Stone Polygons Research Articles

WALL STONE EXTRACTION BASED ON STACKED CONDITIONAL GAN AND MULTISCALE IMAGE SEGMENTATION

Abstract. The historical castles (castellated walls), which are cultural heritages in Japan, require regular maintenance, and it is necessary to record the arrangement of individual wall stones in the maintenance work. Recently, image processing techniques are practiced to optimize maintenance and management of the infrastructure assets. In the previous study, we proposed an automatic method for efficiently extracting individual wall stone polygons by improved multiscale image segmentation technique. However, the problem has remained that wall stone polygons could not be extracted properly when there were no clear gaps or boundaries between stones. To address this problem, we improved the multiscale image segmentation technique used in our previous studies. The first improvement is that in the region growing process, selecting the best combination of a plurality of objects instead of two. The second improvement is the modification of the shape criterion to be used. Besides, we proposed three-stage Stacked cGAN for wall stone edge detection that enables us to complement areas with weak or broken boundaries of stone edges. This approach is composed of a coarse-to-fine based image-to-edges translation network. The edge images derived from this method are used as the additional channel in multiscale image segmentation with a higher weight compared to the other RGB channels. It was confirmed that the separation performance of individual wall stone polygons was improved by the proposed method. Furthermore, the proposed method is highly effective to reduce the difficulty in setting of the scale parameter, which is usually sensitive to segmentation results and requires trial and error.

EXTENDED MULTISCALE IMAGE SEGMENTATION FOR CASTELLATED WALL MANAGEMENT

Abstract. Castellated walls are positioned as tangible cultural heritage, which require regular maintenance to preserve their original state. For the demolition and repair work of the castellated wall, it is necessary to identify the individual stones constituting the wall. However, conventional approaches using laser scanning or integrated circuits (IC) tags were very time-consuming and cumbersome. Therefore, we herein propose an efficient approach for castellated wall management based on an extended multiscale image segmentation technique. In this approach, individual stone polygons are extracted from the castellated wall image and are associated with a stone management database. First, to improve the performance of the extraction of individual stone polygons having a convex shape, we developed a new shape criterion named convex hull fitness in the image segmentation process and confirmed its effectiveness. Next, we discussed the stone management database and its beneficial utilization in the repair work of castellated walls. Subsequently, we proposed irregular-shape indexes that are helpful for evaluating the stone shape and the stability of the stone arrangement state in castellated walls. Finally, we demonstrated an application of the proposed method for a typical castellated wall in Japan. Consequently, we confirmed that the stone polygons can be extracted with an acceptable level. Further, the condition of the shapes and the layout of the stones could be visually judged with the proposed irregular-shape indexes.

Writings of the talented Russian geomorphologist I.N. Gladtsyn

I.N. Gladtsyn was talented representative of the first generation of Russian geomorphologists, first-rate organizer, the teacher of such outstanding scientists as I.P. Gerasimov, K.K. Markov, S.S. Schults. He performed field researches in the Transbaikalia, the Kolsky Peninsular, the Crimea; in his writings regional investigations were predominant. His main topics were rock glaciers, stone polygons, origin and dynamics of the salt Transbaikalian lakes, origin and structure of the Crimean red-beds. I.N. Gladtsyn is the author of the first in this country text-book Relief of the USSR (1939).

Further examples of ventifacts and unusual patterned ground from the falkland islands, south atlantic

Examples of ventifacts and forms of unusual patterned ground that differ in situation, characteristics and/or origin to types reported previously are described from the Falkland Islands, South Atlantic. The ventifacts, represented by clasts projecting from an eroding tillite shore platform, have been grooved by the passage of windblown sand. The patterned ground forms comprise stone polygons on clay loam regolith, stone polygons on peat, peat‐filled desiccation cracks on peat, and clusters of on‐edge clasts (stone packings) on a gravel beach. Aeolian transport of particles is considered responsible for the infill of the polygonal cracks. The clusters of on‐edge clasts are thought to have developed as a result of wave action, in particular backwash and/or undertow. Although these features occupy small surface areas they provide useful information about local geomorphic processes and testify to the marked diversity of such features in nature.

