Configure grid map environment
==============================

The grid map environment is a 2D grid-based environment that can be used to simulate various scenarios. It can be simply configured by specifying path of image file in the YAML configuration file. 


## Grid Map Configuration Parameters

The python script and YAML configuration file for the grid map environment are shown below:

```python

import irsim

env = irsim.make()

for i in range(1000):

    env.step()
    env.render(0.05)

    if env.done():
        break

env.end()
```

```yaml
world:
  height: 50  
  width: 50  
  obstacle_map: 'cave.png'
  mdownsample: 2

robot:
  - kinematics: {name: 'acker'} 
    shape: {name: 'rectangle', length: 4.6, width: 1.6, wheelbase: 3}
    state: [5, 5, 0, 0]
    goal: [40, 40, 0]
    vel_max: [4, 1]
    plot:
      show_trail: True
      traj_color: 'g'
      show_trajectory: True
      show_goal: False

    sensors: 
      - name: 'lidar2d'
        range_min: 0
        range_max: 20
        angle_range: 3.14
        number: 100
        alpha: 0.4


obstacle:
  - number: 10
    distribution: {name: 'manual'}
    shape:
      - {name: 'polygon', random_shape: true, center_range: [5, 10, 40, 30], avg_radius_range: [0.5, 2]} 

```

The demonstration is shown below:

```{image} gif/grid_map.gif
:alt: Select Parameters
:width: 400px
:align: center
```

### Important Parameters Explained

To configure the grid map environment, the `obstacle_map` in the `world` section should be specified. The `mdownsample` parameter is used to downsample the image for acceleration. The image of `cave.png` should be placed in the same directory as the python script, and is shown below:

```{image} ../cave.png
:alt: Select Parameters
:width: 400px
:align: center
```

In the simulation, this png figure will be rasterized into a grid map. Black pixels represent obstacles, and white pixels represent free space. 

:::{tip}
You can use custom png images to create different grid map environments. The absolute or relative paths can be used to specify the image file in other directories.
:::