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apollo介绍之map模块(二)

本章主要介绍下apollo代码的map模块,map的代码目录结构如下

├── data // 生成好的地图
│ └── demo
├── hdmap // 高精度地图
│ ├── adapter // 从xml文件读取地图(opendrive保存格式为xml)
│ │ └── xml_parser
│ └── test-data
├── pnc_map // 给规划控制模块用的地图
│ └── testdata
├── proto // 地图各元素的消息格式(人行横道,车道线等)
├── relative_map // 相对地图
│ ├── common
│ ├── conf
│ ├── dag
│ ├── launch
│ ├── proto
│ ├── testdata
│ │ └── multi_lane_map
│ └── tools
├── testdata // 测试数据?
│ └── navigation_dummy
└── tools // 工具

apollo的高精度地图采用了opendrive格式,opendrive是一个统一的地图标准,这样保证了地图的通用性。其中map模块主要提供的功能是读取高精度地图,并且转换成apollo程序中的Map对象。直白一点就是说把xml格式的opendrive高精度地图,读取为程序能够识别的格式。

map模块没有实现的功能是高精度地图的制作,简略的制图过程可以[参考](王方浩:高精度地图制作)。

由于opendrive格式是一个标准,可以它的参考官方网站。下面主要介绍下apollo是如何读取xml地图,并且使用的。

地图的读取在adapter中,其中xml_parser目录提供解析xml的能力。而http://opendrive_adapter.cc则实现了地图的加载,转换为程序中的Map对象。然后地图在http://hdmap_impl.cc中提供一系列api接口给其他模块使用。

下面先介绍下地图消息格式,主要在proto目录

map.proto 分为地图头部信息和结构体,头部信息主要介绍了地图的基本信息“版本,时间,投影方法,地图大小,厂家等”。结构体主要是道路的不同组成部分,包括“人行横道,路口区域,车道,停车观察,信号灯,让路标志,重叠区域,禁止停车,减速带,道路,停车区域,路边的小路,或者行人走的路”。

首先是地图的基本信息

message Header {
optional bytes version = 1; //地图版本
optional bytes date = 2; //地图时间
optional Projection projection = 3; //投影方法
optional bytes district = 4; //区
optional bytes generation = 5; //
optional bytes rev_major = 6; //
optional bytes rev_minor = 7; //
optional double left = 8; //左
optional double top = 9; //上
optional double right = 10; //右
optional double bottom = 11; //底
optional bytes vendor = 12; //供应商
}

下面是地图的道路信息,其中有2个标志(StopSign,YieldSign)是美国才有的,后来查看了下知乎发现对应到国内是(停,让),具体的含义都是一样,停车的意思是到路口先停止,看下有没有车,然后再开始启动,让车就是先让行,比如交汇路口,理应让直行的车辆先通过,然后再汇入道路。[参考](国内为什么不能采用美国的stop sign制度在很多路口设置呢?)

下面在介绍下overlap,overlap在注释里的解释是“任何一对在地图上重合的东西,包括(车道,路口,人行横道)”,比如路口的人行横道和道路是重叠的,还有一些交通标志和道路也是重叠的,这是创造的一个逻辑概念。(不知道这样理解是否正确)

message Map {
optional Header header = 1; //上面所说的地图基本信息
repeated Crosswalk crosswalk = 2; //人行横道
repeated Junction junction = 3; //交叉路口
repeated Lane lane = 4; //车道
repeated StopSign stop_sign = 5; //停车标志
repeated Signal signal = 6; //信号灯
repeated YieldSign yield = 7; //让车标志
repeated Overlap overlap = 8; //重叠区域
repeated ClearArea clear_area = 9; //禁止停车区域
repeated SpeedBump speed_bump = 10; //减速带
repeated Road road = 11; //道路
repeated ParkingSpace parking_space = 12; //停车区域
repeated Sidewalk sidewalk = 13; //路边的小路,或者行人走的路,现在的版本已经去掉?但是其他模块有些还有sidewalk
}

map_crosswalk.proto 人行横道(google图片搜索出了彩虹人行横道和三维人行横道,就问深度学习该怎么办?)

message Crosswalk {
optional Id id = 1; //编号
optional Polygon polygon = 2; //多边形
repeated Id overlap_id = 3; //重叠ID
}

map_junction.proto 路口,道路汇聚点

message Junction {
optional Id id = 1; //编号
optional Polygon polygon = 2; //多边形
repeated Id overlap_id = 3; //重叠id
}

