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Create process_image.cpp
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process_image.cpp
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process_image.cpp
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// process_image.cpp
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#include <pybind11/pybind11.h>
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#include <pybind11/numpy.h>
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#include <pybind11/stl.h>
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#include <cmath>
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#include <vector>
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#include <array>
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#include <algorithm>
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#include <limits>
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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namespace py = pybind11;
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/**
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* Compute the intersection of a ray with an axis-aligned bounding box (AABB).
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*
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* This function determines where a ray enters and exits the AABB defined by box_min and box_max.
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* If the ray does not intersect the box, it returns false.
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*/
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bool ray_aabb_intersection(
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const std::array<double, 3>& ray_origin,
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const std::array<double, 3>& ray_direction,
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const std::array<double, 3>& box_min,
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const std::array<double, 3>& box_max,
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double& t_entry,
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double& t_exit)
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{
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double tmin = -std::numeric_limits<double>::infinity();
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double tmax = std::numeric_limits<double>::infinity();
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for (int i = 0; i < 3; ++i)
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{
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if (std::abs(ray_direction[i]) > 1e-8)
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{
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double t1 = (box_min[i] - ray_origin[i]) / ray_direction[i];
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double t2 = (box_max[i] - ray_origin[i]) / ray_direction[i];
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if (t1 > t2) std::swap(t1, t2);
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tmin = std::max(tmin, t1);
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tmax = std::min(tmax, t2);
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if (tmin > tmax)
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return false;
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}
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else
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{
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// Ray is parallel to the slab. If the origin is not within the slab, no intersection
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if (ray_origin[i] < box_min[i] || ray_origin[i] > box_max[i])
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return false;
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}
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}
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t_entry = tmin;
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t_exit = tmax;
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return true;
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}
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/**
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* Convert a 3D point to voxel indices within the voxel grid.
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*
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* Given a point in space and the voxel grid extents, compute which voxel it falls into.
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*/
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std::tuple<pybind11::ssize_t, pybind11::ssize_t, pybind11::ssize_t> point_to_voxel_indices(
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const std::array<double, 3>& point,
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const std::vector<std::pair<double, double>>& voxel_grid_extent,
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const std::array<pybind11::ssize_t, 3>& voxel_grid_size)
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{
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double x_min = voxel_grid_extent[0].first;
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double x_max = voxel_grid_extent[0].second;
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double y_min = voxel_grid_extent[1].first;
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double y_max = voxel_grid_extent[1].second;
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double z_min = voxel_grid_extent[2].first;
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double z_max = voxel_grid_extent[2].second;
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double x = point[0];
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double y = point[1];
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double z = point[2];
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// Check if the point is inside the voxel grid bounds
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if (x_min <= x && x <= x_max && y_min <= y && y <= y_max && z_min <= z && z <= z_max)
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{
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pybind11::ssize_t nx = voxel_grid_size[0];
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pybind11::ssize_t ny = voxel_grid_size[1];
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pybind11::ssize_t nz = voxel_grid_size[2];
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// Compute normalized position within the grid
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double x_norm = (x - x_min) / (x_max - x_min);
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double y_norm = (y - y_min) / (y_max - y_min);
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double z_norm = (z - z_min) / (z_max - z_min);
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// Convert normalized coordinates to voxel indices
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pybind11::ssize_t x_idx = static_cast<pybind11::ssize_t>(x_norm * nx);
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pybind11::ssize_t y_idx = static_cast<pybind11::ssize_t>(y_norm * ny);
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pybind11::ssize_t z_idx = static_cast<pybind11::ssize_t>(z_norm * nz);
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// Clamp the indices to valid range
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x_idx = std::min(std::max(x_idx, pybind11::ssize_t(0)), nx - 1);
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y_idx = std::min(std::max(y_idx, pybind11::ssize_t(0)), ny - 1);
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z_idx = std::min(std::max(z_idx, pybind11::ssize_t(0)), nz - 1);
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return std::make_tuple(x_idx, y_idx, z_idx);
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}
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else
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{
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// The point is outside the voxel grid
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return std::make_tuple(-1, -1, -1);
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}
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}
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/**
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* Process an image and update the voxel grid and celestial sphere texture.
