Lidar Data Requirements

Lidar point cloud data can be used to reconstruct Gaussian Splatting and 3D textured model results. Callers need to write the data required for reconstruction into a JSON file in the specified format.

Required data includes:

✅ Point Cloud Data: Usually point cloud data in LAS format
✅ Trajectory Data: Usually in txt format, storing timestamp and position X/Y/Z per line
✅ Image Data: Image collection
✅ Image POS: Image position XYZ and attitude angle data
✅ Camera Parameters: Camera focal length, principal point internal parameters, and distortion parameters

LIDAR Reconstruction Parameters

Parameter Name	Type	Required	Description
`coordinate_system`	JSON	Yes	Coordinate system of image POS, see coordinate_system for details
`camera_meta_data`	JSON	Yes	Camera parameters, see camera_meta_data for details
`image_meta_data`	JSON	Yes	Image collection, see image_meta_data for details
`lidar_data`	JSON	Yes	Lidar data, see lidar_data for details

coordinate_system Object

Field Name	Type	Description	Example Value
`type`	int	Coordinate system type: 0=LocalENU, 1=Local, 2=Geographic, 3=Projected, 4=ECEF	2
`type_name`	string	Coordinate system type name (optional, auxiliary description)	"Geographic"
`label`	string	Coordinate system name (optional)	"WGS 84"
`epsg_code`	int	EPSG code (required for geographic/projected/geocentric coordinate systems)	4326
`wkt`	string	WKT string (optional, alternative to epsg_code)	"..."
`origin_point`	array[3]	Origin WGS84 coordinates [longitude, latitude, elevation] (required only when type=0 LocalENU)	[114.12, 22.12, 0]
`offset`	array[3]	Coordinate system origin offset (optional)	[0, 0, 0]

如下为最常见的WGS84和CGCS2000坐标系：

{
  "type": 2,              // 0=LocalENU, 1=Local, 2=Geographic, 3=Projected
  "type_name": "Geographic",
  "label": "WGS 84",     // Coordinate system name
  "epsg_code": 4326      // EPSG code
}
{
  "type": 3,              // 0=LocalENU, 1=Local, 2=Geographic, 3=Projected
  "type_name": "Projected",
  "label": "WGS 84 / UTM zone 50N",     // Coordinate system name
  "epsg_code": 32650      // EPSG code
}
{
  "type": 2,              // 0=LocalENU, 1=Local, 2=Geographic, 3=Projected
  "type_name": "Geographic",
  "label": "CGCS2000",     // Coordinate system name
  "epsg_code": 4490      // EPSG code
}
{
  "type": 2,              // 0=LocalENU, 1=Local, 2=Geographic, 3=Projected
  "type_name": "Projected",
  "label": "CGCS2000 / 3-degree Gauss-Kruger CM 114E",     // Coordinate system name
  "epsg_code": 4547      // EPSG code
}

camera_meta_data Object

Field Name	Type	Required	Description
`id`	int	Yes	Camera unique ID
`meta_data`	object	Yes	Camera元信息，详见下表

meta_data 子字段说明：

Field Name	Type	Required	Description
`projection_model`	int	Yes	Lens model: 0-perspective lens (k1,k2,k3,p1,p2); 1-fisheye lens (k1,k2,k3,k4)
`camera_name`	string	Yes	Camera name
`width`	int	Yes	Sensor width (pixels)
`height`	int	Yes	Sensor height (pixels)
`parameters`	array	Yes	Camera internal parameter group (perspective camera order: fx, fy, cx, cy, k1, k2, k3, p1, p2; fisheye camera order: fx fy cx cy k1 k2 k3 k4)
`constant_parameters`	array	No	Array of parameter indices to fix camera internal parameters during AT solution, specified according to the parameter order in parameters (index starts from 0), e.g., for perspective camera, specifying [0,1,2,3,4,5,6,7,8] means fixing all parameters

透视镜头
"camera_meta_data": [
  {
    "id": 1,
    "meta_data": {
      "projection_model": 0,    // Perspective camera
      "camera_name": "common",
      "width": 5280,
      "height": 3956,
      "parameters": [
        3713.29,                // fx
        3713.29,                // fy
        2647.02,                // cx
        1969.28,                // cy
        -0.11257524,            // k1
        0.01487443,             // k2
        -0.00008572,            // k3
        1e-7,                   // p1
        -0.02706411             // p2
      ]
    }
  }
]
鱼眼镜头
"camera_meta_data": [
  {
    "id": 1,
    "meta_data": {
      "camera_name": "fisheye",         // Fisheye camera
      "projection_model": 1,
      "width": 3600,
      "height": 3600,
      "parameters": [
        982.7593599212141,              // fx
        982.7593599212141,              // fy
        1747.6373897301492,             // cx
        1806.4116030074354,             // cy
        0.03702410479839055,            // k1
        -0.016007338300982825,          // k2
        -1.0884582901480562e-05,        // k3
        -9.773097281093723e-05          // k4
      ]
    }
  }
]

image_meta_data Object

Field Name	Type	Required	Description
`id`	int	Yes	Image unique ID
`path`	string	Yes	Image absolute path
`meta_data`	object	Yes	Image元信息，详见下表

