Update README.md

README.md

@@ -46,6 +46,7 @@ To generate new road images, follow the next steps:
  
 <img align="center" src="docs/images/ppi_conv.gif" alt="Equation to compute the required ppi of the image" width="201" height="42">
 
+* If you want to generate a scaled version of the orginal road, in the previous equation, use the road size from the YAML file scaled by the desired value. For example, if we want to create a 1:8 scale road, divide by 8 the actual road size.
 * To change the ppi of the original image, execute the following command (both the original and modified images must be PNG):
 ```
 convert <original_image> -density <new_ppi_value> -units PixelsPerInch <modified_image>
@@ -62,8 +63,8 @@ This package file includes a launch file named spawn_road.launch which is intend
 * **road_name**: (default=road) name of the road image to be used (without the .png extension). This name will also be used to name the nodes and topics associated with the road description.
 * **road_size**: (default=15.0) size of the road in meters. At the moment only square road images are supported. This value can be taken from the YAML file.
 * **road_path**: (default=$(env HOME)/Downloads) path where the road image is located. It must be and absolute path.
-* **x** (default=0.0) x position where the road will placed in the simulated environment with respect to the parent frame. This value can be taken from the YAML file.
-* **y** (default=0.0) y position where the road will placed in the simulated environment with respect to the parent frame. This value can be taken from the YAML file.
+* **x** (default=0.0) x position where the road will placed in the simulated environment with respect to the parent frame. This value can be taken from the YAML file. If you generated a scaled version of the original road, divide the YAML file value by the scale factor.
+* **y** (default=0.0) y position where the road will placed in the simulated environment with respect to the parent frame. This value can be taken from the YAML file. If you generated a scaled version of the original road, divide the YAML file value by the scale factor.
 * **yaw** (default=0.0) orientation of the road with respect to the parent frame. This value should normally be 1.5707 radians.
 * **parent** (default=map) parent reference frame used to place the road in the simulated environment.