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*
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* This function:
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* 1. Computes the direction of each pixel in the image.
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* 2. Maps that direction to RA/Dec to find the corresponding brightness on the celestial sphere.
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* 3. Optionally subtracts the background (celestial sphere brightness) from the image brightness.
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* 4. If updating the celestial sphere, accumulates brightness values into the celestial_sphere_texture.
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* 5. If a voxel grid is provided, casts rays into the grid and updates voxel brightness accordingly.
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*/
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void process_image_cpp(
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py::array_t<double> image,
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std::array<double, 3> earth_position,
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std::array<double, 3> pointing_direction,
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double fov,
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pybind11::ssize_t image_width,
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pybind11::ssize_t image_height,
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py::array_t<double> voxel_grid,
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std::vector<std::pair<double, double>> voxel_grid_extent,
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double max_distance,
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int num_steps,
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py::array_t<double> celestial_sphere_texture,
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double center_ra_rad,
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double center_dec_rad,
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double angular_width_rad,
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double angular_height_rad,
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bool update_celestial_sphere,
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bool perform_background_subtraction
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)
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{
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// Access the image and celestial sphere texture arrays
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auto image_unchecked = image.unchecked<2>();
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auto texture_mutable = celestial_sphere_texture.mutable_unchecked<2>();
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pybind11::ssize_t texture_height = celestial_sphere_texture.shape(0);
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pybind11::ssize_t texture_width = celestial_sphere_texture.shape(1);
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// Check if voxel_grid is provided and non-empty
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bool voxel_grid_provided = voxel_grid && voxel_grid.size() > 0;
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// Variables for voxel grid (only if voxel_grid_provided)
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std::array<pybind11::ssize_t, 3> voxel_grid_size = {0, 0, 0};
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double x_min = 0, x_max = 0;
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double y_min = 0, y_max = 0;
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double z_min = 0, z_max = 0;
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// We only declare voxel_grid_mutable inside the if block if voxel_grid is provided
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// This avoids the need for a default constructor for unchecked_mutable_reference.
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py::detail::unchecked_mutable_reference<double, 3>* voxel_grid_mutable_ptr = nullptr;
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if (voxel_grid_provided)
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{
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// Get a mutable reference to the voxel grid
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auto voxel_grid_mutable = voxel_grid.mutable_unchecked<3>();
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voxel_grid_mutable_ptr = &voxel_grid_mutable;
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// Extract voxel grid dimensions and extents
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voxel_grid_size = {
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voxel_grid.shape(0),
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voxel_grid.shape(1),
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voxel_grid.shape(2)
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};
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x_min = voxel_grid_extent[0].first;
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x_max = voxel_grid_extent[0].second;
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y_min = voxel_grid_extent[1].first;
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y_max = voxel_grid_extent[1].second;
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z_min = voxel_grid_extent[2].first;
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z_max = voxel_grid_extent[2].second;
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}
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// Compute focal length from the field of view
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double focal_length = (image_width / 2.0) / std::tan(fov / 2.0);
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// Principal point (optical center)
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double cx = image_width / 2.0;
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double cy = image_height / 2.0;
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// pointing_direction is the z-axis of the camera frame
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// Normalize pointing_direction to ensure it's a unit vector
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double z_norm = std::sqrt(pointing_direction[0]*pointing_direction[0] +
