Di Ubuntu 26.04, repo resmi sudah pakai OpenCV lebih baru (≈4.10), jadi kalau kamu mau **OpenCV 4.6**, cara paling aman adalah **build manual dengan prefix terpisah** supaya tidak bentrok dengan versi sistem.

Berikut setup yang **stabil + rapi + tidak konflik** 👇

---

# 🎯 Strategi yang benar

* ❌ Jangan timpa `/usr` (punya apt)
* ✅ Install ke lokasi khusus: `/opt/opencv-4.6`
* ✅ Gunakan `PKG_CONFIG_PATH` untuk memilih versi

---

# 🚀 1. Install dependency

```bash
sudo apt update
sudo apt install -y build-essential cmake git pkg-config
```

---

# 📥 2. Download OpenCV 4.6

```bash
git clone https://github.com/opencv/opencv.git
cd opencv
git checkout 4.6.0
mkdir build && cd build
```

---

# ⚙️ 3. Konfigurasi minimal (ringan + stabil)

## 👉 Profil cocok untuk Go / ArUco

```bash
cmake .. \
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_INSTALL_PREFIX=/opt/opencv-4.6 \
-DBUILD_LIST=core,imgproc,imgcodecs,calib3d,aruco \
-DBUILD_SHARED_LIBS=ON \
-DWITH_IPP=OFF \
-DWITH_TBB=OFF \
-DWITH_OPENMP=ON \
-DWITH_CUDA=OFF \
-DWITH_OPENCL=OFF \
-DWITH_FFMPEG=OFF \
-DWITH_GSTREAMER=OFF \
-DWITH_QT=OFF \
-DWITH_GTK=OFF \
-DBUILD_TESTS=OFF \
-DBUILD_PERF_TESTS=OFF \
-DBUILD_EXAMPLES=OFF \
-DBUILD_JAVA=OFF \
-DBUILD_opencv_python=OFF
```

---

# 🔨 4. Build & install

```bash
make -j$(nproc)
sudo make install
sudo ldconfig
```

---

# 🔗 5. Aktifkan OpenCV 4.6 (penting)

## Temporary:

```bash
export PKG_CONFIG_PATH=/opt/opencv-4.6/lib/pkgconfig
export LD_LIBRARY_PATH=/opt/opencv-4.6/lib:$LD_LIBRARY_PATH
```

## Permanen:

```bash
echo 'export PKG_CONFIG_PATH=/opt/opencv-4.6/lib/pkgconfig' >> ~/.bashrc
echo 'export LD_LIBRARY_PATH=/opt/opencv-4.6/lib:$LD_LIBRARY_PATH' >> ~/.bashrc
source ~/.bashrc
```

---

# 🧪 6. Verifikasi

```bash
pkg-config --modversion opencv4
```

👉 Harus keluar:

```
4.6.0
```

---

# 🚀 7. Build ulang Go / C++ kamu

```bash
go clean -cache -modcache -i -r
go build -o aruco
```

atau C++:

```bash
g++ aruco.cpp -o aruco `pkg-config --cflags --libs opencv4`
```

---

# ⚠️ Hal penting (biar tidak error lagi)

* Jangan campur:

  * `/usr/lib` (OpenCV 4.10 dari apt)
  * `/opt/opencv-4.6` (manual)
* Selalu set `PKG_CONFIG_PATH`
* Selalu rebuild setelah ganti versi

---

# 🧠 Tips pro

Kalau mau switch versi:

```bash
# pakai 4.6
export PKG_CONFIG_PATH=/opt/opencv-4.6/lib/pkgconfig

# balik ke system (4.10)
export PKG_CONFIG_PATH=/usr/lib/x86_64-linux-gnu/pkgconfig
```

---

# 🏁 Kesimpulan

✔ Bisa install OpenCV 4.6 di Ubuntu 26.04
✔ Jangan pakai apt → harus build manual
✔ Gunakan prefix `/opt` biar clean
✔ Aman dipakai bareng Go / GoCV

---

Kalau mau, saya bisa bantu:

* bikin script otomatis install (1x jalan langsung beres)
* atau buat Docker image Go + OpenCV 4.6 super ringan (production-ready)