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OSM ready for review

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sergi-e 2020-04-15 10:19:36 +02:00 committed by Marc Garcia Puig
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Docs/adv_opendrive.md
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@ -18,10 +18,6 @@ The resulting mesh describes the road definition in a minimalistic manner. All t
Traffic lights, stops and yields will be generated on the fly, as happens when using any map. Pedestrians will navigate over the sidewalks and crosswalks that appear in the map. All of these elements, and every detail on the road, are based on the OpenDRIVE file. As the standalone mode uses the `.xodr` directly, any issues in it will propagate to the simulation. This could be an issue especially at junctions, where many lanes are mixed.
* OpenDRIVE maps created with RoadRunner present some issues related to tilted junction ---> ESTE ES EL PROBLEMA DE LAS JUNCTIONS? SOLUCIONADO?
* No lateral slope.
* The sidewalks height is currently hardcoded. This ensures collisions with them are detected even if the map definition does not include this field ??
!!! Important
It is especially important to double check the OpenDRIVE file. Any issues in it will propagate when running the simulation.
@ -30,16 +26,16 @@ Traffic lights, stops and yields will be generated on the fly, as happens when u
---
## Run a standalone map
In order to open an OpenDRIVE file, the Python API includes now the method [`client.generate_opendrive_world()`](python_api.md#carla.Client.generate_opendrive_world). This will block the simulation until the new one is ready. The method needs for two parameters.
Open an OpenDRIVE file is just a matter of calling [`client.generate_opendrive_world()`](python_api.md#carla.Client.generate_opendrive_world) through the API. This will generate the new map, and block the simulation until it is ready. The method needs for two parameters.
* __`opendrive`__ is the content of the OpenDRIVE file parsed as a string.
* __`parameters`__ is a [carla.OpendriveGenerationParameters](python_api.md#carla.OpendriveGenerationParameters) containing settings for the generation of the mesh.
* __`vertex_distance`__ is the distance between the vertices of the mesh. The bigger, the distance, the more inaccurate the mesh will be. However, if the distance is too small, the resulting mesh will be too heavy to work with.
* __`max_road_length`__ is the maximum length of a portion of the mesh. The mesh is divide in portions to reduce rendering overhead. If a portion is not visible, UE will not render it. The smaller the portions, the more probably they are discarded. However, if the portions are too small, UE will have too many objects to manage, and performance will be affected too.
* __`wall_height`__ states the height of the additional walls created on the boundaries of the road. These prevent vehicles from falling to the void.
* __`additional_width`__ is an small width increment applied to the junction lanes. This is a safety measure to prevent vehicles from falling.
* __`smooth_junctions`__ if __True__, some information of the OpenDRIVE will be reinterpreted to smooth the final mesh at junctions. This is done to prevent some inaccuracies that may occur when various lanes meet. If set to __False__, the mesh will be generated exactly as described in the OpenDRIVE.
* __`enable_mesh_visibility`__ if __False__, the mesh will not be rendered, which could save a lot of work to the simulator.
* __`vertex_distance`__ *(default 2.0)* — Distance between the vertices of the mesh. The bigger, the distance, the more inaccurate the mesh will be. However, if the distance is too small, the resulting mesh will be too heavy to work with.
* __`max_road_length`__ *(default 50.0)* — Maximum length of a portion of the mesh. The mesh is divide in portions to reduce rendering overhead. If a portion is not visible, UE will not render it. The smaller the portions, the more probably they are discarded. However, if the portions are too small, UE will have too many objects to manage, and performance will be affected too.
* __`wall_height`__ *(default 1.0)* — Height of the additional walls created on the boundaries of the road. These prevent vehicles from falling to the void.
* __`additional_width`__ *(default 0.6)* — Small width increment applied to the junction lanes. This is a safety measure to prevent vehicles from falling.
* __`smooth_junctions`__ *(default True)* — If __True__, some information of the OpenDRIVE will be reinterpreted to smooth the final mesh at junctions. This is done to prevent some inaccuracies that may occur when various lanes meet. If set to __False__, the mesh will be generated exactly as described in the OpenDRIVE.
* __`enable_mesh_visibility`__ *(default True)* — If __False__, the mesh will not be rendered, which could save a lot of work to the simulator.
In order to easily test this feature, the `config.py` script in `PythonAPI/util/` has a new argument, `-x` or `--xodr-path`. This argument contains a string with the path to the `.xodr` file. If the mesh is generated with this script, the parameters used will always be the default ones.
@ -56,11 +52,15 @@ python3 config.py -x path/to/some/file.xodr
The generation of the mesh is the key element of this mode. The feature can only be successful if the resulting mesh is smooth and fits its definition perfectly. For that reason, this step is constantly being improved. In the last iterations, junctions have been polished to avoid inaccuracies that occur, especially where uneven lanes joined.
![opendrive_meshissue](img/opendrive_meshissue.png)
<div style="text-align: right"><i>When generating junction meshes, higher lanes tend to block the ones below them. <br>The parameter <code>smooth_junctions</code> avoids this kind of issue.</i></div>
<div style="text-align: right"><i>When generating junction meshes, higher lanes tend to block the ones below them. <br>The parameter <code>smooth_junctions</code> prevents this kind of issue.</i></div>
Besides that, instead of creating the whole map as a unique mesh, different fragments are created. Working smaller prevents unexpected issues. Also, by dividing the mesh, not all of it has to be rendered at a time. This is a step towards a larger goal, where the feature will be able to generate huge maps.
Besides that, instead of creating the whole map as a unique mesh, different portions are created. By dividing the mesh, the simulator can avoid rendering portions that are not visible, and save up costs. Working smaller also allows to generate huge maps and contain issues that may occur on a small portion of the mesh.
Regarding the current state of the mesh generation, some considerations should be taken into account.
* __Junction smoothing__. The default smoothing prevents the issues at tilted junctions described above. However, it will modify the original mesh in the process. Set `smooth_junctions` to __False__ to disable the smoothing if preferred.
* __Lateral slope__. This feature is currently not integrated in CARLA.
* __Sidewalk height__. This is currently hard-coded for all the sidewalks the same. Sidewalks must be higher than the road level for collisions to be detected, but RoadRunner does not export this value to the OpenDRIVE file. The height is hard-coded to guarantee collisions.
---
That covers all there is to know so far, regarding the OpenDRIVE standalone mode. Take the chance and use any OpenDRIVE map to test it in CARLA.