map.lane.proto 车道线,介绍的比较复杂

// A lane is part of a roadway, that is designated for use by a single line of vehicles.
// Most public roads (include highways) have more than two lanes.
message Lane {
optional Id id = 1; //编号
// Central lane as reference trajectory, not necessary to be the geometry central.
optional Curve central_curve = 2; //中心曲线
// Lane boundary curve.
optional LaneBoundary left_boundary = 3; //左边界
optional LaneBoundary right_boundary = 4; //右边界
// in meters.
optional double length = 5; //长度
// Speed limit of the lane, in meters per second.
optional double speed_limit = 6; //速度限制
repeated Id overlap_id = 7; //重叠区域id
// All lanes can be driving into (or from).
repeated Id predecessor_id = 8; //前任id
repeated Id successor_id = 9; //继任者id
// Neighbor lanes on the same direction.
repeated Id left_neighbor_forward_lane_id = 10; //左边相邻前方车道id
repeated Id right_neighbor_forward_lane_id = 11; //右边相邻前方车道id
enum LaneType { //车道类型
NONE = 1; //无
CITY_DRIVING = 2; //城市道路
BIKING = 3; //自行车
SIDEWALK = 4; //人行道
PARKING = 5; //停车
};
optional LaneType type = 12; //车道类型
enum LaneTurn {
NO_TURN = 1; //直行
LEFT_TURN = 2; //左转弯
RIGHT_TURN = 3; //右转弯
U_TURN = 4; //掉头
};
optional LaneTurn turn = 13; //转弯类型
repeated Id left_neighbor_reverse_lane_id = 14; //左边相邻反方向车道id
repeated Id right_neighbor_reverse_lane_id = 15; //右边相邻反方向车道id
optional Id junction_id = 16;
// Association between central point to closest boundary.
repeated LaneSampleAssociation left_sample = 17; //中心点与最近左边界之间的关联
repeated LaneSampleAssociation right_sample = 18; //中心点与最近右边界之间的关联
enum LaneDirection {
FORWARD = 1; //前
BACKWARD = 2; //后,潮汐车道借用的情况?
BIDIRECTION = 3; //双向
}
optional LaneDirection direction = 19; //车道方向
// Association between central point to closest road boundary.
repeated LaneSampleAssociation left_road_sample = 20; //中心点与最近左路边界之间的关联
repeated LaneSampleAssociation right_road_sample = 21; //中心点与最近右路边界之间的关联
}

map_stop_sign.proto 停止信号

message StopSign {
optional Id id = 1; //编号
repeated Curve stop_line = 2; //停止线,Curve曲线应该是基础类型
repeated Id overlap_id = 3; //重叠id
enum StopType {
UNKNOWN = 0; //未知
ONE_WAY = 1; //只有一车道可以停
TWO_WAY = 2;
THREE_WAY = 3;
FOUR_WAY = 4;
ALL_WAY = 5;
};
optional StopType type = 4;
}

map_signal.proto 交通信号标志

message Subsignal {
enum Type {
UNKNOWN = 1; //未知
CIRCLE = 2; //圈???
ARROW_LEFT = 3; //左边
ARROW_FORWARD = 4; //前面
ARROW_RIGHT = 5; //右边
ARROW_LEFT_AND_FORWARD = 6; //左前
ARROW_RIGHT_AND_FORWARD = 7; //右前
ARROW_U_TURN = 8; //掉头
};
optional Id id = 1;
optional Type type = 2;
// Location of the center of the bulb. now no data support.
optional apollo.common.PointENU location = 3; //也是基础类型?
}
message Signal {
enum Type {
UNKNOWN = 1;
MIX_2_HORIZONTAL = 2;
MIX_2_VERTICAL = 3;
MIX_3_HORIZONTAL = 4;
MIX_3_VERTICAL = 5;
SINGLE = 6;
};
optional Id id = 1;
optional Polygon boundary = 2; //多边形
repeated Subsignal subsignal = 3; //子信号
// TODO: add orientation. now no data support.
repeated Id overlap_id = 4; //重叠id
optional Type type = 5; //这里的类型是主要指交通标识的个数及位置??
// stop line
repeated Curve stop_line = 6; //在哪里结束?
}

map_yield_sign.proto 让行标志(美国才有)

message YieldSign {
optional Id id = 1; //编号
repeated Curve stop_line = 2; //在哪里结束
repeated Id overlap_id = 3; //重叠id
}

map_overlap.proto 这里只介绍了LaneOverlapInfo,其他的还没有对应的格式

message LaneOverlapInfo {
optional double start_s = 1; //position (s-coordinate)
optional double end_s = 2; //position (s-coordinate)
optional bool is_merge = 3;
}
// Information about one object in the overlap.
message ObjectOverlapInfo {
optional Id id = 1;
oneof overlap_info {
LaneOverlapInfo lane_overlap_info = 3;
SignalOverlapInfo signal_overlap_info = 4;
StopSignOverlapInfo stop_sign_overlap_info = 5;
CrosswalkOverlapInfo crosswalk_overlap_info = 6;
JunctionOverlapInfo junction_overlap_info = 7;
YieldOverlapInfo yield_sign_overlap_info = 8;
ClearAreaOverlapInfo clear_area_overlap_info = 9;
SpeedBumpOverlapInfo speed_bump_overlap_info = 10;
ParkingSpaceOverlapInfo parking_space_overlap_info = 11;
SidewalkOverlapInfo sidewalk_overlap_info = 12;
}
}
// Here, the "overlap" includes any pair of objects on the map
// (e.g. lanes, junctions, and crosswalks).
message Overlap {
optional Id id = 1;
// Information about one overlap, include all overlapped objects.
repeated ObjectOverlapInfo object = 2;
}

