MV-DLS1400P 
4000 × 3000@RGB图
1920 × 1456@深度图

使用下面代码转换后点云图像也是4000*3000（处理太耗时间），如何得到1920 × 1456的点云图像（RGB对齐）

if(ImageType_Depth == stFrameData.stImageData[i].enImageType)
{
    MV3D_RGBD_IMAGE_DATA stPointCloudImage = {};
    int nRet = MV3D_RGBD_MapDepthToPointCloud(m_handle, &stFrameData.stImageData[i], &stPointCloudImage);
    if (MV3D_RGBD_OK != nRet) break;
    convertToPCL(stPointCloudImage, *cloud);
}

//Hiviwer 中实例代码

void convertToPCL(const MV3D_RGBD_IMAGE_DATA& stPointCloud, pcl::PointCloud<pcl::PointXYZ>& pclPointCloud)
{
pcl::PCLPointCloud2 pclCloud2;
pclCloud2.height = stPointCloud.nHeight;
pclCloud2.width = stPointCloud.nWidth;
pclCloud2.point_step = sizeof(POINT_XYZ);
pclCloud2.row_step = sizeof(POINT_XYZ) * stPointCloud.nWidth;

pclCloud2.fields.reserve(3);
pclCloud2.fields.push_back(createPointField("x", offsetof(POINT_XYZ, fX), pcl::PCLPointField::PointFieldTypes::FLOAT32, 1));
pclCloud2.fields.push_back(createPointField("y", offsetof(POINT_XYZ, fY), pcl::PCLPointField::PointFieldTypes::FLOAT32, 1));
pclCloud2.fields.push_back(createPointField("z", offsetof(POINT_XYZ, fZ), pcl::PCLPointField::PointFieldTypes::FLOAT32, 1));

pclCloud2.data.resize(pclCloud2.row_step * stPointCloud.nHeight);
memcpy(pclCloud2.data.data(), stPointCloud.pData, stPointCloud.nDataLen);
pcl::fromPCLPointCloud2(pclCloud2, pclPointCloud);
return;
}