Recalibrate default test catalog exposure

README.md

@@ -47,10 +47,10 @@ This writes `minkowski_accel_000000.png` through
 input; the acceleration generator is only a reproducible flat-spacetime test
 fixture.  The current movie path still renders frames independently while the
 time-slab/RayPool scheduler is implemented next, so it must not yet be used
-as a performance measurement for numerical-relativity data.  Movie mode uses
-the same `1e-5` exposure by default when `--exposure` is omitted; this differs
-from the legacy single-frame default so the accelerated test catalog does not
-clip to white.
+as a performance measurement for numerical-relativity data.  The current
+synthetic test catalog uses global default exposure `1e-3`; the accelerated
+benchmark explicitly uses `1e-5` because its physical Doppler blue shift
+otherwise clips the later frames.
 
 PNG output is optional so the default build has no `libpng` dependency. Build
 with `make ENABLE_PNG=1`, then select it with a `.png` output path:
@@ -136,9 +136,10 @@ production refinement threshold.
 `--look-ra-deg` and `--look-dec-deg` rotate that fixed tetrad so its forward
 axis is the corresponding catalog direction; their defaults reproduce the
 original `-Z` view. `--exposure` converts a catalog's physical flux
-normalization to the prototype HDR scale. Its default preserves the synthetic
-catalog benchmark; a 2MASS blackbody normalization in steradians requires a
-much larger display exposure such as the example above. The optics path
+normalization to the prototype HDR scale. The current synthetic catalog is
+calibrated for default exposure `1e-3`; a 2MASS blackbody normalization in
+steradians requires a much larger display exposure such as the example above.
+The optics path
 integrates each fitted Planck spectrum through CIE 1931 color-matching functions
 and converts the resulting radiance to linear sRGB; it does not use an empirical
 color-temperature RGB approximation.

src/main.c

@@ -17,7 +17,6 @@ typedef struct {
   int width, height;
   int coarse_cell_pixels;
   int draw_mesh;
-  int exposure_was_set;
   double horizontal_fov_deg, look_ra_deg, look_dec_deg, exposure;
   double observer_inward_speed;
   PointSpreadFunction psf;
@@ -98,7 +97,7 @@ static int parse_args(int argc, char **argv, Settings *s,
                   .horizontal_fov_deg = 30.0,
                   .look_ra_deg = 270.0,
                   .look_dec_deg = 0.0,
-                  .exposure = 100.0,
+                  .exposure = 1e-3,
                   .psf = {2.7, 4.5},
                   .catalog_path = "assets/sky_grid_5deg.csv",
                   .output_path = "output/imgs/minkowski_sky.ppm",
@@ -128,7 +127,6 @@ static int parse_args(int argc, char **argv, Settings *s,
                !parse_dec_deg(argv[++i], &s->look_dec_deg)) {
     } else if (!strcmp(argv[i], "--exposure") && i + 1 < argc &&
                !parse_positive(argv[++i], &s->exposure)) {
-      s->exposure_was_set = 1;
     } else if (!strcmp(argv[i], "--observer-inward-speed") && i + 1 < argc &&
                !parse_speed(argv[++i], &s->observer_inward_speed)) {
     } else if (!strcmp(argv[i], "--psf-fwhm-pixels") && i + 1 < argc &&
@@ -235,14 +233,7 @@ static int render_movie(const Settings *s, const StarCatalog *catalog,
                         const SpacetimeSource *spacetime) {
   ObserverTrack track = {0};
   Movie movie = {0};
-  Settings frame_settings = *s;
   int result = -1;
-  /* The single-image sky fixture historically used an exposure intended for
-   * static inspection.  A near-light-speed movie makes it clip immediately;
-   * retain that single-frame default but choose a legible, fixed test exposure
-   * for sequences unless the caller explicitly supplied --exposure. */
-  if (!frame_settings.exposure_was_set)
-    frame_settings.exposure = 1e-5;
   if (s->observer_track_path == NULL ||
       observer_track_load_csv(&track, s->observer_track_path) ||
       movie_init(&movie, &track, s->movie_start_time, s->movie_duration,
@@ -251,8 +242,8 @@ static int render_movie(const Settings *s, const StarCatalog *catalog,
   for (size_t i = 0; i < movie.frame_count; ++i) {
     char output_path[PATH_MAX];
     if (frame_output_path(output_path, s, movie.frames[i].frame_id) ||
-        render_observer_frame(&frame_settings, catalog, spacetime,
-                              &movie.frames[i].observer, output_path))
+        render_observer_frame(s, catalog, spacetime, &movie.frames[i].observer,
+                              output_path))
       goto done;
   }
   result = 0;

tests/test_frame.c

@@ -9,6 +9,7 @@
 
 int main(void) {
   const int width = 100, height = 100;
+  const double test_exposure = 1e-3;
   const PointSpreadFunction psf = {.fwhm_pixels = 2.7, .moffat_beta = 4.5};
   const GeodesicTraceConfig trace = {.coordinate_time_step = 0.25,
                                      .max_steps = 100};
@@ -25,7 +26,8 @@ int main(void) {
       frame_lens_mesh_trace(&mesh, &spacetime, &observer, &trace))
     goto done;
   const size_t images =
-      frame_splat_catalog(&mesh, &catalog, hdr, width, height, 100.0, &psf);
+      frame_splat_catalog(&mesh, &catalog, hdr, width, height, test_exposure,
+                          &psf);
   if (images != 1 || hdr[3 * (50 * width + 50)] <= 0.0) {
     fputs("flat-space inverse lens-map regression failed\n", stderr);
     goto done;
@@ -42,10 +44,10 @@ int main(void) {
   omp_set_dynamic(0);
   omp_set_num_threads(1);
   const size_t serial_images = frame_splat_catalog(
-      &mesh, &catalog, serial_hdr, width, height, 100.0, &psf);
+      &mesh, &catalog, serial_hdr, width, height, test_exposure, &psf);
   omp_set_num_threads(4);
   const size_t parallel_images = frame_splat_catalog(
-      &mesh, &catalog, parallel_hdr, width, height, 100.0, &psf);
+      &mesh, &catalog, parallel_hdr, width, height, test_exposure, &psf);
   omp_set_num_threads(original_threads);
   for (int value = 0; value < width * height * 3; ++value)
     if (fabs(serial_hdr[value] - parallel_hdr[value]) >
@@ -100,7 +102,7 @@ int main(void) {
   if (frame_lens_mesh_build_coarse(&fine_mesh, width, height, 1, 0.1) ||
       frame_lens_mesh_trace(&fine_mesh, &spacetime, &observer, &trace) ||
       frame_splat_catalog(&fine_mesh, &fine_catalog, hdr, width, height,
-                          100.0, &psf) != 1) {
+                          test_exposure, &psf) != 1) {
     fputs("fine source-triangle containment regression failed\n", stderr);
     frame_lens_mesh_destroy(&fine_mesh);
     goto done;