Development of a method for measuring a spectral BRDF at high spatio-temporal resolution

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H04143
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 61010:Perceptual information processing-related
• Research Institution: Osaka Electro-Communication University
• Principal Investigator: Kimachi Akira 大阪電気通信大学, 情報通信工学部, 教授 (30312987)
• Co-Investigator(Kenkyū-buntansha): 土居 元紀 大阪電気通信大学, 情報通信工学部, 准教授 (00304155) ; 西 省吾 大阪電気通信大学, 情報通信工学部, 准教授 (70411478)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 時間相関カメラ / BRDF / 分光画像 / 球面調和関数 / フーリエ係数

Outline of Final Research Achievements

This project aims to develop a method of measuring the spectral BRDF (bidirectional reflectance distribution function, i.e. the distribution of reflectance as a function of wavelength, incident direction, and viewing direction). Its feature is to temporally modulate each approximating component of the object’s spectral BRDF with different frequencies instead of measuring the whole spectral BRDF, and then to extract the components by use of an imaging device called time-domain correlation camera. The temporal modulation is carried out on a programmable spectral light source and a display device for projector use. It is necessary to design and fabricate an ellipsoidal mirror, but the one we fabricated suffered many small defects. Except for this, we were able to establish building components such as the measurement theory, temporal modulation of the illumination, and detection of modulated components of the spectral BRDF by the correlation camera.

Free Research Field

計測工学

Academic Significance and Societal Importance of the Research Achievements

物体表面における光の反射特性はBRDFという関数で記述され，視覚刺激から物体の材質を感じ取る「質感」と深く関わっている．さらに光の波長を考慮した分光BRDFでは，入射方向や視線方向に応じて見かけの色が変化する現象が記述できる．しかし，分光BRDFの計測には角度や波長の分解能と計測時間との間にトレードオフが介在する．本研究の目標はこのトレードオフを解消し，分光BRDFの計測およびそれに基づく画像生成をオンラインで実現して，ディジタルアーカイブやメタバースを介した視覚情報共有などの応用に貢献することである．最終目標にまでは到達できなかったが，それに向けての要素技術は確立することができた．