;
        ratioSqy = 1.f;
    }
    else
    {
        ratioSqx = 1.f;
        ratioSqy = 1.f / (ratioDxDy * ratioDxDy);
    }
 
    // Calculate squared distance to each point within the square. Distance 
    // contours are elliptical depending on the relative pixel spacing in x & y.
    auto distSq = new float[w*w];
    for (int y = -maxdist; y <= maxdist; ++y)
    {
        for (int x = -maxdist; x <= maxdist; ++x)
        {
            size_t i = (y + maxdist) * w + (x + maxdist);
            distSq[i] = ratioSqy * float(y*y) + ratioSqx * float(x*x);
        }
    }
 
    // Init mask of visited points (all unvisited except center pixel).
    auto visited = new bool[w*w];
    for (size_t i = 0; i < w*w; ++i) { visited[i] = false; }
    visited[maxdist * w + maxdist] = true;
 
    // Populate the search table by finding points within the annulus of each 
    // successive search radius.
    _npts[0] = 0;
    size_t n = 0;
    for (int d = 1; d <= maxdist; ++d)
    {
        float dSq = float(d*d);
 
        for (int y = -d; y <= d; ++y)
        {
            for (int x = -d; x <= d; ++x)
            {
                size_t i = (y + maxdist) * w + (x + maxdist);
                if (distSq[i] <= dSq && !visited[i])
                {
                    _searchpts[n] = {x, y};
                    visited[i] = true;
                    ++n;
                }
            }
        }
 
        _npts[d] = n;
    }
 
    delete[] distSq;
    delete[] visited;
}
 
inline
SearchTable::~SearchTable()
{
    delete[] _searchpts;
    delete[] _npts;
}
 
inline
offset2_t & SearchTable::operator[](
    const size_t pos) const
{
    return _searchpts[pos];
}
 
inline
size_t SearchTable::numPtsInEllipse(
    const int a) const
{
    return _npts[a];
}
 
}