Stereo photos
How it was done
One needs two pictures of the same object which are as similar as possible but taken from two different positions. The distance between these camera positions should be roughly a twentieth of the distance to the object.
The photos from the sea were taken within a few seconds, so that the motion of the ship or the aliscafo caused the necessary lateral displacement of the camera. However, the time delay between the two shots is already so long that the volcano's smoke and the surf along the coast are not properly imaged in 3D.
In order to produce 3D-photos of eruptive phenomena it is necessary that the pictures are taken simultaneously. Two motorized single lens reflex cameras were mounted about 12m from each other and released by shutter releases using compressed air.
Making the anaglyphs (red-blue photos)
Each of the image pairs were processed in Adobe Photoshop. As a first step they were reduced from colour to greyscale. Then the left picture was pasted into the red channel of a new RGB image file and the right image into the blue and the green channel of the same RGB image file. Alignment of the two images was achieved by moving and rotating the red channel.
Producing the 3D-contour line map
First the contour lines were digitized in a vector graphics program (Claris Draw). Then the contour lines were sucessively shifted to the left by one pixel with increasing altitude for the left image and to the right for the right image. The blue-red image resulted from a combination of a left (red) and right (blue) map image.
Producing the 3D-crystal drawings
The crystals were drawn by
Erich Offermann (Lettenweg 16, CH-4144 Arlesheim, Switzerland) using the program SHAPE 4.2 by Eric Dowty and Peter Richards. The program can already produce stereo image pairs. The individual images just needed to be coloured and superimposed.
