CircularAperture.cpp

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/*
 * CircularAperture.cpp
 *
 *  Created on: Oct 08, 2018
 *      Author: Alejandro Alvarez
 */
#include <iostream>
#include "SEFramework/Aperture/CircularAperture.h"
 
namespace SourceXtractor {
 
// enhancing from 5 to 10 smoothens the photometry
const int SUPERSAMPLE_NB = 10;
 
SeFloat CircularAperture::getArea(SeFloat center_x, SeFloat center_y, SeFloat pixel_x, SeFloat pixel_y) const {
  auto dx = pixel_x - center_x;
  auto dy = pixel_y - center_y;
  SeFloat min_supersampled_radius_squared = m_radius > .75 ? (m_radius - .75) * (m_radius - .75) : 0;
  SeFloat max_supersampled_radius_squared = (m_radius + .75) * (m_radius + .75);
 
  auto distance_squared = dx * dx + dy * dy;
  SeFloat area = 0.0;
  if (distance_squared < min_supersampled_radius_squared) {
    area = 1.0;
  }
  else if (distance_squared <= max_supersampled_radius_squared) {
    for (int sub_y = 0; sub_y < SUPERSAMPLE_NB; sub_y++) {
      for (int sub_x = 0; sub_x < SUPERSAMPLE_NB; sub_x++) {
        auto dx2 = dx + SeFloat(sub_x - SUPERSAMPLE_NB / 2) / SUPERSAMPLE_NB;
        auto dy2 = dy + SeFloat(sub_y - SUPERSAMPLE_NB / 2) / SUPERSAMPLE_NB;
        auto supersampled_distance_squared = dx2 * dx2 + dy2 * dy2;
        if (supersampled_distance_squared <= m_radius * m_radius) {
          area += 1.0 / (SUPERSAMPLE_NB * SUPERSAMPLE_NB);
        }
      }
    }
  }
  return area;
}
 
SeFloat CircularAperture::drawArea(SeFloat center_x, SeFloat center_y, SeFloat pixel_x, SeFloat pixel_y) const {
        SeFloat thickness = 0.5;
 
        // define an inner and an outer radius
        SeFloat min_radius_squared = m_radius > thickness ? (m_radius - thickness) * (m_radius - thickness) : 0;
        SeFloat max_radius_squared = (m_radius + thickness) * (m_radius + thickness);
 
        // compare the actual radius against the inner and outer radius
        auto distance_squared = getRadiusSquared(center_x, center_y, pixel_x, pixel_y);
        if (min_radius_squared < distance_squared && distance_squared <= max_radius_squared) {
                return 1.0;
        }
        return 0.0;
}
 
SeFloat CircularAperture::getRadiusSquared(SeFloat center_x, SeFloat center_y, SeFloat pixel_x, SeFloat pixel_y) const {
  auto dist_x = SeFloat(pixel_x) - center_x;
  auto dist_y = SeFloat(pixel_y) - center_y;
 
  return dist_x * dist_x + dist_y * dist_y;
}
 
PixelCoordinate CircularAperture::getMinPixel(SeFloat centroid_x, SeFloat centroid_y) const {
  return PixelCoordinate(centroid_x - m_radius, centroid_y - m_radius);
}
 
PixelCoordinate CircularAperture::getMaxPixel(SeFloat centroid_x, SeFloat centroid_y) const {
  return PixelCoordinate(std::ceil(centroid_x + m_radius), std::ceil(centroid_y + m_radius));
}
 
} // end SourceXtractor