Tracking: Implement Brown-Conrady distortion model

Implemented Brown-Conrady lens distortion model with 4 radial and
2 tangential coefficients to improve compatibility with other software,
such as Agisoft Photoscan/Metashapes, 3DF Zephir, RealityCapture,
Bentley ContextCapture, Alisevision Meshroom(opensource).

Also older programs: Bundler, CPMVS.
In general terms, most photogrammetric software.

The new model is available under the distortion model menu in Lens
settings.

For tests and demos check the original patch.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D9037

2 files changed, 30 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/movieclip.c b/source/blender/blenkernel/intern/movieclip.c
index 3ea0f800178..364e6c9bfe4 100644
--- a/source/blender/blenkernel/intern/movieclip.c
+++ b/source/blender/blenkernel/intern/movieclip.c
@@ -687,6 +687,8 @@ typedef struct MovieClipCache {
     float polynomial_k[3];
     float division_k[2];
     float nuke_k[2];
+    float brown_k[4];
+    float brown_p[2];
     short distortion_model;
     bool undistortion_used;
 
@@ -1134,10 +1136,18 @@ static bool check_undistortion_cache_flags(const MovieClip *clip)
   if (!equals_v2v2(&camera->division_k1, cache->postprocessed.division_k)) {
     return false;
   }
+
   if (!equals_v2v2(&camera->nuke_k1, cache->postprocessed.nuke_k)) {
     return false;
   }
 
+  if (!equals_v4v4(&camera->brown_k1, cache->postprocessed.brown_k)) {
+    return false;
+  }
+  if (!equals_v2v2(&camera->brown_p1, cache->postprocessed.brown_p)) {
+    return false;
+  }
+
   return true;
 }
 
@@ -1240,6 +1250,8 @@ static void put_postprocessed_frame_to_cache(
     copy_v3_v3(cache->postprocessed.polynomial_k, &camera->k1);
     copy_v2_v2(cache->postprocessed.division_k, &camera->division_k1);
     copy_v2_v2(cache->postprocessed.nuke_k, &camera->nuke_k1);
+    copy_v4_v4(cache->postprocessed.brown_k, &camera->brown_k1);
+    copy_v2_v2(cache->postprocessed.brown_p, &camera->brown_p1);
     cache->postprocessed.undistortion_used = true;
   }
   else {
diff --git a/source/blender/blenkernel/intern/tracking_util.c b/source/blender/blenkernel/intern/tracking_util.c
index dcaa9082026..bc6c94343b5 100644
--- a/source/blender/blenkernel/intern/tracking_util.c
+++ b/source/blender/blenkernel/intern/tracking_util.c
@@ -457,6 +457,15 @@ static void distortion_model_parameters_from_tracking(
       camera_intrinsics_options->nuke_k1 = camera->nuke_k1;
       camera_intrinsics_options->nuke_k2 = camera->nuke_k2;
       return;
+    case TRACKING_DISTORTION_MODEL_BROWN:
+      camera_intrinsics_options->distortion_model = LIBMV_DISTORTION_MODEL_BROWN;
+      camera_intrinsics_options->brown_k1 = camera->brown_k1;
+      camera_intrinsics_options->brown_k2 = camera->brown_k2;
+      camera_intrinsics_options->brown_k3 = camera->brown_k3;
+      camera_intrinsics_options->brown_k4 = camera->brown_k4;
+      camera_intrinsics_options->brown_p1 = camera->brown_p1;
+      camera_intrinsics_options->brown_p2 = camera->brown_p2;
+      return;
   }
 
   /* Unknown distortion model, which might be due to opening newer file in older Blender.
@@ -491,6 +500,15 @@ static void distortion_model_parameters_from_options(
       camera->nuke_k1 = camera_intrinsics_options->nuke_k1;
       camera->nuke_k2 = camera_intrinsics_options->nuke_k2;
       return;
+    case LIBMV_DISTORTION_MODEL_BROWN:
+      camera->distortion_model = TRACKING_DISTORTION_MODEL_BROWN;
+      camera->brown_k1 = camera_intrinsics_options->brown_k1;
+      camera->brown_k2 = camera_intrinsics_options->brown_k2;
+      camera->brown_k3 = camera_intrinsics_options->brown_k3;
+      camera->brown_k4 = camera_intrinsics_options->brown_k4;
+      camera->brown_p1 = camera_intrinsics_options->brown_p1;
+      camera->brown_p2 = camera_intrinsics_options->brown_p2;
+      return;
   }
 
   /* Libmv returned distortion model which is not known to Blender. This is a logical error in code