METHOD AND APPARATUS FOR MEASURING SURFACE SHAPE

PURPOSE:To achieve that an uneven shape such as a fine groove or the like worked on the surface of a plate material is measured in an on-line manner with good accuracy by a method wherein the cross-sectional shape of an uneven part is measured from the image on the surface of the traveling plate material and from the distance up to the surface of the plate material. CONSTITUTION:The surface of a steel plate 10 which is traveling continuously is image-sensed 12 as a static image in a short time, and the image is stored in an image storage device 18. Simultaneously with an image sensing operation, displacement data (data on an uneven groove) on the surface of the steel plate 10 is sampled by an optical displacement measuring instrument, and a measured value is stored in a data storage device 22. An image processing device 20 processes the still image taken into the device 18, and measures the width of a groove on the surface of the steel plate 10 and the position of an optical spot in the measuring instrument 16 when the still image is sensed. A processing device 24 measures the uneven shape of the groove on the surface of the steel plate from obtained measured values (the width of the groove and the position of the optical spot) and from the displacement data which has been stored 22.