Masato Sasaki

竹村研究室 修士1年
佐々木 政人


可視光画像を用いたCross-Ratio Method

偏光画像を用いたEye tracking

画像を用いた注視点推定手法は回帰式ベースとモデルベースの2つに大別されるが,それらとは異なる手法としてCross-Ratioベースの手法が提案され,カメラとディスプレイの位置関係を定義するハードウェアキャリブレーションが不要であることから注目を集めている.しかしながら,これらの注視点推定手法の多くは精度の面から近赤外光源と近赤外カメラを用いるのが一般的であり,長時間の近赤外光源の眼への照射は使用者に疲労感をもたらす可能性があるなど,長期の使用には適していない.そこで本研究では可視画像から角膜表面に映るディスプレイ領域を検出し,Cross-Ratio Methodに適用することで,可視画像による高精度の注視点推定を行う.



  1. Masato Sasaki, Takashi Nagamatsu, and Kentaro Takemura, “Screen corner detection using polarization camera for cross-ratio based gaze estimation,” in Proceedings of the 11th ACM Symposium on Eye Tracking Research & Applications (ETRA2019), No. 24, 2019.6.
  2. Masato Sasaki, Takashi Nagamatsu, and Kentaro Takemura, “Cross-Ratio Based Gaze Estimation using Polarization Camera System,” Proceedings of the 2018 ACM International Conference on Interactive Surfaces and Spaces (ISS2018), pp. 333-338, 2018.


  1. 佐々木政人,長松隆,竹村憲太郎:”偏光カメラシステムによるディスプレイ反射領域検出を用いた可視光 Cross-Ratio Method”,ロボティクスメカトロニクス講演会2019,2P1-J03,2019年6月7日,(広島県・広島市)
  2. 佐々木政人,竹村憲太郎:”ディスプレイ反射像を用いた可視光Cross-Ratio Methodによる注視点推定”,ロボティクスメカトロニクス講演会2018,2P1-A06,2018年6月5日,(福岡県・北九州市)


  1. 日本機械学会(学生員)


  1. 平成31年3月25日 東海大学情報理工学部 卒業生総代



  • Cross-Ratio Based Gaze Estimation using Polarization Camera System

In eye-tracking, near-infrared light is often emitted, and at least four LEDs are located at the corners of displays for detecting the screen plane in the cross-ratio based method. However, long-time radiation of near-infrared light can make a user fatigued. Therefore, in this study, we attempted to extract the screen area correctly without near-infrared radiation emission. A polarizing filter is included in the display, and thus, visibility of the screen can be controlled by the light’s polarization direction of the external polarized light filter. We propose gaze estimation based on the cross-ratio method using a developed polarization camera system, which can capture two polarized images of different angles simultaneously. Further, we confirmed that the point-of-gaze could be estimated using the screen reflection detected by computing the differences between two images without near-infrared emission.

  • Screen corner detection using polarization camera for cross-ratio based gaze estimation

Eye tracking, which measures line of sight, is expected to advance as an intuitive and rapid input method for user interfaces, and a cross-ratio based method that calculates the point-of-gaze using homography matrices has attracted attention because it does not require hardware calibration to determine the geometric relationship between an eye camera and a screen. However, this method requires near-infrared (NIR) light-emitting diodes (LEDs) attached to the display in order to detect screen corners. Consequently, LEDs must be installed around the display to estimate the point-of-gaze. Without these requirements, cross-ratio based gaze estimation can be distributed smoothly. Therefore, we propose the use of a polarization camera for detecting the screen area reflected on a corneal surface. The reflection area of display light is easily detected by the polarized image because the light radiated from the display is polarized linearly by the internal polarization filter. With the proposed method, the screen corners can be determined without using NIR LEDs, and the point-of-gaze can be estimated using the detected corners on the corneal surface. We investigated the accuracy of the estimated point-of-gaze based on a cross-ratio method under various illumination and display conditions. Cross-ratio based gaze estimation is expected to be utilized widely in commercial products because the proposed method does not require infrared light sources at display corners.