Function MakeGrazingAngleImage

src/colmap/mvs/texture_mapping_test.cc:126–152

Create a camera that views the mesh at a very grazing angle. Camera nearly in-plane with XY mesh, at (0.5, 0.5, 0.01), looking along -Z.

// Create a camera that views the mesh at a very grazing angle.
// Camera nearly in-plane with XY mesh, at (0.5, 0.5, 0.01), looking along -Z.
Image MakeGrazingAngleImage(int width, int height) {
  float K[9] = {0};
  K[0] = static_cast<float>(width);
  K[4] = static_cast<float>(height);
  K[2] = static_cast<float>(width) / 2.0f;
  K[5] = static_cast<float>(height) / 2.0f;
  K[8] = 1.0f;

  // R: 180° around X.
  float R[9] = {1, 0, 0, 0, -1, 0, 0, 0, -1};

  // C = (0.5, 0.5, 0.01), T = -R*C = [-0.5, 0.5, 0.01]
  float T[3] = {-0.5f, 0.5f, 0.01f};

  Image image("grazing.png",
              static_cast<size_t>(width),
              static_cast<size_t>(height),
              K,
              R,
              T);

  Bitmap bitmap(width, height, /*as_rgb=*/true);
  bitmap.Fill(BitmapColor<uint8_t>(128));
  image.SetBitmap(std::move(bitmap));

  return image;
}

// Create a 4-face pyramid mesh.
PlyMesh MakePyramidMesh() {