Is this plot a ParetoFront? and What is the best plot for Pareto Front with >=3 objectives?

I've plotted a Pareto Front (in RED colour) from my NSGA2 Algorithm execution and the result is this for Cost(Y)/Time(X):

In X-Axis: Time in Days In Y-Axis: Cost in Euro

The problem has 3 objectives: time, cost, environmental cost.

Are the gaps in the plot due to multivariable objectives (+3 objectives) in 2D plot ?

Could I plot everything in a 3D plot for a correct visualisation of the Pareto Front?

What is the correct visualization of a multivariable optimization (>3 objectives) for the pareto front? In pairs? Everithing

Thanks in advance.

Generally, when you have only two objectives (bi-objective problem), you can visualize the Pareto front in the objective plane and it is called trade-off curve.

For more than two objectives, techniques developed in statistics such as various diagrams could be used. The other way is to display the bi-objective cross-sections of the Pareto front.

In case, the above mentioned methods do not work efficiently you can use Interactive Decision Maps (IDM) technique

I suggest, you first try to plot a 3D Pareto front and check it out. If it comes out not to be informative enough you can then try other methods. The second method I would try is to plot each couple of objectives as a single plot so for a problem including 3 objectives you need 3 different plots.