反射式透視投影屏幕應用於擴增實境之散射特性與透視感研究

Scattering Property and Transparency of Reflective See-Through Projection Screen for Augmented Reality Application

李宗達(Tsung-Ta Lee)

指導教授 ： 陳政寰

國立交通大學/電機學院/光電工程系所/碩士(2018年)

摘要

本研究設計之透視投影膜片沿用過去已提出分區獨立投影與透視的概念，藉由設計散射微結構與調整穿透區占比，同時兼具投影效果與透視感達到透明顯示的效果以營造擴增實境的情境設計。透過設計微稜鏡結構來傾斜主散射面並搭配超短焦投影機將主散射光導正回正面觀察者的方向，同時也將穿透區鏡面反射形成的投影眩光（Hot spot）往上偏折以避免眩光造成的視覺不適感。接著於稜鏡結構的主散射面上作雷射加工粗糙處理以消除因稜鏡表面平滑而在投影畫面垂直方向上產生的亮線條紋（glare effect），而透過 BRDF 量測可以得知整體的散射特性，也能量化表面加工對亮線條紋的抑制程度，而整體投影畫面的亮度與過去已量產的橢圓陣列微結構相比也得到提升與驗證。最後透過取得傾斜黑白刀口圖來量測 SFR 以得出近似 MTF 的量測結果，比較兩正交方向黑白對比邊緣的模糊程度差異，其差異程度將隨結構的不對稱性增加而影響整體的透視感。

關鍵字

透視投影顯示 ； 超短焦投影機 ； 擴增實境 ； 雙向反射分布函數 ； 空間頻率響應

並列摘要

A concept of see-through projection film has been proposed, in which the film has only a part of the area being made diffusive and the majority of the area left clearly transparent as the see-through area. For being used with ultra-short throw projector, a micro prism structure is required to make the majority of the diffusively reflected light propagate toward the viewers and separate the glare reflected from the transparent area of the film away from the major viewing direction. The diffusive surface on the micro prism is made with laser processing to resolve the glare effect, which is a bright line orthogonal to the prism direction. In this paper, the bidirectional reflectance distribution function (BRDF) is used as the index for characterizing the scattering property of the film and glare effect. The evaluation of spatial frequency response (SFR) of digital camera is based on the above slanted-edge method, which suits to MTF calculations for spatially sampled capture devices. This paper investigates the relationship between the transparency of the system and different structure of the films based on the SFR.

並列關鍵字

See-through display ； Ultra-short throw projector ； Augmented reality ； BRDF ； SFR

參考文獻

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