Portable three-dimensional metrology with data displayed on the measured surface

Abstract

A portable instrument for 3D surface metrology projects augmented-reality feedback directly on the measured target surface. The instrument generates structured-light measuring-patterns and projects them successively on a target surface. Features, contours, and textures of the target surface distort each projected measuring-pattern image (MPI) from the original measuring-pattern. The instrument photographs each MPI, extracts measurement data from the detected distortions, and derives a result-image from selected aspects of the measurement data. The instrument warps the result-image to compensate for distortions from the projector or surface and projects the result-image on the measured surface, optionally with other information such as summaries, instrument status, menus, and instructions. The instrument is lightweight and rugged. Accurate measurements with hand-held embodiments are made possible by high measurement speed and an optional built-in inertial measurement unit to correct for pose and motion effects.

What is claimed is: 
     
         1 . An apparatus for measuring a surface, the apparatus comprising:
 a hand-held portable housing;   a projection assembly mounted in the hand-held portable housing and projecting an image on the surface;   a camera mounted in the hand-held portable housing and configured to capture the projected image as measurement data; and   a processor controlling the projection assembly and the camera and receiving the measurement data from the camera, where
 the projected image comprises a measurement-pattern image or a result-image; and 
 the processor derives a characteristic of the result-image by analyzing the measurement data corresponding to the measurement-pattern image. 
   
     
     
         2 . The apparatus of  claim 1 , further comprising an inertial measurement unit mounted in the hand-held portable housing and configured to transmit pose and motion data to the processor. 
     
     
         3 . A method for measuring a surface, the method comprising:
 positioning a portable metrology instrument relative to the surface;   projecting one or more measurement-pattern images from the portable metrology instrument onto the surface;   capturing as measurement data one or more captured images of the one or more measurement-pattern images projected on the surface;   creating a point cloud model representing the surface, in which a point in the point cloud model is based on comparing a point in the measurement data with a corresponding point in a stored copy of the one or more measurement-pattern images;   creating a result-image from the point cloud model;   transforming the result-image into coordinates matched to projection conditions on the surface; and   projecting the result-image onto the surface from the portable metrology instrument.   
     
     
         4 . The method of  claim 3 , where the result-image is projected within 0.1 second after the measurement-pattern image. 
     
     
         5 . The method of  claim 3 , where the result-image comprises at least one of a false-color representation of the measurement, a summary of results of the measurement, a symbol dependent on the measurement, an alphanumeric character, a navigational symbol, a status indicator, a menu, and an instruction. 
     
     
         6 . The method of  claim 3 , further comprising monitoring the pose and motion of the portable metrology instrument and doing at least one of:
 issuing a warning if the portable metrology instrument moved in excess of a predetermined threshold during the projecting and capturing of the one or more measurement-pattern images;   storing a location and an orientation of an area of the surface being measured;   adjusting the point cloud model to compensate for the pose and motion of the portable metrology instrument during the projecting and capturing of the measurement-pattern image; and   adapting a feature location and orientation in the result-image to compensate for the pose and motion of the portable metrology instrument during the projecting of the result-image.   
     
     
         7 . The method of  claim 3 , further comprising recording the result-image as projected on the surface. 
     
     
         8 . The method of  claim 3 , further comprising adjusting at least one of color, brightness, and feature position in the result-image to optimize visibility or legibility of the result-image, where the adjusting is partially responsive to a characteristic of the one or more captured images. 
     
     
         9 . An apparatus for measuring a surface, the apparatus comprising:
 a hand-held portable housing;   a projection assembly mounted in the hand-held portable housing and configured for projecting a plurality of images on the surface, including one or more measurement-pattern images and a result image;   a camera mounted in the hand-held portable housing and configured to capture the one or more measurement-pattern images projected on the surface as measurement data; and   a processor controlling the projection assembly and the camera and receiving the measurement data from the camera, where
 the projection assembly comprises an image generator, a light source, and a train of projection optics, and 
 the processor derives a characteristic of the result image by analyzing the measurement data corresponding to the measurement-pattern image. 
   
     
     
         10 . The apparatus of  claim 9 , wherein the projection assembly is configured for projecting the one or more measurement-pattern images and the result image sequentially. 
     
     
         11 . The apparatus of  claim 10 , wherein each of the one or more measurement-pattern images is one of a striped measurement pattern, a periodic-gradient measurement pattern, and a stochastic noise pattern. 
     
     
         12 . The apparatus of  claim 9 , wherein the projection assembly is configured for projecting a series of measurement-pattern images and the result image sequentially. 
     
     
         13 . The apparatus of  claim 12 , wherein each of the series of measurement-pattern images is one of a striped measurement pattern, a periodic-gradient measurement pattern, and a stochastic noise pattern. 
     
     
         14 . The apparatus of  claim 9 , where the image generator comprises one of a liquid-crystal array and a microelectromechanical system. 
     
     
         15 . The apparatus of  claim 9 , where the light source has a variable spectrum controlled by the processor and comprises a light-emitting diode. 
     
     
         16 . The apparatus of  claim 9 , where at least one of the light source, image generator, and train of projection optics are instrumental in projecting both the one or more measurement-pattern images and the result image. 
     
     
         17 . The apparatus of  claim 9 , further comprising an auxiliary light source having a wavelength outside the visible spectrum. 
     
     
         18 . The apparatus of  claim 17 , further comprising at least one of an auxiliary image generator compatible with the auxiliary light source and an auxiliary train of projection optics compatible with the auxiliary light source.