逻辑概念,没有具体的规则显示这个区域

map_clear_area.proto 禁止停车

// A clear area means in which stopping car is prohibited
message ClearArea {
optional Id id = 1; //编号
repeated Id overlap_id = 2; //重叠id
optional Polygon polygon = 3; //多边形
}

map_speed_bump.proto 减速带

message SpeedBump {
optional Id id = 1; //编号
repeated Id overlap_id = 2; //重叠区域
repeated Curve position = 3; //曲线位置
}

map_road.proto 道路的信息,是由一些RoadSection组成

// road section defines a road cross-section, At least one section must be defined in order to
// use a road, If multiple road sections are defined, they must be listed in order along the road
message RoadSection {
optional Id id = 1;
// lanes contained in this section
repeated Id lane_id = 2;
// boundary of section
optional RoadBoundary boundary = 3;
}
// The road is a collection of traffic elements, such as lanes, road boundary etc.
// It provides general information about the road.
message Road {
optional Id id = 1;
repeated RoadSection section = 2;
// if lane road not in the junction, junction id is null.
optional Id junction_id = 3;
}

map_parking.proto 停车区域

// ParkingSpace is a place designated to park a car.
message ParkingSpace {
optional Id id = 1;
optional Polygon polygon = 2;
repeated Id overlap_id = 3;
optional double heading = 4;
}

map_sidewalk.proto 路边的小路,或者行人走的路

// A sidewalk (American English) or pavement (British English), also known as a footpath or footway, is a path along the side of a road.
message Sidewalk {
optional Id id = 1;
repeated Id overlap_id = 2;
optional Polygon polygon = 3;
}

其中还剩下的4个没有介绍

map_id.proto

这里的map_id是基础id?

message Id {
optional string id = 1; //id,字符类型
}

map_speed_control.proto 限制速度

message SpeedControl {
optional string name = 1;
optional apollo.hdmap.Polygon polygon = 2;
optional double speed_limit = 3;
}

map_geometry.proto 地图的几何形状?

// Polygon, not necessary convex.
message Polygon {
repeated apollo.common.PointENU point = 1;
}
// Straight line segment.
message LineSegment {
repeated apollo.common.PointENU point = 1;
}
// Generalization of a line.
message CurveSegment {
oneof curve_type {
LineSegment line_segment = 1;
}
optional double s = 6; // start position (s-coordinate)
optional apollo.common.PointENU start_position = 7;
optional double heading = 8; // start orientation
optional double length = 9;
}
// An object similar to a line but that need not be straight.
message Curve {
repeated CurveSegment segment = 1;
}

map_pnc_junction.proto PNC路口(具体的场景是什么??)

message PNCJunction {
optional Id id = 1;
optional Polygon polygon = 2;
repeated Id overlap_id = 3;
}

上面只是简单的介绍了下地图的数据格式,具体的应用场景,还需要结合planning模块进一步学习。

我们再回过头来看adapter模块,其中xml_parser就是针对道路的不同元素部分做的解析。

├── adapter
│ ├── BUILD
│ ├── coordinate_convert_tool.cc // 坐标转换工具
│ ├── coordinate_convert_tool.h
│ ├── opendrive_adapter.cc // 加载opendrive格式地图
│ ├── opendrive_adapter.h
│ ├── proto_organizer.cc //
│ ├── proto_organizer.h
│ └── xml_parser // xml_parser针对道路的不同元素做相应解析
│ ├── common_define.h
│ ├── header_xml_parser.cc
│ ├── header_xml_parser.h
│ ├── junctions_xml_parser.cc
│ ├── junctions_xml_parser.h
│ ├── lanes_xml_parser.cc
│ ├── lanes_xml_parser.h
│ ├── objects_xml_parser.cc
│ ├── objects_xml_parser.h
│ ├── roads_xml_parser.cc
│ ├── roads_xml_parser.h
│ ├── signals_xml_parser.cc
│ ├── signals_xml_parser.h
│ ├── status.h
│ ├── util_xml_parser.cc
│ └── util_xml_parser.h

最后在看下hdmap_impl,主要实现了一系列的api来查找道路中的元素。由于实现的接口太多,后面有时间了看是否能够整理下api文档。

总结

其实我们只需要知道map模块的主要功能是“加载opendrive格式的地图,并且提供一系列的API给其他模块使用”。然后再根据具体的场景来了解地图各个部分的作用,就算是对map模块比较了解了。

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