some question about channel message

[wqklihbf]

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System information

• OS Platform and Distribution (e.g., Linux Ubuntu 18.04):Linux Ubuntu 20.04
• Apollo installed from (source or binary): source
• Apollo version (3.5, 5.0, 5.5, 6.0): 8.0.0
• Output of apollo.sh config if on master branch:

Steps to reproduce the issue:

• Please use bullet points and include as much details as possible:

Supporting materials (screenshots, command lines, code/script snippets):

我在进行Apollo和Carla的联合仿真，在使用cyber_montior查看数据通道时发现/apollo/sensor/gnss/best_pose数据通道只有这些数据： 我在Carla官网发现gnss传感器的数据只包括经纬度与高度，那么其它的数据我要怎么获得呢？比如latitude_std_dev, sol_status, sol_type, num_sats_in_solution等 此外，measurement_time与timestamp_sec也有差别，这两个时间需要相等吗？

[daohu527]

Apollo Gnss message

The following table shows the messages that Apollo parses and publishes from the hardware. Carla simulates "gnss driver data"

raw hardware data	gnss driver data	MSF	NDT	RTK	Remark
GnssBestPose	GnssBestPose	✓			raw Gps
Gnss	GnssStatus
Ins	InsStatus
Ins	CorrectedImu			✓
Imu	Imu	✓			raw IMU
Ins	Gps		✓	✓
InsStat	InsStat		✓	✓
GnssEphemeris	GnssEphemeris	✓
EpochObservation	EpochObservation	✓
Heading	Heading	✓

Answer

The full message from GnssBestPose is as follows

https://github.com/ApolloAuto/apollo/blob/master/modules/common_msgs/sensor_msgs/gnss_best_pose.proto

I think carla assumes minimal message output and omits other fields.

[wqklihbf]

Apollo Gnss message

The following table shows the messages that Apollo parses and publishes from the hardware. Carla simulates "gnss driver data"

raw hardware data gnss driver data MSF NDT RTK Remark GnssBestPose GnssBestPose ✓ raw Gps Gnss GnssStatus Ins InsStatus Ins CorrectedImu ✓ Imu Imu ✓ raw IMU Ins Gps ✓ ✓ InsStat InsStat ✓ ✓ GnssEphemeris GnssEphemeris ✓ EpochObservation EpochObservation ✓ Heading Heading ✓

Answer

The full message from GnssBestPose is as follows

https://github.com/ApolloAuto/apollo/blob/master/modules/common_msgs/sensor_msgs/gnss_best_pose.proto

I think carla assumes minimal message output and omits other fields.

谢谢你的回复。很抱歉我还有一个问题。我发现/apollo/localization/pose通道在仿真时会有两种数据，因为这个通道的数据会不断地闪烁变化。一种是

header:
           timestamp_sec:
           frame_id: novatel

另一种是

header:
           timestamp_sec:
           frame_id: localization
           sequence_num:

这是否是因为有两个writer在向该通道写入数据，一个是Carla，一个是Apollo？ 我在使用脚本msf_simple_map_creator.sh创建msf_localization需要的local_map，这是否会有影响？ 期待你的回复。

[boyang9602]

按我的理解，novatel是apollo上的一个硬件设备，它可以做定位; Apollo自己也有一个定位模块，使用novatel的一些数据(IMU, GNSS)加上LiDAR来做定位。有可能不加LiDAR，看具体配置 https://github.com/ApolloAuto/apollo/tree/master/modules/localization