Sketch-based 3D modeling by aligning outlines of an image

In this paper we present an efficient technique for sketch-based 3D modeling using automatically extracted image features. Creating a 3D model often requires a drawing of irregular shapes composed of curved lines as a starting point but it is difficult to hand-draw such lines without introducing awkward bumps and edges along the lines. We propose an automatic alignment of a user's hand-drawn sketch lines to the contour lines of an image, facilitating a considerable level of ease with which the user can carelessly continue sketching while the system intelligently snaps the sketch lines to a background image contour, no longer requiring the strenuous effort and stress of trying to make a perfect line during the modeling task. This interactive technique seamlessly combines the efficiency and perception of the human user with the accuracy of computational power, applied to the domain of 3D modeling where the utmost precision of on-screen drawing has been one of the hurdles of the task hitherto considered a job requiring a highly skilled and careful manipulation by the user. We provide several examples to demonstrate the accuracy and efficiency of the method with which complex shapes were achieved easily and quickly in the interactive outline drawing task. Highlights We present an efficient technique for sketch-based 3D modeling using automatically extracted image features. An automatic and real-time method is proposed to align a user's hand-drawn sketch line to the contour lines of an image, facilitating a considerable level of ease for 3D modeling. We use a geometric method to align a sketch line to the outlines of an image using the features of the sketch line and contour lines of an image, and some operations are proposed to refine the result of alignment. In the sketch-based 3D modeling method, the sketch line is represented by a editable spline, therefore, the aligned sketch line can be further adjusted interactively.

Post Mortem of a Feedwater Heater With Drains Cooler Failures

The Paradise Generation Station Unit 3 is a supercritical fossil plant with a 1,078 MW rated capacity. The #3B feedwater heater (FWH) is a two-zone (condensing and subcooling) horizontal FWH and is the second of four high pressure (HP) FWHs after the boiler feed pump in the “B” string, one of two HP FWH strings (See Figure A2 at the end of this paper for an outline drawing of the heater. The heater has 1447 SA-556-C2 Carbon Steel tubes, 3/4” OD × 0.085 min wall. The heater was built in late 2006/early 2007 and was installed in summer 2007. After just a few years of operation, the #3B FWH experienced several failures at the entrance to the drain cooler (DC) zone. The #3A FWH, of identical construction and built and installed at the same time, did not show the same level of damage. In order to determine the failure mechanisms involved, a post-mortem of the heater was performed. This paper shall discuss the post-mortem inspection conducted as well as the suspected and confirmed causes of failure in the heater.

Frederick Froebel’s philosophies of drawing: Play, representation and invention

This article explores the drawing practice within the educational philosophies of Frederick Froebel. Froebel offers art education and studio practice a great deal of influential approaches, unique media inspirations and enduring philosophical contexts for drawing. Froebel introduced exercises in linear drawing with horizontal and vertical lines, outline drawing of contours, free-hand and nature drawing, circular drawing and drawing from memory. Froebel also suggested more exploratory drawing activities in the service of observing, connecting and evoking form. His approaches towards drawing as varied explorations of nature, contour and shape with unique art media can open up pedagogical possibilities for the rich understanding of form and playful, sensory experiences in contemporary art education.

A Possible Analogy between Contours in Mathematics—As Exemplified by Cauchy's Integral Formula—And Contours in the Arts

An attempt is made to draw an analogy between contour drawing and a particular mathematical theorem. The analogy is seen to depend on the fact that both methods use definite values along a contour to imply a totality of values within the contour; thus, the use of a part to suggest the whole, by way of a hypothetical ‘gestalt-like integration’ in the case of the art contour, and the usual process of mathematical integration in the case of Cauchy's formula. Examples illustrating the analogy are drawn from a wide range of artistic work: a modern American drawing, a Cro-Magnon cave painting, and two Chinese works. The traditional Chinese philosophy of painting is invoked in support of the analogy because of its explicit emphasis on the primacy of outline drawing in Chinese painting. Some speculations are offered on further development and application of the analogy.

