70 lines
3.2 KiB
Markdown
70 lines
3.2 KiB
Markdown
# How to generate the pedestrian navigation info
|
|
|
|
---
|
|
## Introduction
|
|
|
|
The pedestrians to walk need information about the map in a specific format. That file that describes the map for navigation is a binary file with extension `.BIN`, and they are saved in the **Nav** folder of the map. Each map needs a `.BIN` file with the same name that the map, so automatically can be loaded with the map.
|
|
|
|
This `.BIN` file is generated from the Recast & Detour library and has all the information that allows pathfinding and crow management.
|
|
|
|
If we need to generate this `.BIN` file for a custom map, we need to follow this process:
|
|
|
|
* Export the map meshes
|
|
* Rebuild the `.BIN` file with RecastBuilder
|
|
* Copy the `.BIN` file in a `Nav/` folder with the map
|
|
|
|
---
|
|
## Export meshes
|
|
|
|
We have several types of meshes for navigation. The meshes need to be identified as one of those types, using specific nomenclature.
|
|
|
|
| Type | Start with | Description |
|
|
|-----------|------------|-------------|
|
|
| Ground | `Road_Sidewalk` | Pedestrians can walk over these meshes freely (sidewalks...). |
|
|
| Grass | `Road_Crosswalk` | Pedestrians can walk over these meshes but as a second option if no ground is found. |
|
|
| Road | `Road_Grass` | Pedestrians won't be allowed to walk on it unless we specify some percentage of pedestrians that will be allowed. |
|
|
| Crosswalk | `Road_Road`, `Road_Curb`, `Road_Gutter` or `Road_Marking` | Pedestrians can cross the roads only through these meshes. |
|
|
| Block | any other name | Pedestrians will avoid these meshes always (are obstacles like traffic lights, trees, houses...). |
|
|
|
|
<br>
|
|
|
|
For instance, all road meshes need to start with `Road_Road` e.g: `Road_Road_Mesh_1`, `Road_Road_Mesh_2`...
|
|
|
|
This nomenclature is used by RoadRunner when it exports the map, so we are just following the same.
|
|
|
|
Also, we don't need to export meshes that are not of interest by the navigation system, like landscapes where pedestrians will not walk, or UE4's _sky domes_, rivers, lakes and so on.
|
|
We can **tag** any mesh with the name **NoExport** and then the exporter will ignore that mesh.
|
|
|
|
Once we have all meshes with the proper nomenclature and tagged the ones that we want to ignore, we can call the Carla Exporter that is found under the `File > Actors > Carla Exporter`:
|
|
|
|
|
|
|
|
The `.OBJ` file will be saved with the name of the map with extension OBJ in the **CarlaUE4/Saved** folder of UE4.
|
|
|
|
---
|
|
## Rebuild the navigation binary
|
|
|
|
With Recast & Detour library comes an executable file that needs to be used to generate the final `.BIN` file.
|
|
The executable uses by default the parameters to work on Carla, and you only need to pass as parameter the `.OBJ` you exported above, and the `.BIN` will be created.
|
|
|
|
You can find the executable, on the `Carla/Build/recast-{version}-install/bin/` folder, already compiled when Carla was installed.
|
|
|
|
Run:
|
|
|
|
```sh
|
|
$ RecastBuilder test.object
|
|
```
|
|
|
|
And it will create a `test.bin` file, that needs to be copied to the map folder, inside the `Nav/` folder.
|
|
|
|
For example, this would be the structure of files of a Test map:
|
|
|
|
```
|
|
Test/
|
|
├─ Test.umap
|
|
├─ Nav/
|
|
│ └─ Test.bin
|
|
└─ OpenDrive/
|
|
└─ Test.xodr
|
|
```
|