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/gallery/gallery_builder.cpp

@@ -0,0 +1,115 @@
+#include "gallery_builder.hpp"
+#include "arcface_embedder.hpp"
+#include "face_utils.hpp"
+#include "ort_provider.hpp"
+#include "scrfd_decoder.hpp"
+
+#include <opencv2/imgcodecs.hpp>
+
+#include <algorithm>
+#include <filesystem>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+namespace fs = std::filesystem;
+
+// ── Parse "nm0000093_Brad_Pitt" → ("nm0000093", "Brad Pitt") ─────────────────
+static std::pair<std::string, std::string> parse_dir_name(const std::string& dirname) {
+    auto pos = dirname.find('_');
+    if (pos == std::string::npos) return {dirname, dirname};
+
+    std::string imdb_id = dirname.substr(0, pos);
+    std::string raw     = dirname.substr(pos + 1);
+    std::string name;
+    name.reserve(raw.size());
+    for (char c : raw)
+        name += (c == '_' ? ' ' : c);
+    return {imdb_id, name};
+}
+
+// ── Public API ────────────────────────────────────────────────────────────────
+
+ActorGallery build_gallery(const BuildConfig& cfg) {
+    const OrtProvider provider = detect_ort_provider();
+    std::cerr << "[build_gallery] inference provider: " << provider_name(provider) << "\n";
+
+    SCRFDDecoder    decoder(cfg.detector_model, cfg.detector_conf, cfg.detector_nms, provider);
+    ArcFaceEmbedder arcface(cfg.arcface_model, provider);
+
+    ActorGallery gallery;
+
+    for (const auto& actor_dir : fs::directory_iterator(cfg.gallery_root)) {
+        if (!actor_dir.is_directory()) continue;
+
+        auto [imdb_id, name] = parse_dir_name(actor_dir.path().filename().string());
+        std::cerr << "[build_gallery] " << name << " (" << imdb_id << ")\n";
+
+        ActorGallery::Actor actor;
+        actor.imdb_id = imdb_id;
+        actor.name    = name;
+
+        static const std::vector<std::string> kExts{".jpg", ".jpeg", ".png", ".webp"};
+        for (const auto& img_file : fs::directory_iterator(actor_dir.path())) {
+            if (!img_file.is_regular_file()) continue;
+            std::string ext = img_file.path().extension().string();
+            std::transform(ext.begin(), ext.end(), ext.begin(), ::tolower);
+            if (std::find(kExts.begin(), kExts.end(), ext) == kExts.end()) continue;
+
+            cv::Mat img = cv::imread(img_file.path().string());
+            if (img.empty()) {
+                std::cerr << "  [skip] cannot read " << img_file.path().filename() << "\n";
+                continue;
+            }
+
+            if (cfg.max_side > 0) {
+                const int big = std::max(img.cols, img.rows);
+                if (big > cfg.max_side) {
+                    const double s = static_cast<double>(cfg.max_side) / big;
+                    cv::resize(img, img, {}, s, s, cv::INTER_AREA);
+                }
+            }
+
+            auto faces = decoder.detect(img);
+
+            if (faces.empty()) {
+                std::cerr << "  [skip] no face: " << img_file.path().filename() << "\n";
+                continue;
+            }
+            if (faces.size() > 1) {
+                std::cerr << "  [warn] " << faces.size() << " faces, using highest confidence: "
+                          << img_file.path().filename() << "\n";
+            }
+
+            const auto& best = *std::max_element(
+                faces.begin(), faces.end(),
+                [](const DetectedFace& a, const DetectedFace& b) {
+                    return a.confidence < b.confidence;
+                });
+
+            cv::Mat crop = align_face(img, best.landmarks);
+            if (crop.empty()) {
+                std::cerr << "  [skip] alignment failed: " << img_file.path().filename() << "\n";
+                continue;
+            }
+
+            Embedding emb = arcface.embed_one(crop);
+            actor.embeddings.push_back(emb);
+            actor.source_images.push_back(img_file.path().filename().string());
+
+            std::cerr << "  [ok] " << img_file.path().filename()
+                      << "  conf=" << best.confidence << "\n";
+        }
+
+        if (actor.embeddings.empty()) {
+            std::cerr << "  [warn] no valid embeddings for " << name << " — skipped\n";
+            continue;
+        }
+
+        std::cerr << "  → " << actor.embeddings.size() << " embeddings\n";
+        gallery.actors.push_back(std::move(actor));
+    }
+
+    std::cerr << "[build_gallery] total: " << gallery.actors.size() << " actors\n";
+    return gallery;
+}