Initial commit: scene-actor-extraction pipeline

Source (KPN++ pipeline nodes, ArcFace embedders, SCRFD/YuNet detectors,
gallery builder), build scripts, and eval artifacts.

- external/KPN as a git submodule (gitea.tourolle.paris/dtourolle/KPN)
- ONNX models tracked via Git LFS (models/*.onnx)
- generated outputs, TensorRT engines, reference repos, and media ignored

src/build_gallery.cpp

@@ -0,0 +1,85 @@
+// build_gallery — build an actor embedding gallery from a directory of images
+//
+// Gallery directory layout:
+//   gallery_root/
+//     nm0000093_Brad_Pitt/
+//       img1.jpg
+//       img2.jpg
+//     nm0000129_Cate_Blanchett/
+//       ...
+//
+// Usage:
+//   build_gallery --root <gallery_root> --output <gallery.json> [options]
+//
+// Options:
+//   --detector <path>   SCRFD detector model (default: models/scrfd_500m_bnkps.onnx)
+//   --arcface <path>    ArcFace model (default: models/arcface_w600k_r50.onnx)
+//   --conf <f>          face detection confidence threshold (default: 0.5)
+//   --nms <f>           NMS IoU threshold (default: 0.4)
+
+#include "gallery/gallery_builder.hpp"
+#include "gallery/gallery_store.hpp"
+#include "config.hpp"
+
+#include <cstring>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+int main(int argc, char** argv) {
+    std::string root_path, output_path;
+    std::string detector_model = kDefaultDetectorModel;
+    std::string arcface_model  = kDefaultArcfaceModel;
+    float conf = 0.5f, nms_thr = 0.4f;
+    int   max_side = 500;
+
+    for (int i = 1; i < argc; ++i) {
+        auto arg  = [&](const char* f) { return std::strcmp(argv[i], f) == 0; };
+        auto next = [&]() -> std::string {
+            if (++i >= argc)
+                throw std::runtime_error(std::string("missing arg after ") + argv[i-1]);
+            return argv[i];
+        };
+        try {
+            if      (arg("--root"))      root_path      = next();
+            else if (arg("--output"))    output_path    = next();
+            else if (arg("--detector"))  detector_model = next();
+            else if (arg("--arcface"))   arcface_model  = next();
+            else if (arg("--conf"))      conf           = std::stof(next());
+            else if (arg("--nms"))       nms_thr        = std::stof(next());
+            else if (arg("--max-side"))  max_side       = std::stoi(next());
+            else { std::cerr << "[warn] unknown flag: " << argv[i] << "\n"; }
+        } catch (const std::exception& e) {
+            std::cerr << "Error: " << e.what() << "\n";
+            return 1;
+        }
+    }
+
+    if (root_path.empty() || output_path.empty()) {
+        std::cerr << "Usage: build_gallery --root <dir> --output <gallery.json> "
+                     "[--detector <path>] [--arcface <path>] [--max-side <N>]\n";
+        return 1;
+    }
+
+    BuildConfig cfg;
+    cfg.gallery_root   = root_path;
+    cfg.detector_model = detector_model;
+    cfg.arcface_model  = arcface_model;
+    cfg.detector_conf  = conf;
+    cfg.detector_nms   = nms_thr;
+    cfg.max_side       = max_side;
+
+    try {
+        ActorGallery gallery = build_gallery(cfg);
+        if (gallery.actors.empty()) {
+            std::cerr << "No actors built — check your gallery directory.\n";
+            return 1;
+        }
+        save_gallery(output_path, gallery);
+        std::cerr << "Gallery saved to: " << output_path << "\n";
+    } catch (const std::exception& e) {
+        std::cerr << "Fatal: " << e.what() << "\n";
+        return 1;
+    }
+    return 0;
+}