271:
other. A diver's digital wristwatch with a depth gauge function is submerged in the box. If the rubber glove is placed on one station and the box with the depth gauge is placed on a lower one, then the hydrostatic pressure between the two points depends only on the difference in heights and the density of the water, i.e. the route of the tube does not affect the pressure in the box. Reading the depth gauge gives the apparent depth change between the higher and lower station. Depth changes are 'apparent' because depth gauges are calibrated for sea water, and the hydrolevel is filled with fresh water. Therefore, a coefficient must be determined to convert apparent depth changes to true depth changes. Adding the readings for consecutive pairs of stations gives the total depth of the cave.
67:
520:
in August 2011, as were the
Paisley Caves Archaeological dig site in SE Oregon. Both were scanned with a FARO Focus Phase shift scanner with +/-2mm accuracy. The Oregon Caves were scanned from the main public entrance to the 110 exit and were loop surveyed to the point of beginning. The data is not yet available for public use, but copies are retained by both the US Park Service and i-TEN Associates in Portland, Oregon.
20:
255:
used, attached to a strip of wood, and the tube is filled with water and the depth at each end marked. In Russia, measuring the depth of caves by hydrolevelling began in the 1970s, and was considered to be the most accurate means of measuring depth despite the difficulties in using the cumbersome equipment of the time. Interest in the method has been revived following the discovery of
471:. If no single error is apparent, one may assume the loop-closure error is due to cumulative inaccuracies, and cave survey software can 'close the loop' by averaging possible errors throughout the loop stations. Loops to test survey accuracy may also be made by surveying across the surface between multiple entrances to the same cave.
494:, which was originally developed by members of the Cambridge University Caving Club for processing survey data from club expeditions to Austria. It was released to the public in 1992. The centerline data can then be exported in various formats and the cave detail drawn in with various other programmes such as
519:
Terrestrial LiDAR units are increasing significantly in accuracy and decreasing in price. Several Caves have been "scanned" using both "time of flight" and "phase shift" LiDAR units. The differences are in the relative accuracies available to each. The Oregon Caves
National Park, was LiDAR scanned
146:
have started to change the process, leading to the advent of fully paperless surveying around 2007. The main variation on the normal methodology detailed below have been devices such as LIDAR and SONAR surveyors that produce a point cloud rather than a series of linked stations. Video-based surveying
474:
The use of a low-frequency cave radio can also verify survey accuracy. A receiving unit on the surface can pinpoint the depth and location of a transmitter in a cave passage by measurement of the geometry of its radio waves. A survey over the surface from the receiver back to the cave entrance forms
117:
was the first person to describe surveying techniques. His surveys were made by having an assistant walk down the passage until they were almost out of sight. Martel would then take a compass bearing to the assistant's light, and measure the distance by pacing up to the assistant. This would equate
270:
The hydrolevel device used in recent
Voronja expeditions comprises a 50-metre (160 ft) transparent tube filled with water, which is coiled or placed on a reel. A rubber glove which acts as a reservoir is placed on one end of the tube, and a metal box with a transparent window is placed on the
254:
Hydrolevelling is an alternative to measuring depth with clinometer and tape that has a long history of use in Russia. The technique is regularly used in building construction for finding two points with the same height, as in levelling a floor. In the simplest case, a tube with both ends open is
486:
There are a large number of surveying packages available on various computer platforms, most of which have been developed by cavers with a basis in computer programming. Many of the packages perform particularly well for specific tasks, and as such many cave surveyors will not solely choose one
463:
to the previous station in the opposite direction. A back-sight compass reading that is different by 180 degrees and a clinometer reading that is the same value but with the reverse direction (positive rather than negative, for example) indicates that the original measurement was accurate.
366:
A Grade 6 survey requires the compass to be used at the limit of possible accuracy, i.e. accurate to ±0.5 °; clinometer readings must be to the same accuracy. Station position error must be less than ±2.5 cm, which will require the use of tripods at all stations or other fixed station
201:
Coincident with recording straight-line data, details of passage dimensions, shape, gradual or sudden changes in elevation, the presence or absence of still or flowing water, the location of notable features and the material on the floor are recorded, often by means of a sketch map.
159:
measurements between stations. The stations are temporary fixed locations chosen chiefly for their ease of access and clear sight along the cave passage. In some cases, survey stations may be permanently marked to create a fixed reference point to which to return at a later date.
