Spherical-rod float image velocimetry (SFIV) is a convenient technique combining the positive functions of a rod float velocimetry (RFV) and large-scale particle image velocimetry (LSPIV) for measuring high flow rate in mountain rivers. The SFIV is the principle that the sphere allowing little image distortion according to the orientation is used as a floating tracer for LSPIV. The drifting distances of a spherical-rod float were calculated by geometrical interpretation of spherical images recorded in an experimental open channel and mountain rivers. The depth-reflecting velocities estimated by SFIV in the rivers as in the open channel coincided approximately with the velocities by visual observation from river bank despite of the long shooting distance, weather impact, and flow complicated by topography and bed materials. The velocity coefficients obtained from the experimental channel were used to evaluate depth-averaged velocity for river discharges. The high discharges estimated by SFIV in mountain rivers distributed mostly within the range of the rating curve established by RFV. The results show that the safe and efficient SFIV is a highly applicable technique in mountain rivers with the high flow rate and complex flow. In order to practically use SFIV in mountain rivers, additional studies are required for velocity coefficients depending on the water depth and draft.

球杆浮标测速仪（SFIV）是一种结合杆浮标测速仪（RFV）和大型颗粒图像测速仪（LSPIV）的正函数来测量山区河流高流量的便捷技术。SFIV是这样的原理：根据方向允许几乎没有图像失真的球体被用作LSPIV的浮动示踪剂。通过对实验性明渠和山区河流中记录的球形图像进行几何解释来计算球形杆浮子的漂移距离。尽管开枪距离远，天气影响大，地形和河床材料复杂，但流动距离远，由SFIV估算的明渠在河道中的深度反射速度与河岸的目视速度大致吻合。从实验通道获得的速度系数用于评估河道流量的深度平均速度。SFIV估算的山区河流高流量主要分布在RFV建立的额定曲线范围内。结果表明，安全高效的SFIV是高流速，高流量的山区河流的高度适用技术。为了在山区河流中实际使用SFIV，需要根据水深和吃水深度对速度系数进行其他研究。结果表明，安全高效的SFIV是高流速，高流量的山区河流的高度适用技术。为了在山区河流中实际使用SFIV，需要根据水深和吃水深度对速度系数进行其他研究。结果表明，安全高效的SFIV是高流速，高流量的山区河流的高度适用技术。为了在山区河流中实际使用SFIV，需要根据水深和吃水深度对速度系数进行其他研究。