Are Aerial Maps Censored By The Government?

Question

I was looking at "Windows Live" aerial map of Washington D.C.
When looking at key places, I noticed two things.
The White House is visible to the lowest aerial view, but it's obvious that the roof covered over. And when I looked at the capital building, The building and immediate area around it is pixulated.
Is this something that has been done voluntarily or was it mandated by the government for security purposes?

Answer 1

I think it is censored. I was looking at Columbia on Google Earth and most of it was actually blurred out

Answer 2

Yes, it is done to prevent terrorists from using these maps to plot against the US.