use the center of the chart as camera direction

Change-Id: I943273817a26235afd9f17e55d2ee14c5f94c409
switch the direction of the series labels

Change-Id: I718ee4782a8b1e265131f6e4e02093a59c17cb15
hardcode default camera height

instead of having the magic number in 5 places

Change-Id: I2550671572dcc36d9a710e56d9d9c1e99f732843
remove unused variables

Change-Id: Ia94a501fa2571752286df0451a0a8a2b303a10c8