740:"HORTA unit for determining the geographic position underground. HORTA-Honeywell Ore Retrieval and Tunneling Aid-is a box containing a gyro and an accelerometer, originally developed for the U.S. military, that solves the problem of positioning and location underground."
105:. It consists of an elevational section of the cave. Numerous other surveys of caves were made in the following years, though most are sketches and are limited in accuracy. The first cave that is likely to have been accurately surveyed with instruments is the
380:
Grade X is only potentially more accurate than Grade 6. It should never be forgotten that the theodolite/Total
Station is a complex precision instrument that requires considerable training and regular practice if serious errors are not to be made through its
458:
Despite these advances, faulty instruments, imprecise measurements, recording errors or other factors may still result in an inaccurate survey, and these errors are often difficult to detect. Some cave surveyors measure each station twice, recording a
510:
have full centerline and map editing capabilities. Therion notably, when it closes survey loops, warps the passages to fit over their length, meaning that entire passages do not have to be redrawn. Unlike
Therion's 2D warping capabilities,
141:
methodology, but most are based on a similar set of steps which haven't changed fundamentally in 250 years, although the instruments (compass and tape) have become smaller and more accurate. Since the late 1990s, digital instruments such as
454:
The equipment used to undertake a cave survey continues to improve. The use of computers, inertia systems, and electronic distance finders has been proposed, but few practical underground applications have evolved at present.
515:
warps passages in 3D. This includes warping plan and profile sketches. CaveWhere also supports loop closure (using Survex) and provides a user friendly interface for entering and visualizing cave survey data.
377:
Caving organisations, etc., are encouraged to reproduce Table 1 and Table 2 in their own publications; permission is not required from BCRA to do so, but the tables must not be reprinted without these notes.
370:
A Grade X survey must include on the drawing notes descriptions of the instruments and techniques used, together with an estimate of the probable accuracy of the survey compared with Grade 3, 5 or 6 surveys.
373:
Grades 2 and 4 are for use only when, at some stage of the survey, physical conditions have prevented the survey from attaining all the requirements for the next higher grade and it is not practical to
328:
A Magnetic survey. Horizontal and vertical angles measured to ±1 °; distances should be observed and recorded to the nearest centimetre and station positions identified to less than 10 cm.
363:
To attain Grade 5 it is essential for instruments to be properly calibrated, and all measurements must be taken from a point within a 10 cm diameter sphere centred on the survey station.
478:
In the past, cavers were reluctant to redraw complex cave maps after detecting survey errors. Today, computer cartography can automatically redraw cave maps after data has been corrected.
467:
When a loop within a cave is surveyed back to its starting point, the resulting line-plot should also form a closed loop. Any gap between the first and last stations is called a
54:
Traditionally, cave surveys are produced in two-dimensional form due to the confines of print, but given the three-dimensional environment inside a cave, modern techniques using
354:
The above table is a summary, omitting some technical details and definitions; the definitions of the survey grades given above must be read in conjunction with these notes.
316:
A rough magnetic survey. Horizontal & vertical angles measured to ±2.5 °; distances measured to ±50 cm; station position error less than 50 cm.
39:
system, which may be produced to meet differing standards of accuracy depending on the cave conditions and equipment available underground. Cave surveying and
555:
Such automated methods have provided a more than fifty-fold increase in underground surveying productivity with more accurate and finer detail maps as well.
106:
43:, i.e. the creation of an accurate, detailed map, is one of the most common technical activities undertaken within a cave and is a fundamental part of
322:
May be used, if necessary, to describe a survey that fails to attain all the requirements of Grade 5 but is more accurate than a Grade 3 survey.
143:
512:
230:
The cartographer then draws details around the line-plot, using the additional data of passage dimensions, water flow and floor/wall
731:
78:
The first known plan of a cave dates from 1546, and was of a man-made cavern in tufa called the Stufe di Nerone (Nero's Oven) in
384:
In drawing up, the survey co-ordinates must be calculated and not hand-drawn with scale rule and protractor to obtain Grade 5.
605:
234:
recorded at the time, to produce a completed cave survey. Cave surveys drawn on paper are often presented in two-dimensional
708:
415:
Measurements of detail made at survey stations and wherever else needed to show significant changes in passage dimensions.
283:, of a cave survey is dependent on the methodology of measurement. A common survey grading system is that created by the
812:
687:
655:
284:
1201:
793:
242:
views, while computer surveys may simulate three dimensions. Although primarily designed to be functional, some
129:
in 1964. The software was programmed onto a large university mainframe computer and a paper plot was produced.
