(Institute of Electrical and Electronics Engineers, 2014) Flesia, Ana; Ames, Guillermo; Bergues, Guillermo; Canali, Luis; Schurrer, Clemar
External visual interfaces for high precision mea suring devices are based on the segmentation of images of their
measuring reticle. In this paper, a method for subpixel straight
lines detection is presented and tested on images taken from the
reticle of a dark field autocollimator. The method has three steps,
the sharpening of the image using a version of the Savitzky-Golay
filter for smoothing and differentiation, the construction of a
coarse edge image using Sobel filters, and finally, the subpixel edge
location determination, by fitting a Gaussian function to
orthogonal sections of the coarse edge image. We discuss results of
applying the proposed method to images of the reticle of a Nikon
6D autocollimator, using the scale of the device as a benchmark for
testing the error in the location of the lines and comparethem
with Sobel/Hough and Sobel/polynomial fitting. We report that for
this type of image-content, Gaussian fitting has smaller
uncertainty, when cameras with two different sensors are used.
