Here at 360 Panoramas we take 8 pictures in the following pattern. 6 frames taken with the camera facing 10 degrees down from the horizon at 0, 60, 120, 180, 240 and 300 degrees. This slight downward angle closes the nadir (straight down) hole to a small area taken up mostly by the tripod and panoramic head. We then take one picture at about 65 degrees above the horizon. This one captures the whole sky / ceiling area but gets enough of the horizon area in to ensure a good stitch later.
Depending on the ground below you will sometimes need to take a Nadir shot without the tripod for your Virtual Tour. If the ground below is sand or plain carpet or grass it is easy to "clone" the tripod out of the shot later in post processing. however if there is a varying pattern below that canot easily be copied a handheld shot facing straight down trying to keep the camera in as close to the original tripod position and height above ground that the previous virtual tour shots were taken.
You need to keep the focal length, aperture, exposure and iso levels the same for each shot in the virtual tour photo so it helps to have taken a few test meter readings in various directions to get a feel for the exposureceene. Often some amount of comprimise is needed.
Of course you may need to do some clever stuff to keep yourself and your shadow and your reflection out of all the shots. Make use of the timer, a remote shutter release and some hiding spaces
Head over to our website 360 Panoramas | Virtual Tour Photography | Cornwall where there are plenty of Virtual Tour examples and Virtual Tour information. Or why not look at our Virtual Tour and Panorama Gallery for Virtual Tour and Panorama Images from around Cornwall.
in part 3 - stitching and post processing.