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pointing_direction[1]*pointing_direction[1] +
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pointing_direction[2]*pointing_direction[2]);
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pointing_direction[0] /= z_norm;
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pointing_direction[1] /= z_norm;
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pointing_direction[2] /= z_norm;
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// Define an 'up' vector to avoid singularities
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std::array<double, 3> up = {0.0, 0.0, 1.0};
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if ((std::abs(pointing_direction[0] - up[0]) < 1e-8 &&
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std::abs(pointing_direction[1] - up[1]) < 1e-8 &&
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std::abs(pointing_direction[2] - up[2]) < 1e-8) ||
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(std::abs(pointing_direction[0] + up[0]) < 1e-8 &&
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std::abs(pointing_direction[1] + up[1]) < 1e-8 &&
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std::abs(pointing_direction[2] + up[2]) < 1e-8))
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{
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up = {0.0, 1.0, 0.0};
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}
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// Compute orthonormal basis: x_axis, y_axis, z_axis (z_axis = pointing_direction)
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std::array<double, 3> z_axis = pointing_direction;
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std::array<double, 3> x_axis;
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x_axis[0] = up[1]*z_axis[2] - up[2]*z_axis[1];
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x_axis[1] = up[2]*z_axis[0] - up[0]*z_axis[2];
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x_axis[2] = up[0]*z_axis[1] - up[1]*z_axis[0];
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double x_norm = std::sqrt(x_axis[0]*x_axis[0] + x_axis[1]*x_axis[1] + x_axis[2]*x_axis[2]);
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x_axis[0] /= x_norm;
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x_axis[1] /= x_norm;
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x_axis[2] /= x_norm;
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std::array<double, 3> y_axis;
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y_axis[0] = z_axis[1]*x_axis[2] - z_axis[2]*x_axis[1];
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y_axis[1] = z_axis[2]*x_axis[0] - z_axis[0]*x_axis[2];
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y_axis[2] = z_axis[0]*x_axis[1] - z_axis[1]*x_axis[0];
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// Iterate over each pixel in the image
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#pragma omp parallel for
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for (pybind11::ssize_t i = 0; i < image_height; ++i)
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{
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for (pybind11::ssize_t j = 0; j < image_width; ++j)
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{
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double brightness = image_unchecked(i, j);
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if (brightness > 0)
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{
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// Compute the direction in camera coordinates
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double x_cam = (j - cx);
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double y_cam = (i - cy);
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double z_cam = focal_length;
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double norm = std::sqrt(x_cam*x_cam + y_cam*y_cam + z_cam*z_cam);
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double direction_camera[3] = { x_cam/norm, y_cam/norm, z_cam/norm };
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// Transform direction_camera to world coordinates
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double direction_world[3];
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direction_world[0] = x_axis[0]*direction_camera[0] + y_axis[0]*direction_camera[1] + z_axis[0]*direction_camera[2];
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direction_world[1] = x_axis[1]*direction_camera[0] + y_axis[1]*direction_camera[1] + z_axis[1]*direction_camera[2];
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direction_world[2] = x_axis[2]*direction_camera[0] + y_axis[2]*direction_camera[1] + z_axis[2]*direction_camera[2];
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// Normalize direction_world (should already be unit, but just in case)
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double dir_norm = std::sqrt(direction_world[0]*direction_world[0] +
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direction_world[1]*direction_world[1] +
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direction_world[2]*direction_world[2]);
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direction_world[0] /= dir_norm;
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direction_world[1] /= dir_norm;
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direction_world[2] /= dir_norm;
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// Compute RA/Dec for direction_world
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double dx = direction_world[0];
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double dy = direction_world[1];
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double dz = direction_world[2];
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double r = std::sqrt(dx*dx + dy*dy + dz*dz);
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double dec = std::asin(dz / r);
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double ra = std::atan2(dy, dx);
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if (ra < 0) ra += 2 * M_PI;
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// Compute offsets from the center of the sky patch
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double ra_offset = ra - center_ra_rad;
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double dec_offset = dec - center_dec_rad;