Forms of Unusual Patterned Ground: Examples from the Falkland Islands, South Atlantic

Three forms of unusual patterned ground are described from the Falkland Islands, South Atlantic. 1. Stone polygons have developed on residual peat following clast transport from adjacent exposures of angular rock debris, desiccation of the peat surface and reworking of clasts into the network of open cracks.2. In areas of abundant sand supply, sand polygons are present on lake-bed and lake-margin peat surfaces that have experienced desiccation. Sections through these polygons reveal sand-filled cracks reaching 25 cm in depth.3. The movement of sheep and cattle across erosion scars has created numerous hoof-print depressions which have become filled with small stones and now form roughly circular to irregular stone-filled hoof prints.These features do not result from frost-related processes and appear not to have been recorded in other regions. The exact mechanisms by which clasts and sand have been transported are not known with certainty although aeolian action, sheetflow, and wind-generated wave...

Present‐day periglacial microforms in the Lesotho Highlands: Implications for present and past climatic conditions

AbstractA variety of active periglacial microforms have been identified in the vicinity of Tlaeeng Pass (3275 m a.s.l.) in the Lesotho Highlands. These include thufa (both earth and stone‐cored varieties), terracettes, stone polygons and patterned ground. Ground ice within the saturated zone of soil profiles is clearly evident during the winter season, and pebbles perched on needle ice up to 5 cm in length are common. Although possible relict periglacial landforms (such as nivation hollows and protalus ramparts) have been recorded in the area, their identification and, hence, associated climatic inferences is problematic.The presence of active features clearly indicates present‐day periglacial activity, with the variety of forms resulting from diurnal or seasonal freeze‐thaw cycles. Considering a widely accepted global decrease in temperature during the Quaternary, a severity of temperatures greater than what is experienced under present marginal periglacial conditions can be projected for the Lesotho Highlands. However, past moisture regimes are more difficult to project from present‐day features, and this problem is exacerbated by the general paucity of clearly defined diagnostic relict forms.

Large Sorted Stone Polygons, and Ventifact Distribution, in the Syrkadal Area, Scania, S. Sweden

Large sorted polygons in Syrkadal Valley, SE Scania, S Sweden are described (UTM Grid Reference VB 615940 045610). A total number of 18 polygons are identified. Their mean size is 5.9 meters. Most stones and boulders in the vicinity are ventifacted whereas practically no polygon boulders are ventifacted. Both the polygons and the ventifacts are relict periglacial features. The polygons are interpreted as post-dating the ventifacts of the area, and probably formed during the time span from the deglaciation to the end of Older Dryas (12 050 BP). They were probably reactivated during the earlier part of Younger Dryas (11 000–10 500 BP). The wind action during Younger Dryas in the Syrkadal-Bäckhalladalen area is interpreted as insufficient for ventifact formation. Factors contributing to the destruction or preservation of relict sorted polygons are discussed.

Large Sorted Stone Polygons, and Ventifact Distribution, in the Syrkadal Area, Scania, S. Sweden

Large Sorted Stone Polygons, and Ventifact Distribution, in the Syrkadal Area, Scania, S. Sweden

Beobachtungen an rezenten und fossilen (kaltzeitlichen) Strukturböden

The shape and structure of stone rings and polygons on level ground and of the stone strips on slopes correspond closely in Spitzbergen and the Alps. Moreover, in both areas the frostsoil or permafrost, which must have remained frozen for several years at a time, undergoes the same changes at the surface during the annual thaw: it is always the pocket of finer soil or, in the case of sloping ground, the deposit of soil between the stone strips which thaws first. Figure 6 shows how, in an alpine stone strip rock structure, the level of the frostsoil sinks in the course of summer and rises again in late summer and early autumn.

Permafrost in England during the Last Glacial Period

PERMAFROST has been shown by many authors to have existed in various parts of England during the last glacial period1,2. Its full extent and distribution have remained somewhat uncertain but can be deduced from the occurrence of certain fossil ground structures. Ice-wedge polygons, the trough patterns of chalkland2, and the largest stone polygons and stripes are generally accepted as requiring permafrost. Less reliable features are involutions, and a deep layer of upturned stones above horizontally-bedded gravels. Preliminary results are reported here from mapping these structures using pit sections and air photographs.

