Method Create

src/colmap/feature/sift.cc:1263–1330

  }

  static std::unique_ptr<FeatureMatcher> Create(
      const FeatureMatchingOptions& options) {
    // SiftGPU uses many global static state variables and the initialization
    // must be thread-safe in order to work correctly. This is enforced here.
    static std::mutex mutex;
    std::lock_guard<std::mutex> lock(mutex);

    const std::vector<int> gpu_indices = CSVToVector<int>(options.gpu_index);
    THROW_CHECK_EQ(gpu_indices.size(), 1) << "SiftGPU can only run on one GPU";

    SiftGPU sift_gpu;
    sift_gpu.SetVerbose(0);

    auto matcher = std::make_unique<SiftGPUFeatureMatcher>(options);

    // Note that the SiftMatchGPU object is not movable (for whatever reason).
    // If we instead create the object here and move it to the constructor, the
    // program segfaults inside SiftMatchGPU.

    matcher->sift_match_gpu_ = SiftMatchGPU(options.max_num_matches);

#if defined(COLMAP_CUDA_ENABLED)
    if (gpu_indices[0] >= 0) {
      matcher->sift_match_gpu_.SetLanguage(
          SiftMatchGPU::SIFTMATCH_CUDA_DEVICE0 + gpu_indices[0]);
    } else {
      matcher->sift_match_gpu_.SetLanguage(SiftMatchGPU::SIFTMATCH_CUDA);
    }
    matcher->backend_ = SiftBackend::CUDA;
#else   // COLMAP_CUDA_ENABLED
    matcher->sift_match_gpu_.SetLanguage(SiftMatchGPU::SIFTMATCH_GLSL);
    matcher->backend_ = SiftBackend::GLSL;
#endif  // COLMAP_CUDA_ENABLED

    if (matcher->sift_match_gpu_.VerifyContextGL() == 0) {
      return nullptr;
    }

    if (!matcher->sift_match_gpu_.Allocate(options.max_num_matches,
                                           options.sift->cross_check)) {
      LOG(ERROR) << StringPrintf(
          "Not enough GPU memory to match %d features. "
          "Reduce the maximum number of matches.",
          options.max_num_matches);
      return nullptr;
    }

#if !defined(COLMAP_CUDA_ENABLED)
    if (matcher->sift_match_gpu_.GetMaxSift() < options.max_num_matches) {
      LOG(WARNING) << StringPrintf(
          "OpenGL version of SiftGPU only supports a "
          "maximum of %d matches - consider changing to CUDA-based "
          "feature matching to avoid this limitation.",
          matcher->sift_match_gpu_.GetMaxSift());
    }
#endif  // COLMAP_CUDA_ENABLED

    matcher->sift_match_gpu_.gpu_index = gpu_indices[0];