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光学扫描采集三维头部模型的精度及其对头相关传输函数的影响

Accuracy of three dimensional head model acquired by optical scanning and its effect on the head-related transfer function

  • 摘要: 个性化三维(Three-dimensional, 3D)头部模型在头相关传输函数(Head-Related Transfer Function, HRTF)和虚拟听觉重放(Virtual Auditory Display, VAD)中有着重要应用。光学扫描是获取3D头部模型的常用方法,但不同光学扫描方式的误差及其对HRTF的影响尚不明确。本文以自主设计的3D头部模型为参照模型MO(基准),并将3D打印制作的模型作为扫描对象。选取三款代表性光学扫描设备(手持式红色激光扫描仪HandySCAN 300、手持式白光发光二极管扫描仪Reeyee Pro 2X、红外激光iPhone12手机)扫描得到对应的模型MH,MR和MI。为评价新采集模型曲面精度,对比了模型间图形偏差的色阶图和偏差距离均方根值(Root Mean Square, RMS),进一步分析模型精度对HRTF数据的影响,对比了模型间的HRTF谱误差。结果表明,图形偏差主要集中在耳廓局部细节,HRTF谱误差主要出现在高频。相较而言,模型MH与MO最为接近,曲面误差基本在±0.40 mm以内,超过3.0 dB的HRTF谱误差仅出现在8kHz以上的频段,而这种误差只在少数空间方向中观察到。模型MR和MI相比于MO的曲面误差分别达到约−0.90mm–1.90 mm和−1.20mm–3.20 mm,8kHz以上HRTF谱误差在大多数方向均超过3.0 dB。相关研究为3D头部扫描方式选用提供了参考依据。

     

    Abstract: Personalized three-dimensional (3D) head models have important applications in head-related transfer function (HRTF) and virtual auditory display (VAD). Optical scanning is a common method to obtain 3D head models, but the deviations of different optical scanning methods and their effects on HRTF are not clear. In this paper, the self-designed 3D head model served as a reference model MO (baseline), and the 3D-printed fabricated model was used as the scanning object. Three representative optical scanning devices (handheld red laser scanner HandySCAN 300, handheld white light-emitting diode (LED) scanner Reeyee Pro 2X, and infrared laser iPhone 12 cell phone) were selected to scan and obtain the corresponding models MH, MR, and MI. To evaluate the surface accuracy of the newly acquired models, the color-coded mapping of the graphical deviations between the models and the root mean square (RMS) values of the deviation distances were compared. Further, the HRTF spectral errors between models were compared to analyze the effect of model accuracy on HRTF data. The results showed that the graphical deviations were mainly concentrated in the partial details of the auricle, and the HRTF universal errors mainly appeared in the high frequencies. In comparison, model MH is the closest to MO, with surface errors basically within ±0.40 mm, and HRTF spectral errors exceeding 3.0 dB occur only in the frequency band above 8 kHz, and such errors are observed only in a few spatial directions. The surface errors of the models MR and MI compared to MO reach about −0.90 mm to 1.90 mm and −1.20 mm to 3.20 mm, respectively, and the HRTF spectral errors above 8 kHz exceed 3.0 dB in most directions. The study provides a reference basis for the selection of 3D head scanning modalities.

     

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