Last night we finished the job of recording the British Museum’s large Easter Island statue (see here for the first post). As with photogrammetry, the really clever stuff with PTM lies mostly in the software and not the kit. The two most important things here were a shiny little black ball, and a piece of string (the latter was the only thing that gave any grief, when the knots came undone).
James and Hembo took photos for four images of the back, showing separate zones from top to bottom (they finished off the first night by doing this for the hands area at the front). For each one, they set the camera up on a tripod at different heights, from the floor to high on the scaffolding (handy stuff when you’ve got it next door with two nice men to put it all together). Then Hembo took lots of photos while the camera stayed fixed, moving the flash around to alter the lighting angles. The really useful kit here was the wireless trigger that enabled him to fire the camera, which itself tripped the flash. The piece of string ensures the flash is always the same distance from a selected point on the statue, so the light has an even intensity – when the flash was in position, James had to duck out of frame so the shot could be taken. And the black shiny ball reflects back from the flash (creating a specular highlight) so the light direction can be calculated by the software.
Now comes the slow stuff, as we examine the images and work towards a full description of the carvings, and any damage or dressing marks.