Road map planning

If you're truly doing relative sizing it doesn't seem to make sense to translate points to hours. You could potentially look at the average points done and estimate how many Sprints it may take the team to complete the 'as is' Product Backlog or particular features within the road map. 

The other thing I'm reading is that your Product Owner is not empowered and is asking the team to put a square peg in a round hole.

What information are the stakeholders looking to gather by linking hours of work to a 4 month roadmap?

@Tarak 

Agile concept has been used because, the complexity of the projects where requirements are complicated and keep on changing. 

Here the questions is, if requirements are clear and not going to change then why you would need to follow the Agile and you could easily use SDLC modal.

However if Agile is mandatory to be used then I think you can provide high level estimate based on your previous velocity points. 

Thanks

He wants to calculate epic estimation based on personal hours becuase leadership wants it on hour basis

Does he think that is a good reason?

Why is “leadership“ regarding how a Product Backlog is managed and estimated not entrusted to the PO, and team members such as yourself who have concerns over accuracy?

@Tony Divel: Leadership is looking for Personal Hours becuase Hours are directly have direct relation to costs but not with story points.

For leadership, Its all about two points, a. When the feature will deilver b. How many personal hours/days needed to finish this feature 

Is the PO or someone else able to reasonably come up with an average cost per Sprint for the Scrum Team? 

There ought to be a way to simplify the answer to those questions knowing that these are forecasts based on what is known at the time and are likely going to change due to the complex nature of the work. 

here's an  old link / disussion that might help 

https://www.scrum.org/forum/scrum-forum/8360/mapping-story-points-hours