&lt;title&gt;Recognition of thick closed polygons in engineering drawing images&lt;/title&gt;

Ablameyko, Sergey; Bereishik, V.; Frantskevich, O.; Homenko, M.; Paramonova, N.

doi:10.1117/12.373487

Cited by 1 publication

(1 citation statement)

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“…8, an attempt is made to combine thick lines, which are not the boundaries of hatched areas, into the contours of closed areas. This operation produces contour lines, from which the filled areas represented by contour boundaries, if there are any, are assembled.…”

Section: Recognition Of Contour Linesmentioning

confidence: 99%

Recognition of Engineering Drawing Entities: Review of Approaches

Ablameyko

Uchida

2007

Int. J. Image Grap.

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Recognition of engineering drawing entities is one of the most difficult stages in engineering drawing interpretation and many attempts to recognize various types of ED entities have been made. In this paper, we review algorithms for the recognition of ED entities, especially dimensions and crosshatching areas. For the recognition of dimensions, we analyze how dimension texts can be separated from graphics and how arrowheads of dimension lines are recognized. We also analyze the recent systems of ED interpretation. Finally, future tasks are discussed. Int. J. Image Grap. 2007.07:709-733. Downloaded from www.worldscientific.com by UNIVERSITY OF CALGARY on 02/05/15. For personal use only. Recognition of Engineering Drawing Entities 711arrowheads are recognized. We review complete or near-complete ED interpretation systems. During the past 20 years, many ED interpretation systems have been developed for automatic or semi-automatic conversion of paper-based EDs to 3D CAD model. Some review material can be found in Refs. 55, 66, 70 and 75. We shall not touch in this paper a character (and other specific symbol) recognition task. There are many papers published for recognition of characters and symbols and we can refer to only several review papers published recently. 12,20,25,49 For editing and 3D reconstruction approaches, which are also omitted here, we can refer to Refs. 9, 10, 13 and 32. ED Entities What are the ED entities?Vectorized ED can be represented in two ways: by graphic primitives or by ED entities. The first representation is rather simple and not always useful. Straight lines, arcs, curves are the most commonly used graphic primitives. They can be grouped for forming more complex primitives, such as chained lines, text blocks, and arrows. Those complex primitives may be further combined into higher-level elements, that is, ED entities such as • contour lines (often represented by solid lines), • symmetry axes (dash-dotted lines), • hidden contour lines (dashed lines), • matter areas (represented by crosshatching), • dimensions (thin lines with arrows, witness lines and so on),• annotation text, and • circles including concentric circles.Examples of some ED entities are shown in Fig. 2.ED entities can be roughly separated into simple and complex ones. Simple ED entities are used for the description for simple ED structures, e.g. a symmetry axis, a crosshatching line, the border of matter area, etc. and can be represented as rather simple combinations of graphic primitives (or their pieces). In Fig. 2. Examples of ED entities; (a) dimension, (b) symmetry axis, (c) crosshatching area, (d) border of crosshatching area, and (e) a set of concentric circles. Among them, (a), (c), and (e) are complex entities and (b) and (d) are simple entities. Int. J. Image Grap. 2007.07:709-733. Downloaded from www.worldscientific.com by UNIVERSITY OF CALGARY on 02/05/15. For personal use only.

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Section: Recognition Of Contour Linesmentioning

confidence: 99%