meta_data 子字段说明：

Field Name	Type	Required	Description
`width`	int	Yes	Image width (pixels)
`height`	int	Yes	Image height (pixels)
`camera_id`	int	Yes	Corresponding camera ID
`pos`	array[3]	Yes	POS position [longitude/X, latitude/Y, elevation/Z], must be specified for true-scale reconstruction
`pos_sigma`	array[3]	Yes	POS position accuracy (meters), RTK positioning: [0.03,0.03,0.06], regular GPS positioning: [2.0,2.0,5.0]. If RTK positioning data is used, it is strongly recommended to select RTK weight for highest accuracy
`orientation`	array[9]	No	3x3旋转矩阵（9个值，行主序，单位向量，世界坐标系到相机坐标系的旋转矩阵）
`position_constant`	bool	否	是否固定位置（true/false），固定位置意味着空三不会优化改变图像的位置，保持输入值
`dewarp_flag`	bool	否	畸变校正标志（true表示图像已去畸变）

lidar_data Data

Field Name	Type	Description
`coordinate_system`	JSON	Coordinate system definition for lidar data, LAS and trajectory files must use the same coordinate system
`laser_meta_data`	array	List of lidar point cloud file metadata
`trajectory_meta_data`	array	List of lidar trajectory data

laser_meta_data Sub-fields

Field Name	Type	Description
`id`	int	LAS point cloud data ID
`path`	string	LAS point cloud file path (supports LAS format)
`trajectory_id`	int	Associated trajectory ID

trajectory_meta_data Sub-fields

Field Name	Type	Description
`id`	int	Trajectory data ID
`trajectory_points`	array	Trajectory point data list

trajectory_points Sub-fields

Field Name	Type	Description
`pos`	array	Position coordinates [longitude/X, latitude/Y, elevation/Z]
`time`	double	Timestamp (seconds), must match the timestamp of LAS point cloud

Example:

{
  "coordinate_system": {
    "type": 2,
    "epsg_code": 4326
  },  
  "camera_meta_data": [
  {
    "id": 1,
    "meta_data": {
      "camera_name": "Left",
      "projection_model": 1,
      "width": 3600,
      "height": 3600,
      "parameters": [
        982.7593599212141,
        982.7593599212141,
        1747.6373897301492,
        1806.4116030074354,
        0.03702410479839055,
        -0.016007338300982825,
        -1.0884582901480562e-05,
        -9.773097281093723e-05
      ]
    }
  },
  {
    "id": 2,
    "meta_data": {
      "camera_name": "Right",
      "projection_model": 1,
      "width": 3600,
      "height": 3600,
      "parameters": [
        982.7593599212141,
        982.7593599212141,
        1747.6373897301492,
        1806.4116030074354,
        0.03702410479839055,
        -0.016007338300982825,
        -1.0884582901480562e-05,
        -9.773097281093723e-05
      ]
    }
  }
  ],
  "image_meta_data":[
    {
        "id": 1,
        "path": "\\left\\2390-195042-472_00395-L.JPG",
        "meta_data": {
        "width": 3600,
        "height": 3600,
        "camera_id": 1,
        "pos": [
            -2272303.077314121,
            5011055.355739306,
            3215292.943560472
        ],
        "pos_sigma": [0.03,0.03,0.06],
        "orientation": [
            0.8929275412022056,
            0.43070972182403255,
            0.13103259781004117,
            -0.4500241512548592,
            0.8457917052937085,
            0.2865565468519331,
            0.012596406230632032,
            -0.31484206641207435,
            0.9490604847782084
        ]
        }
    },
    {
        "id": 2,
        "path": "\\right\\2390-195042-472_00395-R.JPG",
        "meta_data": {
        "width": 3600,
        "height": 3600,
        "camera_id": 2,
        "pos": [
            -2272303.117693735,
            5011055.368901664,
            3215292.967908075
        ],
        "pos_sigma": [0.03,0.03,0.06],
        "orientation": [
            0.8918935649712837,
            0.435497387453275,
            0.12193397510204676,
            -0.4504120798442928,
            0.8311302214603127,
            0.3261157973874772,
            0.040679566039387514,
            -0.34578111645476495,
            0.9374329802231962
        ]
        }
    }
  ],
  "lidar_data": {
    "coordinate_system": {
      "type": 3,
      "epsg_code": 32632
    },
    "laser_meta_data": [            // 激光雷达点云文件列表
      {
        "id": 1,                    // 文件ID
        "path": "C:/path/to/file.las", // 点云文件路径
        "trajectory_id": 1          // 对应的轨迹ID
      }
    ],
    "trajectory_meta_data": [       // 激光雷达轨迹数据
      {
        "id": 1,                    // 轨迹ID
        "trajectory_points": [      // 轨迹点列表
          {
            "pos": [                // 位置坐标 [X, Y, Z]
              -2272285.667,
              5011024.157,
              3215249.921
            ],
            "time": 284833.06453    // 时间戳
          },
          ....
        ]
      }
    ]
  }
}

LIDAR Reconstruction Parameters​

coordinate_system Object​

camera_meta_data Object​

image_meta_data Object​

lidar_data Data​

laser_meta_data Sub-fields​

trajectory_meta_data Sub-fields​

trajectory_points Sub-fields​