1254:
51:, provide a spatial reference for other areas of scientific study and assist visitors with route-finding.
310:
May be used, if necessary, to describe a sketch that is intermediate in accuracy between Grade 1 & 3
537:
155:
A survey team begins at a fixed point (such as the cave entrance) and measures a series of consecutive
47:. Surveys can be used to compare caves to each other by length, depth and volume, may reveal clues on
895:
1230:
1191:
114:
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1223:
475:
an artificial loop with the underground survey, whose loop-closure error can then be determined.
1269:
1264:
1048:
1237:
576:
55:
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In all cases it is necessary to follow the spirit of the definition and not just the letter.
360:
To attain Grade 3 it is necessary to use a clinometer in passages having appreciable slope.
172:
121:
The first cave to have its centreline calculated by a computer is the Fergus River Cave in
66:
8:
1259:
786:
214:
analyzes the recorded data, converting them into two-dimensional measurements by way of
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1308:
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863:
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113:. This was surveyed by a civil engineer in 1765 and includes numerous cross-sections.
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71:
621:
Nicholson, F.H.; Patmore, D.J. (1965). "The Fergus River Cave, Co. Clare, Ireland".
1038:
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Normally only one of the following combinations of survey grades should be used:
58:
are increasingly used to allow a more realistic representation of a cave system.
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The accuracy of the detail should be similar to the accuracy of the line.
98:
40:
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In recent years an underground geographic positioning technology called
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optionally, distance to surrounding walls – left, right, up, down (
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643:
Degtjarev, Alexander; Snetkov, Eugene; Gurjanov, Alexey (July 2007).
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222:; a scaled geometrical representation of the path through the cave.
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A magnetic survey that is more accurate than grade 5, (see note 5).
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or total station instead of a compass, (see notes 6 and 10 below).
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Another early survey dates from before 1680, and was made by
802:
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Sketch of low accuracy where no measurements have been made
126:
36:
633:
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32:
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762:, the official journal of the BCRA Cave Surveying Group
490:
A popular program for producing a centerline survey is
295:
573: – Recreational pastime of exploring cave systems
86:
in Italy. The first natural cave to be mapped was the
163:
The measurements taken between the stations include:
409:
Measurements of detail made at survey stations only.
403:
Passage details estimated and recorded in the cave.
267: – currently the world's second deepest cave.
645:"Obtaining accurate cave depths by hydrolevelling"
487:product over another for all cartographic tasks.
340:A survey that is based primarily on the use of a
1295:
620:
287:in the 1960s, which uses a scale of six grades.
389:BCRA gradings for recording cave passage detail
181:inclination from horizontal (dip) taken with a
787:
187:distance measured with a low-stretch tape or
319:Grade 4 (use only if necessary, see note 7)
307:Grade 2 (use only if necessary, see note 7)
794:
780:
768:, A collection of Surveys of British Caves
706:
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598:An Encyclopedia of Caves and Karst Science
727:
725:
716:16th International Congress of Speleology
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218:calculations. From them he/she creates a
506:. Other programmes such as 'Tunnel' and
94:, of which a sketch from 1656 survives.
65:
18:
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722:
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246:consider cave surveys as an art form.
205:
125:, which was plotted by members of the
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755:Laser Scanning History: Paisley Caves
481:
118:to a modern-day BCRA Grade 2 survey.
709:"Quick 3D Cave maps using Cavewhere"
595:
567: – Diving in water-filled caves
523:
397:All passage details based on memory.
296:BCRA gradings for a cave line survey
738:, April 2000, accessed 2010-12-02.
16:Map of all or part of a cave system
13:
14:
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813:Glossary of caving and speleology
748:
688:British Cave Research Association
285:British Cave Research Association
249:
1202:Nok and Mamproug Cave Dwellings
801:
147:also exists in prototype form.
74:by the Yorkshire Ramblers' Club
614:
589:
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1:
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137:There are many variations to
1255:List of UK caving fatalities
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7:
707:Schuchardt, Philip (2013).
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538:inertial navigation system
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658:Cave Survey Group: 8–12.
552:-position determination.
532:has been utilized in the
1231:Cave of Forgotten Dreams
348:
1224:Diving into the Unknown
736:Canadian Mining Journal
684:"BCRA Surveying Grades"
1270:Tham Luang cave rescue
1265:Riesending cave rescue
540:technology utilizes a
450:Survey error detection
367:markers ("roofhooks").
