CARLA Simulator: Difference between revisions
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The client handles setting up the scene and all sensor data. | The client handles setting up the scene and all sensor data. | ||
See [https://carla.readthedocs.io/en/latest/tuto_G_retrieve_data/ Tutorial: Retrieve Data] and scroll down to tutorial_ego.py. | See [https://carla.readthedocs.io/en/latest/tuto_G_retrieve_data/ Tutorial: Retrieve Data] and scroll down to tutorial_ego.py. | ||
;Notes | |||
* If you want a clean shutdown, you need to disable autopilot on the ego_vehicle before you destroy it. | |||
==Build From Source== | |||
To develop vehicles or make significant changes, you will want to build from source. | |||
{{hidden | Build From Source | | |||
See [https://carla.readthedocs.io/en/latest/build_linux/#linux-build-command-summary Linux build summary] | |||
* Get Unreal Engine cloning the UnrealEngine repo and building it. | |||
** You will need an Epic Games account linked to your GitHub to have access to the source code. | |||
* Clone the carla repo and download assets. | |||
<pre> | |||
# Launch Unreal Engine | |||
make launch | |||
# Build Carla | |||
make package | |||
</pre> | |||
}} | |||
==Sensors== | |||
[https://carla.readthedocs.io/en/latest/ref_sensors/ Sensors Reference] | |||
===RGB Image=== | |||
;Disabling Effects for Stitching | |||
See [https://github.com/carla-simulator/carla/issues/2185 Disable all lens simulating effects on cameras ] | |||
<pre> | |||
# carla/CarlaUE4/Config/DefaultEngine.ini | |||
# Add to section [/Script/Engine.RendererSettings] | |||
r.BlackBorders=0 | |||
r.DepthOfFieldQuality=0 | |||
r.DisableDistortion=1 | |||
r.MotionBlurQuality=0 | |||
r.SceneColorFringeQuality=0 # might be chromatic aberrations | |||
r.Tonemapper.Quality=0 # might be vignette | |||
</pre> | |||
===Depth Image=== | |||
Depths images encode as z-depth to camera as 8-bit images. | |||
To get the meters from the 8-bit RGB image, apply the following formula: | |||
<pre> | |||
normalized = (R + G * 256 + B * 256 * 256) / (256 * 256 * 256 - 1) | |||
in_meters = 1000 * normalized | |||
</pre> | |||
I recommend resaving the depth images as 16-bit PNG images. | |||
This makes the depth values less sensitive to rounding errors, even though 8-bit PNG images are lossless. | |||
To convert depth values to euclidean distance, you need to divide by \(\cos(\theta)\) where \(\theta\) is the angle to the center of the image. | |||
{{hidden | Z-depth to Euclidean Depth | | |||
See [https://github.com/carla-simulator/carla/issues/2287 https://github.com/carla-simulator/carla/issues/2287] for a formula to convert z-depth to euclidean depth. | |||
}} | |||
==Fixed time step== | ==Fixed time step== | ||
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However for simulations, you will want to fix the time between frames to a constant value. This allows faster-than-realtime simulations on more powerful hardware and slower-than-realtime simulations on slower hardware. | However for simulations, you will want to fix the time between frames to a constant value. This allows faster-than-realtime simulations on more powerful hardware and slower-than-realtime simulations on slower hardware. | ||
Below sets the timestep to <code>1/30</code> seconds per frame. | Below sets the timestep to <code>1/30</code> seconds per frame on the server. | ||
<pre> | <pre> | ||
./CarlaUE4.sh -benchmark -fps=30 | ./CarlaUE4.sh -benchmark -fps=30 | ||
</pre> | </pre> | ||
Alternatively, you can do this on the client by modifying the time step setting of your world. | |||
<pre> | |||
settings = world.get_settings() | |||
settings.fixed_delta_seconds = 0.05 | |||
world.apply_settings(settings) | |||
</pre> | |||
If your client needs to record data every frame, you may want to use [[#synchronous mode]]. | |||
==Synchronous Mode== | |||
Synchronous mode will force the server to wait for <code>world.tick()</code> on the client rather than run as fast as possible. | |||
This is ideal if you need to do something per-frame which causes your client to be slower than your server. | |||
<pre> | |||
settings = world.get_settings() | |||
settings.fixed_delta_seconds = 1 / 30 | |||
settings.synchronous_mode = True # Enables synchronous mode | |||
world.apply_settings(settings) | |||
</pre> | |||
If you are using the built in traffic manager for autopilot, you will need to set that to synchronous mode as well: | |||
<syntaxhighlight lang="python"> | |||
tm = client.get_trafficmanager() | |||
tm.set_synchronous_mode(True) | |||
</syntaxhighlight> | |||
See [https://github.com/carla-simulator/carla/blob/master/PythonAPI/examples/spawn_npc.py spawn_npc.py] for an example of synchronous mode. | |||
==Troubleshooting== | |||
* <code>trying to create rpc server for traffic manager; but the system failed to create because of bind error</code> on <code>client.get_trafficmanager()</code> | |||
** kill the program using port 8000 <code>lsof -i :8000</code> | |||
==Coordinate System== | |||
Carla is based on UE4 which uses a left-handed coordinate system. Specifically, up is +z, forward is +x, and right is +y. | |||
To convert (yaw, pitch, roll) rotations to a right-handed coordinate system, just use (-yaw, pitch, -roll) | |||