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// Adjust RA offset for wrapping
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if (ra_offset > M_PI) ra_offset -= 2 * M_PI;
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if (ra_offset < -M_PI) ra_offset += 2 * M_PI;
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// Check if within the defined sky patch
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bool within_sky_patch = (std::abs(ra_offset) <= angular_width_rad / 2) &&
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(std::abs(dec_offset) <= angular_height_rad / 2);
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// Map RA/Dec to texture coordinates
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double u = (ra_offset + angular_width_rad / 2) / angular_width_rad * texture_width;
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double v = (dec_offset + angular_height_rad / 2) / angular_height_rad * texture_height;
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pybind11::ssize_t u_idx = static_cast<pybind11::ssize_t>(u);
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pybind11::ssize_t v_idx = static_cast<pybind11::ssize_t>(v);
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// Clamp texture coordinates
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u_idx = std::min(std::max(u_idx, pybind11::ssize_t(0)), texture_width - 1);
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v_idx = std::min(std::max(v_idx, pybind11::ssize_t(0)), texture_height - 1);
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// Background subtraction
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double background_brightness = 0.0;
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if (within_sky_patch)
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{
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background_brightness = texture_mutable(v_idx, u_idx);
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}
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if (perform_background_subtraction)
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{
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brightness -= background_brightness;
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if (brightness <= 0)
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continue; // Skip if adjusted brightness is zero or negative
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}
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// Update celestial sphere texture if needed
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if (update_celestial_sphere && within_sky_patch)
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{
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#pragma omp atomic
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texture_mutable(v_idx, u_idx) += brightness;
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}
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// If we have a voxel grid, cast rays into it and update voxel brightness
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if (voxel_grid_provided)
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{
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// Safe to use voxel_grid_mutable_ptr now because voxel_grid_provided is true
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auto &voxel_grid_mutable = *voxel_grid_mutable_ptr; // Reference to the voxel grid
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// Ray casting into voxel grid
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double step_size = max_distance / num_steps;
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std::array<double, 3> ray_origin = { earth_position[0], earth_position[1], earth_position[2] };
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std::array<double, 3> ray_direction = { direction_world[0], direction_world[1], direction_world[2] };
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std::array<double, 3> box_min = { x_min, y_min, z_min };
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std::array<double, 3> box_max = { x_max, y_max, z_max };
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double t_entry, t_exit;
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if (ray_aabb_intersection(ray_origin, ray_direction, box_min, box_max, t_entry, t_exit))
|
||||||
|
{
|
||||||
|
t_entry = std::max(t_entry, 0.0);
|
||||||
|
t_exit = std::min(t_exit, max_distance);
|
||||||
|
|
||||||
|
if (t_entry <= t_exit)
|
||||||
|
{
|
||||||
|
int s_entry = static_cast<int>(t_entry / step_size);
|
||||||
|
int s_exit = static_cast<int>(t_exit / step_size);
|
||||||
|
|
||||||
|
for (int s = s_entry; s <= s_exit; ++s)
|
||||||
|
{
|
||||||
|
double d = s * step_size;
|
||||||
|
double px = ray_origin[0] + d * ray_direction[0];
|
||||||
|
double py = ray_origin[1] + d * ray_direction[1];
|
||||||
|
double pz = ray_origin[2] + d * ray_direction[2];
|
||||||
|
|
||||||
|
auto indices = point_to_voxel_indices({ px, py, pz }, voxel_grid_extent, voxel_grid_size);
|
||||||
|
pybind11::ssize_t x_idx = std::get<0>(indices);
|
||||||
|
pybind11::ssize_t y_idx = std::get<1>(indices);
|
||||||
|
pybind11::ssize_t z_idx = std::get<2>(indices);
|
||||||
|
|
||||||
|
if (x_idx >= 0)
|
||||||
|
{
|
||||||
|
#pragma omp atomic
|
||||||
|
voxel_grid_mutable(x_idx, y_idx, z_idx) += brightness;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
// Expose the function to Python
|
||||||
|
PYBIND11_MODULE(process_image_cpp, m) {
|
||||||
|
m.doc() = "C++ implementation of the process_image function";
|
||||||
|
m.def("process_image_cpp", &process_image_cpp, "Process image and update voxel grid in C++",
|
||||||
|
py::arg("image"),
|
||||||
|
py::arg("earth_position"),
|
||||||
|
py::arg("pointing_direction"),
|
||||||
|
py::arg("fov"),
|
||||||
|
py::arg("image_width"),
|
||||||
|
py::arg("image_height"),
|
||||||
|
py::arg("voxel_grid"),
|
||||||
|
py::arg("voxel_grid_extent"),
|
||||||
|
py::arg("max_distance"),
|
||||||
|
py::arg("num_steps"),
|
||||||
|
py::arg("celestial_sphere_texture"),
|
||||||
|
py::arg("center_ra_rad"),
|
||||||
|
py::arg("center_dec_rad"),
|
||||||
|
py::arg("angular_width_rad"),
|
||||||
|
py::arg("angular_height_rad"),
|
||||||
|
py::arg("update_celestial_sphere"),
|
||||||
|
py::arg("perform_background_subtraction")
|
||||||
|
);
|
||||||
|
}
|
||||||
Loading…
Add table
Add a link
Reference in a new issue