Stability of Stone Polygons in North Wales

THIS communication describes certain preliminary observations made on stone polygons in Snowdonia during the summer of 1957, observations which appear to reveal the impermanent character of these structures. The polygon area has been briefly described by Pearsall1; it consists of several connected flat expanses of bare detritus, formed from the erosion of the Juncetum squarrosi occupying the broad ridge between Carnedd Llywelyn and Foel Grach summits in the Carneddau at 915–945 m. The area was casually examined several times during the summer of 1956, but no polygons were observed, the detritus being unsorted. In the course of field work during the first week of July 1957 well-defined stone polygons were noticed over the whole area (Fig. 1); each polygon was 45–60 cm. in diameter, with a centre of fine gravelly detritus and a rim, 10–15 cm. wide, of coarse stone (3–10 cm.); these coarse stones extended downwards for 10–15 cm., finally merging into a matrix continuous with the polygon centres. Ten days later, after predominantly fine weather but with a few days of rain with a blustery north-east wind, it was noticed that a large proportion of the polygons had, by apparent obliteration of the cross-connexions, been converted into stone stripes 2–4 m. long, orientated more or less at right angles to the direction of the prevailing wind (Fig. 2). For much of the remainder of July 1957 the weather was wet, with more or less permanent low cloud. On July 15 there was little change in the polygons. On July 30, however, after a fortnight of heavy rain and strong winds, a large number of the polygons and stripes had been obliterated or were in process of obliteration. On September 3 one of the areas was almost completely unsorted, and many of the stripes on the other areas were indistinct. Polygons were very rare, and the stripes had markedly elongated, extending for many metres without interruption. In July 1958, the next opportunity for a further examination, the area exhibited little change, except qualitatively in that the stone stripes appeared far less elongated.

Anchored stone polygons at low levels within the Icelandic basalt regions

Anchored stone polygons at low levels within the Icelandic basalt regions

Polygon nets and their physical development

Freezing forces suffice in explaining stone rings but swelling may aid the process. Measurements of many stone polygons show that most of them are made up of more or less equilateral hexagons.

Stone-Centered Polygons

Upended shale fragments as herein described form a pattern resembling the stone polygons of arctic and alpine regions. Unlike most northern occurrences, these fragments lie on bedrock, and clay is practically absent.

Stone Polygons beside Loch Lomond

STONE polygons are polygonally arranged bands of flat pebbles, usually surrounding a core of mud, common in Arctic regions in soils composed of mud and stones. They may be associated with curved arcs of stones, each of which is also standing on end. These structures are well known in Spitsbergen, Norway, Iceland*, and Antarctica, and have been found in the Alps. Their formation has been discussed in a long and scattered literature. The chief theories of their formation have been clearly summarized in a paper by Professor J. S. Huxley and Dr. N. E. Odell, in this Journal (vol. 63,1924, pp. 207-229). The most widely accepted explanation attributes these struc? tures to the repeated outward push of the pebbles whenever the ground is frozen, and the flow back of the mud during thaw. That theory was advanced by Professor Hogbom (Bull. Geol. Inst. Upsala, ix, 1908, pp. 41-59) and has been widely adopted, as by Professor Hawkes for a case on a raised beach in Iceland (GeoL Mag., 1924, pp. 509-513, pl 28)and by Dr. C. S. Elton (Q.J.G.S., vol. 83,1927, pp. 163-193, pl. 10-12), Nansen (En Ferd til Spits? bergen, 1920 ; Spitsbergen, 1921) on the other hand regarded the polygons as due not to the migration of the pebbles but to the reduction to powder of those in the centre of a group by repeated freezing. This comminution of the stones no doubt takes place to some extent when they consist of soft shale; and both processes are regarded by Huxley and Odell as having shared in the formation of these structures. A modification of the frost-push theory has been advanced by Thoroddsen for the examples in Iceland, where they are known as rudemarks. His account of the phenomenon, although one of the earliest, has been often overlooked (Thoroddsen, 'The Botany of Iceland,' Pt. I. Physical Geography, 1914, pp. 259-261). He attributed these structures to the combined effect of irregular evaporation from sodden stony clay which has been cracked by frost into clay prisms, and of the pebbles being pushed by repeated frost and thaw into the shrinkage cracks. My interest in these formations was arowsed the day Sir Martin Conway's expedition landed at Green Harbour, Spitsbergen, on 18 June 1896. From the observations made there and at other places in Spitsbergen Professor Garwood and I concluded that these polygons were due to the repeated freezing and thawing of the ground. The stone hexagons appear due to the water freezing into large ice crystals charged with mud and stones, like the sand-charged calcite of the Fontainebleau Sandstone. We did not describe the structures as we expected to find examples of them in the English boulder clays; but to my repeated surprise I have failed to find them in the British glacial drifts, and I am not aware of any definite case of them having been described in glacial deposits, though vertical stones in such are not nixconftnion. Embryonic frost-formed stone polygons I have frequently observed in recent deposits in Scottish valleys, and I have occasionally seen them well dbveJoped, as on the summit of the Merrick (2764 feet), the highest summit in Scotland south of the Highknds (as remarked Q.J.GJS., vol. 83,1927, p. 193), and on Ben Lawers.