BTFDBB: BTF Database Bonn and Measurement Lab


Spectral Datasets

Here you can download the spectral BTFs acquired during our project on efficient spectral BTF measurements. The data is freely usable for research purposes. Please cite our CGIV paper when using one of the datasets:

Martin Rump, Ralf Sarlette and Reinhard Klein: "externGroundtruth Data for Multispectral Bidirectional Texture Functions", CGIV 2010

General information:
you can access the data either using your web browser and download directly from this page or use our anonymous FTP server:
externftp://btf.cs.uni-bonn.de.

Note:
Some users encountered problems using certain browsers with the provided FTP links. A native FTP client using active-mode will work in these cases.

Documentation:

The BTFs have been measured using our gonioreflectometer setup. Measurement took about 7 days per sample. 
The BTFs are given as a set of registered OpenEXR files. The files are multi-channel where the channel names correspond to the respective wavelength in nm. The file names encode the viewing and lighting angle and are of the following form:

tv<theta_view>_pv<phi_view>_tl<theta_light>_pl<phi_light>.exr

where the theta angles are measured from the normal (0,0,1) and phi angle 0° points towards (1,0,0). The angles are measured in degrees.

The BTFs have been cropped and downsampled to have 300x300 pixel resolution. If you want to access the higher resolution data (800x800) please contact Martin Rump.

Known defects:

  • As only one exposure time per direction pair and spectral band was used, a few images (especially those showing the fresnel effects) suffer from over-exposure.
  • A few images might be not registered with subpixel accuracy since it is very hard to detect the white border around the target at the presence of strong fresnel reflection at shallow angles.
  • If you find any additional defects please contact Martin Rump.

Colorchecker sample

This is a small hand-painted color checker. Besides "standard" paints in different colors also two fluorescent and two metallic paints were used.

Red fabric sample

This is a complex red fabric consisting of four different jarns: two kinds of red, one greenish and one being glossy silver.

Wallpaper sample

A small piece of wallpaper showing lots of interesting effects due to the embossed structure.

Lego Bricks

Some colored Lego bricks including a transparent one showing a lot of parallax, shadowing and interreflections.