Search

Vectorization is the conversion process of a raster image representation into a vector representation. The contemporary commercial vectorization software applications do not provide sufficiently high quality outputs for such images as do mechanical engineering drawings. Line width preservation is one of the problems. There are applications which need to know the line width after vectorization because this line attribute carries the important semantic information for the next 3D model generation. This article describes the algorithm that is able to recover line width of individual lines in the vectorized engineering drawings. Two approaches are proposed, one examines the line width at three points, whereas the second uses a variable number of points depending on the line length. The algorithm is tested on real mechanical engineering drawings.

The contribution deals with the possibilities of the use of existing commercially available vectorization programs for recognition drawing entities in raster graphics format obtained by scanning of the engineering drawing. Drawing entities as a line (solid, dashed, dot-dashed etc.), dimension, hatch, various symbols, text, etc., have specific semantic for the designer defined by standards. Expert knows to interpret this graphic language and he knows to create a mental model of the real object. To be able interpret digital content of the engineering drawing obtained by scanning by the form of 3D computer model often requires to perform many intelligent operations. In the first step it is necessary to obtain such vector representation of the scanned drawing to be able to identify the original drawing entities. Suitability of using the contemporary commercial vectorizing programs for engineering drawings was verified on the test sample of the drawing entities and the results are published in the paper.

The concept of digital manufacturing supposes application of digital technologies in the whole product life cycle. Direct digital manufacturing includes such information technology processes, where products are directly manufactured from 3D CAD model. In digital manufacturing, engineering drawing is replaced by CAD product model. In the contemporary practice, lots of engineering paper-based drawings are still archived. They could be digitalized by scanner and stored to one of the raster graphics format and after that vectorized for interactive editing in the specific software system for technical drawing or for archiving in some of the standard vector graphics file format. The vector format is suitable for 3D model generating, too.The article deals with using of selected integral transformations (Fourier, Hough) in the phase of digitalized raster engineering drawings vectorization.

The concept of digital manufacturing assumes an application of digital technologies in the whole product life cycle. CAD product model replaced engineering drawing in digital manufacturing. In contemporary practice the engineering paper-based drawings are still archived. They could be digitalized and stored to one of the raster graphics format. After that they could be vectorized for interactive editing in the specific software system or for archiving in some of standard vector graphics file format. The vector format is suitable for 3D model generating too. The article deals with using of methods for preprocessing phase of digitalized engineering drawings vectorization process.