技术点

图片拼接成全景大图， 只要是使用了 opencv 中的 stitcher 类进行识别及合成。 其流程如下：
在这里插入图片描述

实现

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bool bitmapToMatrix(JNIEnv *env, jobject obj_bitmap, cv::Mat &matrix) {
    void *bitmapPixels;                                            // Save picture pixel data
    AndroidBitmapInfo bitmapInfo;                                   // Save picture parameters

    ASSERT_FALSE(AndroidBitmap_getInfo(env, obj_bitmap, &bitmapInfo) >=
                 0);        // Get picture parameters
    ASSERT_FALSE(bitmapInfo.format == ANDROID_BITMAP_FORMAT_RGBA_8888
                 || bitmapInfo.format ==
                    ANDROID_BITMAP_FORMAT_RGB_565);          // Only ARGB? 8888 and RGB? 565 are supported
    ASSERT_FALSE(AndroidBitmap_lockPixels(env, obj_bitmap, &bitmapPixels) >=
                 0);  // Get picture pixels (lock memory block)
    ASSERT_FALSE(bitmapPixels);

    if (bitmapInfo.format == ANDROID_BITMAP_FORMAT_RGBA_8888) {
        cv::Mat tmp(bitmapInfo.height, bitmapInfo.width, CV_8UC4,
                    bitmapPixels);    // Establish temporary mat
        tmp.copyTo(
                matrix);                                                         // Copy to target matrix
    } else {
        cv::Mat tmp(bitmapInfo.height, bitmapInfo.width, CV_8UC2, bitmapPixels);
        cv::cvtColor(tmp, matrix, cv::COLOR_BGR5652RGB);
    }

    //convert RGB to BGR
    cv::cvtColor(matrix, matrix, cv::COLOR_RGB2BGR);
    AndroidBitmap_unlockPixels(env, obj_bitmap);            // Unlock
    return true;
}


bool matrixToBitmap(JNIEnv *env, cv::Mat &matrix, jobject obj_bitmap) {
    void *bitmapPixels;                                            // Save picture pixel data
    AndroidBitmapInfo bitmapInfo;                                   // Save picture parameters

    ASSERT_FALSE(AndroidBitmap_getInfo(env, obj_bitmap, &bitmapInfo) >=
                 0);        // Get picture parameters
    ASSERT_FALSE(bitmapInfo.format == ANDROID_BITMAP_FORMAT_RGBA_8888
                 || bitmapInfo.format ==
                    ANDROID_BITMAP_FORMAT_RGB_565);          // Only ARGB? 8888 and RGB? 565 are supported
    ASSERT_FALSE(matrix.dims == 2
                 && bitmapInfo.height == (uint32_t) matrix.rows
                 && bitmapInfo.width ==
                    (uint32_t) matrix.cols);                   // It must be a 2-dimensional matrix with the same length and width
    ASSERT_FALSE(matrix.type() == CV_8UC1 || matrix.type() == CV_8UC3 || matrix.type() == CV_8UC4);
    ASSERT_FALSE(AndroidBitmap_lockPixels(env, obj_bitmap, &bitmapPixels) >=
                 0);  // Get picture pixels (lock memory block)
    ASSERT_FALSE(bitmapPixels);

    if (bitmapInfo.format == ANDROID_BITMAP_FORMAT_RGBA_8888) {
        cv::Mat tmp(bitmapInfo.height, bitmapInfo.width, CV_8UC4, bitmapPixels);
        switch (matrix.type()) {
            case CV_8UC1:
                cv::cvtColor(matrix, tmp, cv::COLOR_GRAY2RGBA);
                break;
            case CV_8UC3:
                cv::cvtColor(matrix, tmp, cv::COLOR_RGB2RGBA);
                break;
            case CV_8UC4:
                matrix.copyTo(tmp);
                break;
            default:
                AndroidBitmap_unlockPixels(env, obj_bitmap);
                return false;
        }
    } else {
        cv::Mat tmp(bitmapInfo.height, bitmapInfo.width, CV_8UC2, bitmapPixels);
        switch (matrix.type()) {
            case CV_8UC1:
                cv::cvtColor(matrix, tmp, cv::COLOR_GRAY2BGR565);
                break;
            case CV_8UC3:
                cv::cvtColor(matrix, tmp, cv::COLOR_RGB2BGR565);
                break;
            case CV_8UC4:
                cv::cvtColor(matrix, tmp, cv::COLOR_RGBA2BGR565);
                break;
            default:
                AndroidBitmap_unlockPixels(env, obj_bitmap);
                return false;
        }
    }
    AndroidBitmap_unlockPixels(env, obj_bitmap);                // Unlock
    return true;
}

extern "C"
JNIEXPORT jint JNICALL
Java_cn_xiaoxige_opencvdemo2_MainActivity_tmpStitchBitMap(JNIEnv *env, jobject thiz,
                                                          jobjectArray bitmaps) {
    try {
        vector<Mat> mats;
        int size = env->GetArrayLength(bitmaps);
        mats.reserve(size);
        for (int i = 0; i < size; ++i) {
            Mat mat;
            if (bitmapToMatrix(env, env->GetObjectArrayElement(bitmaps, i), mat)) {
                mats.push_back(mat);
            }
        }
        Ptr<Stitcher> stitcher = Stitcher::create();
        if (stitcher == nullptr) return -1;

        auto *matcher = new detail::BestOf2NearestMatcher(false, 0.5f);
        stitcher->setFeaturesMatcher(matcher);
        stitcher->setBundleAdjuster(new detail::BundleAdjusterRay());
        stitcher->setSeamFinder(new detail::NoSeamFinder);
        stitcher->setExposureCompensator(new detail::NoExposureCompensator());//曝光补偿
        stitcher->setBlender(new detail::FeatherBlender());
        Mat mat;
        Stitcher::Status state = stitcher->stitch(mats, mat);
        return state;
    } catch (...) {
        return -1;
    }
}

核心代码也就两行

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Ptr<Stitcher> stitcher = Stitcher::create();
Stitcher::Status state = stitcher->stitch(mats, mat);