Imaging acquisition and mapping for fast directional reflectance measurements

Marcos López Martínez; Tim Hartmann; Michael Kremer

doi:10.1117/12.2573495

20 September 2020 Imaging acquisition and mapping for fast directional reflectance measurements

Marcos López Martínez, Tim Hartmann, Michael Kremer

Proceedings Volume 11536, Target and Background Signatures VI; 115360A (2020) https://doi.org/10.1117/12.2573495
Event: SPIE Security + Defence, 2020, Online Only

Abstract

We present an alternative measurement method for BRDF characterization. It is based on imaging instead of angular sampling. Under illumination, the reflectance characteristic of the analyzed material is projected onto a hemispheric diffuse reflective dome surrounding the probe. Images of the dome are taken to capture the directional distribution of the reflected light. This shows the main advantage of the new method: The simultaneous capture of the reflectance within a hemispherical sector, therefore accelerating greatly the data acquisition. However, some additional processing steps have to be implemented to achieve results comparable to the sampling method. Captures with different integration times have to be merged into a high dynamic range (HDR) image and a pixel mapping to absolute scattering angles in spherical coordinates (elevation and azimuth) has to be registered. Measurements acquired with this fist simple approach are quantitatively compared to the aforementioned established sampling acquisition method for two different materials: A diffuse Lambertian reference and a higher gloss degree material. These results are discussed in the last section and will serve as guidelines for future iteration developments of the proposed method.

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Citation Download Citation

Marcos López Martínez, Tim Hartmann, and Michael Kremer "Imaging acquisition and mapping for fast directional reflectance measurements", Proc. SPIE 11536, Target and Background Signatures VI, 115360A (20 September 2020); https://doi.org/10.1117/12.2573495

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