Visualization

Visualization messages can be sent to the LCC to draw basic shapes and text in the map view, where the vehicles are shown as well. An example use case for this would be to draw the desired path that a vehicle is supposed to take on command, to check if it actually follows this path. The messages can also be used to show additional information to the running program or simply to debug the sent trajectory by checking the created path visually.

Data structure

The visualization IDL file looks like this:

#include "Color.idl"
#include "Point2D.idl"

enum VisualizationType 
{
    LineStrips=0,
    Polygon,
    StringMessage
};

struct Visualization 
{
    //Id to be able to delete the viz later on
    string id; //@key

    VisualizationType type;
    unsigned long long time_to_live;

    sequence<Point2D> points;
    double size; //Line width in pixels or text size in pt
    string string_message;

    Color color;
};

Each visualization message thus consists of seven data fields which need to be filled accordingly to draw the desired information in the LCC.

ID

Each visualization command is identified by a unique ID. Choose different IDs for commands that should be displayed at the same time, or use the same ID to override an older visualization message.

Visualization Type

Currently, three command types are supported: You can draw a line, a polygon or a string.

Lines and polygons are defined by the points which are set in the structure data as well. In both cases, lines are drawn between subsequent points in the array. The first and the last point are also connected by a line if you want to draw a polygon.

For strings, you need to specifiy a single point where the string is drawn, and you should set the string message that should be displayed.

Time to Live

Each visualization command is removed automatically after a given time. Here, you can set the time to live in nanoseconds.

Points

This field defines the set of points between which lines should be drawn, or the point where the string message should be shown. The coordinate system is the same as the one used for the vehicles.

Points is a custom IDL data type. (see below)

Size

Here you can define the line width or the size of the string message.

String Message

Just set a string for this field (as RTI uses its own string format, be aware that setting this value with a std::string data type might lead to an error message, but give it a try before you use RTI's own implementation).

Color

Lines, polygons and strings can be given any color within the RGB spectrum.

Color is a custom IDL data type. (see below)

Further data structures

struct Point2D {
    double x;    
    double y;    
};

struct Color 
{
    octet a;
    octet r;
    octet g;
    octet b;
};