Configuration Configuration of texture images recordings:
Configuration of texture images recordings
Lights OSRAM Tungsten Halogen 64637, 12V, 100W, 3100K
Light Controller Dimmer Osram HT 1-10 DIM,
Transformer Osram HT 150/230/12L
Cameras Sigma SD10, SD9 (c3) Foveon X3 3CMOS, settings: 400 ASA, f14/f11(SD9), Aperture Priority AE, 50cm working distance
Lenses Sigma, 18-200mm f3.5-6.3 DC filtersize 62mm set at 200mm focal length.
Rotation Stage Parker Hannifin Corporation 20505RT
(The rotation table is set up for 800 steps per revolution.
Maximum speed is 5.22 rpm.)
Rotation Stage Controller Parker Hannifin Corporation, power supply P25L,
stepper driver L50, stepper motor SY563T


Viewing Direction:

The textures were placed on a turn table, and recordings were made for aspects of 0, 60, 120, and 180 degrees (conditions -, r60, r120, r180). The last recording is mainly to validate noise robustness for texture analysis algorithms. Four cameras were used, enumerated c1..c4, three perpendicular to the light bow at 0 degrees azimuth and 80, 60, 40 degrees altitude, being c1, c2, c3, respectively. Furthermore, one is mounted at 60 degrees azimuth and 60 degrees altitude, being c4. For the latter camera, aspect is rotated by 60 degrees to have an identical view as camera c2, effectively rotating the illumination bow by 60 degrees.
Combined with five illumination directions and one semi-hemispherical illumination, a sparse sampling of the BTF is obtained.

Illumination Direction:

Each object was recorded with only one out of five lights turned on, yielding five different illumination angles (conditions l1-l5). Furthermore, turning on all lights (condition l8) yields a sort of hemispherical illumination, although restricted to a more narrow illumination sector than true hemisphere.
Note that, for camera c4, the texture was rotated such that the same aspect is viewed as for camera c2. This can be considered as the lighting position being turned 60 degrees towards the camera. Hence, cameras c2 and c4 view the same aspect of the texture, but light direction has shifted by 60 degrees in azimuth. Further note, for camera c1 viewing the material almost perfectly from above, the recordings of the rotated versions of the material correspond to azimuthal rotation of the light source (after correction of the image orientation).

Illumination Color:

Each texture was recorded with 3075K illumination color temperature, at which the cameras were white balanced. One image for each camera is recorded with all lights turned on, at a reddish spectrum of 2175K color temperature (condition i).