75:
24:
1238:The Underground Eiger
577:List of longest caves
115:Édouard-Alfred Martel
69:
56:computer aided design
22:
766:CaveMaps.org Surveys
101:of Long Hole in the
35:of all or part of a
1260:Alpazat cave rescue
905:Types and formation
291:BCRA grading system
206:Drawing a line-plot
1187:Cave-dwelling Jews
934:Estavelle/Inversac
732:Inco's Innovations
482:Surveying software
469:loop-closure error
107:Grotte de Miremont
76:
25:
1291:
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1069:(Cave formations)
832:Cave conservation
607:978-1-57958-399-6
596:Gunn, J. (2003).
524:Automated methods
500:Adobe Illustrator
279:The accuracy, or
189:laser rangefinder
72:Marble Arch Caves
1321:
914:Anchihaline cave
896:Caves by country
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70:1908 survey of
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23:A cave survey
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1229:
1222:
1182:Cave dweller
1096:Cave popcorn
1035:Underground
954:Karst spring
944:Glacier cave
841:
739:
735:
715:
702:
691:. Retrieved
678:
667:. Retrieved
651:
626:
622:
616:
597:
591:
554:
527:
518:
489:
485:
477:
473:
468:
466:
460:
457:
453:
280:
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269:
253:
239:
235:
229:
219:
212:cartographer
209:
200:
194:
162:
154:
136:
120:
96:
77:
53:
28:
26:
1061:Speleothems
974:Exploration
874:Troglofauna
842:Cave survey
820:Main topics
565:Cave diving
216:geometrical
210:Later, the
167:direction (
144:distometers
133:Methodology
99:John Aubrey
41:cartography
29:cave survey
1298:Categories
1197:Kome Caves
1161:Stalagnate
1156:Stalagmite
1151:Stalactite
1141:Soda straw
1131:Shelfstone
1091:Cave pearl
1066:Speleogens
1031:Talus cave
964:Ley tunnel
891:Speleology
869:Stygofauna
693:2009-05-02
669:2009-05-02
583:References
548:to aid in
461:back-sight
374:re-survey.
342:theodolite
232:topography
226:Finalising
183:clinometer
45:speleology
1314:Map types
1309:Surveying
1248:Incidents
1175:Dwellings
1116:Helictite
1111:Frostwork
1106:Flowstone
1076:Anthodite
1049:Waterfall
1021:Suffosion
1006:Show cave
991:Salt cave
959:Lava cave
907:processes
857:Equipment
664:1361-8962
629:(3): 285.
542:gyroscope
513:CaveWhere
220:line-plot
151:Surveying
139:surveying
1283:Category
1136:Snottite
1126:Rimstone
1121:Moonmilk
1011:Sinkhole
996:Sea cave
981:Pit cave
949:Ice cave
559:See also
504:Inkscape
437:5C or 5D
434:3B or 3C
275:Accuracy
265:Caucasus
80:Pozzuoli
1207:Yaodong
1081:Boxwork
924:Cave-in
544:and an
508:Therion
496:AutoCAD
412:Class D
406:Class C
400:Class B
394:Class A
337:Grade X
331:Grade 6
325:Grade 5
313:Grade 3
301:Grade 1
263:in the
259:on the
257:Voronja
240:profile
238:and/or
177:compass
173:bearing
169:azimuth
123:Ireland
92:Germany
62:History
1016:Spring
929:Cenote
852:Diving
847:Caving
805:topics
662:
654:(38).
604:
571:Caving
534:mining
492:Survex
244:cavers
111:France
84:Naples
1044:River
986:Ponor
939:Foiba
881:Karst
864:Fauna
712:(PDF)
648:(PDF)
530:HORTA
420:Notes
349:Notes
281:grade
82:near
31:is a
1064:and
1039:Lake
1026:Sump
969:Mine
803:Cave
660:ISSN
656:BCRA
602:ISBN
502:and
381:use!
236:plan
195:LRUD
127:UBSS
37:cave
1166:Vug
171:or
109:in
90:in
33:map
1300::
734:,
724:^
714:.
686:.
650:.
635:^
627:10
625:.
550:3D
498:,
440:6D
431:1A
27:A
795:e
788:t
781:v
718:.
696:.
672:.
610:.
197:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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