pab data visualisation

The coordinate system used for self-luminous samples (lamps, LEDs, etc) and for passive reflecting/transmitting samples is basically the same: A standard spherical coordinate system, as shown below.

visualisation of light distribution of lamps and scatter data BSDF

coordinate system

For lamps, LEDs and the like, a direction from the sample is given by two angles ϑ, φ, which defines a standard 3D polar, or spherical coordinate system.
Additionally, we can provide data formatted in the EULUMDAT format.

In case of light scattering, the outgoing direction is given by the same two angles: ϑ_out, φ_out . The incident direction is given by ϑ_in, φ_in. The X-axis, to which φ is measured, should be clearly marked on the sample, even if the material is assumed to be symmetrical before measurements.
This coordinate system has been used by us since the first gonio-photometer in 1989 and is compatible to Standard E2387.
Other coordinate systems can be used if material properties are more easily described with these (e.g. materials with symmetries).

data format

The standard data format consists of ASCII text files with lines:

With the standard detector, the measured signal is proportional to the incident power on the detector, spectrally weighted by detector response and optional filters. With photo-voltaic detectors (e.g. photo-diodes), the units are typically current or, using the characteristics of the detector element, power. For LEDs, the signal is proportional to the radiant intensity [W/sr] emitted from the LED towards the sensor.
For the BSDF, the signal is then scaled by the incident power onto the sample, resulting in absolute BSDF/BRDF data. Units for the BSDF are [1/sr], as usual.
The number of measured points varies between a few hundred and a few hundred thousand points per measurement, depending on the angular resolution. The number of spectral channels depend on the detector configuration.
Additional parameters (incident angle, time, place, machine of measurement, detector settings, etc) are given as comments in the datafile. Comment lines start with ASCII symbol # (hash sign).

Custom data formats can be supplied. Please contact us with your specifications.

mountain visualisation

Our proprietary visualisation tools handle complex data effectively and provide a detailed, interactive view of the measured data sets. They serve to get the maximum information out of measurements and thereby form the essential basis for further analysis of material and lamp characteristics. By providing the function of a looking glass, they ensure the quality and consistency of our measurements.
Please check part II for advanced mountain settings.
The example below consisted of 93138 measured points in the hemisphere.

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