A Corinthian Cup and a Euboean Lekythos

In Volume lxix of this Journal I drew attention to three little vases in Reading University belonging to the group published by Wide in AM xxvi (1901) 143 f., at that time regarded as Boeotian and connected by Wide with Mykalessos. They are now known to be Corinthian, since vases and fragments in the same style have been found in the Potters' Quarter at Corinth and are now displayed in Corinth Museum. The general appearance of the vases from this workshop is far removed from that of normal Corinthian, which in the fifth century was decorated largely with floral or linear patterns. When compared with Corinthian red-figure and other vases with outline drawing the childish aspect of many of the figures, their long heavy eyelashes, dimples, chubby limbs, feet with toes on the side facing the spectator, all combine to set them in a field apart. Some of the subjects too are unusual. Among the divinities there is Demeter enthroned with torch, corn and poppies on a plate in Athens; bearded Herakles with club and bow inside cups in Reading and Athens; a youthful Herakles, weary and thirsty, leaning on his club as he fills his cup at a fountain, on a pyxis in the British Museum; Dionysos as Liknites, Winnower, horned and wearing a fawn-skin, holding fork and shovel, on a pyxis in Reading. Among the mortals we find a slinger, a girl playing kottabos and a centaur watching a tortoise inside cups in Athens, London and Leningrad. An unpublished cup in Athens, formerly in the Empedocles collection, shows a warrior advancing with his spear at the ready; another unpublished in Oxford, on loan to the Ashmolean Museum, has Oedipus and the sphinx. The only floral subject that I know is seen in the Reading cup with a rosebud between sprays. There is a replica of this (but with the bud black instead of red) in a cup with a tall foot in Corinth Museum.

Boeotian Haloa

Reading University has recently acquired two fresh examples of the group of small vases with outline drawing first discussed by Wide, who tentatively connected them with Mykalessos. One is a kylix, formerly in the possession of Mr. John Fothergill and most generously presented by him to the University, showing Herakles with his club (Figs, 1 and 2b). The second is a pyxis, damaged somewhat in an air raid of 1945, with a subject on the lid that is less easy to recognise (Figs. 2a and 3). Reading has also a third vase, belonging to this series but standing rather apart from the rest. It is a kylix of the same kind as the first, but decorated inside with a rosebud between sprays (Fig. 4). These three vases with Wide's original five and one other kylix published in the Russian Compte Rendu de la Commission Impériale Archéologique 1901 (1903) p. 131 Fig. 229 (reproduced here in Fig. 5) bring the total of vases of this class up to nine. Nothing is known of the provenance of any of the three vases in Reading and the kylix in Russia is published in a list of chance finds and acquisitions in the government of Cherson with no information as to how it was acquired.Wide associated his group with the cult of Demeter of Mykalessos whose temple, according to Pausanias, was shut every night and opened again by Herakles.

II. —Decorated Initials in English MSS. from A.D. 900 to 1100

A recent beautiful publication by Mr. Mynors of the MSS. in the Cathedral Library at Durham has raised an important point in the history of English illuminated MSS. Up to now there has been a tendency to regard the Norman Conquest as constituting a complete break with the past accompanied by the introduction of a new style of illumination. There is, of course, no doubt that in many spheres of life the Norman occupation of England did do away with many characteristics of Anglo-Saxon England. But this is not the whole story. A change in one department of life does not mean a revolution in another. In the realm of literature, for instance, Professor Chambers has shown that the Conquest did not interrupt the writing and development of vernacular prose. Mr. Mynors's book produces ample evidence to confirm a suspicion long held by some, but not uttered, that much of the ornament used by illuminators of English MSS. during the first fifty years after the Conquest is directly descended from motives in use in England long before the Norman invasion. To Mr. Mynors's evidence from Durham, examples of illuminated MSS. from Canterbury may be added in order to show that the famous outline drawing style of the English MSS. of the tenth and eleventh centuries had healthy descendants in the early years of the twelfth century. The best place to see this continuity is in the illuminated initials of these MSS. In order to do so it is necessary to examine the development of initial ornament in England during the tenth and eleventh centuries.

XII.—The Avian Ulna: Its Quill - Knobs

The presence upon the ulna of many birds of a row of smaller or greater tuberosities, their variety in size and conformation, and the presence of other appearances on the surface of the ulna suggested that an investigation of these variations and of the development of the structures might yield points of interest.Owen (1848) was apparently the first (we have been unable to consult Brandt's paper, quoted by Gadow) to draw attention to these ulnar markings, related to the quills of the secondary remiges. In that year he published a schematic outline drawing of the avian forelimb. Neither in this nor in a subsequent publication (1849), however, did he describe the linear series of markings on the ulna shown in the drawing; but in 1866 he stated that “on the ulnar and anconal sides of the shaft are the rows of quill-knobs (in Raptores) for the secondaries; the anconal row is most marked in longipennate Natatores, and is the only row in many birds.” He mentioned also that this character is wanting in the flightless and some other birds. Pl. I, fig. 1, will be seen to correspond closely with his description.