... serving accurate information ...
I doubt that these information are accurate. There is some truth in it based on what vendors see from honeypots, from installations at customers and from public available data but the vendors don't really see or know everything.
The main point of such threat maps is to make it clear that there is sufficient danger on the internet in order to either sell more security systems or to justify the money already spend for existing installations. This also means that there is no need that these threat maps are fully accurate. They could even make up some data and nobody will really notice since nobody has the full picture.
In order to protect a specific network it is more relevant to detect what attacks target this network and not what kind of attack activity is currently out there in general. Some vendors have threat maps in their products which are based on the traffic directly seen by these installations and thus reflect the attacks against this specific network.
If i launched a big DDOS attack will this attack be visible
It depends on which kind of sources the specific vendor uses. A vendor offering world-wide DDoS protection will likely show it since this is the kind of attacks they fight. But again, the purpose of these threat maps is not to provide an absolutely true picture which include all current attacks.