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< title > CUCC Expo Surveying Handbook: Laser points< / title >
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< h2 id = "tophead" > CUCC Expo Surveying Handbook< / h2 >
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< h1 > Geographical fixed points on Loser< / h1 >
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< h3 > Note to readers in the 2020s< / h3 >
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< figure class = "onright" >
< a href = '/handbook/survey/l/orthoheight.html' > < img width = 25% src = '/handbook/survey/i/orthoheight.jpg' / > < / a > < figcaption style = "text-align: left" > Click for explanation< / figcaption > < / figure >
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< p > While this page is mostly < em > correct< / em > , it is most definitely not < em > current< / em > .
It was written in 2001 and last seriously updated in 2006.
These days the Austrians use WGS84 GPS like eveyone else.
< p > For the nitty gritty about coordinate systems in Austria see:< br >
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< a href = "/stations" > Troggle report: UTM/G& K entrance data< / a > < br >
< a href = "/entrances" > Troggle report: entrances< / a > < br > < br / >
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< a href = "coord2.html" > GPS and coordinate systems< / a > < br >
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< a href = "coord.htm" > Basic Coordinate Systems< / a > .< br >
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< a href = "lasers.htm" > Geographical fixed points on Loser< / a > < br >
< a href = "/katast.htm" > The Austrian Kataster areas< / a > < br / >
< a href = "https://hoehle.org/downloads/SD_10_Handbuch.pdf" > SD 10 Handbook: Vergleich der Ö K 50 mit der neuen Ö K 50-UTM< / a > < br >
< a href = "https://www.cavinguk.co.uk/info/locatingsurveys.html" > Location fixing: How to obtain a fixed point for a cave survey< / a >
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< p > From Patrick Warren (< a href = "https://github.com/patrickbwarren/qgis3-survex-import" > qgis3-survex-import< / a > ):< br / >
"Many of the cave entrances are
recorded using a truncated form of the MGI / Gauss-Krüger (GK) Central Austria
CRS (the non-truncated form is
< a href = "https://spatialreference.org/ref/epsg/mgi-austria-gk-central/" rel = "nofollow" > EPSG:31255< / a > ).
This truncated CRS corresponds to a proj4 string< / p >
< div class = "snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content = "+proj=tmerc + lat_0 = 0 + lon_0 = 13d20 + k = 1
+x_0=0 +y_0=-5200000 +ellps=bessel
+towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232 +units=m +no_defs">< pre class = "notranslate" > < code > +proj=tmerc +lat_0=0 +lon_0=13d20 +k=1
+x_0=0 +y_0=-5200000 +ellps=bessel
+towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232 +units=m +no_defs
< / code > < / pre > < / div >
< p dir = "auto" > (...this should be all on one line).
This is derived from the proj4 string for
< a href = "https://spatialreference.org/ref/epsg/mgi-austria-gk-central/" rel = "nofollow" > EPSG:31255< / a >
by changing the < code > +y_0< / code > entry.< / p >
< p dir = "auto" > For more details and examples of survex < code > *cs< / code > commands see
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< a href = "https://github.com/patrickbwarren/qgis3-survex-import/blob/master/cave_surveying_and_gis.pdf" > cave_surveying_and_gis.pdf< / a > ."< br / > Local copy of < a href = "/expofiles/documents/surveying/cave_surveying_and_GIS.pdf" > cave_surveying_and_GIS.pdf< / a > (downloaded 2023-09-30).< / p >
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< h3 > Original description - Historical record< / h3 >
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< p > [See Wookey's article on very early GPS shennaninghans too: < a href = "/years/1996/gps.htm" > GPS For Expedition cave location< / a > which records our first tangles with G& K.]
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< p > The coordinate system used by the Austrian Kataster is called the
Gauß + Krü ger Landeskoordinatensystem, which is supposedly
identical to the widely used Universal Transverse Mercator system (Gauß
analysed the projection in 1822 and Krü ger published formulae to
translate to/from Lat/Long in 1912). In our area, this is UTM zone 31. At
least, this was our belief, but we don't seem to be getting perfect agreement
between UTM/31 figures from GPS and the G& K coordinates of fixed
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points... This is probably because the bulk of Austria is in UTM zone 33
which you will see if you use a GPS, which will give coordinates in zone 33T.
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Hmmmm. [See < a href = "https://hoehle.org/downloads/SD_10_Handbuch.pdf" > SD 10 Handbook, paras 8.7 and 8.8: Ö K 50-UTM< / a > for a possible explanation - Ed.]< / p >
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< p > Within this system, there are a number of triangulation points surveyed
purely for the purpose of locating caves: these are the
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Katastertriangulierungspunkte, or KT points. A point to watch when reading the
Austrian literature is that the numbers labelled X and Y are the opposite way
round from what seems normal to most people, ie. X is the northing and Y is the
easting. The X coordinate, when quoted in full, is actually the distance in
metres north of the equator, but usually the leading two digits are omitted, to
give the same number of digits in the two coordinates. When the two extra
digits are quoted, then the coordinates are not the same length, which can
cause confusion if you're used to British National Grid references (where the
east and west coordinates are run together as if a single number).< / p >
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< p > Within our area, a number of derivative points were surveyed (with a laser
rangefinder/theodolite) near to various caves. This work was done in two
sessions, in summer 1987 (with CUCC) and in 199x (with ArGe?). The points are
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marked with spits in the rock, and originally with some form of flagging tape.
However, those which aren't right next to well-known caves are now proving
quite hard to find in the field, at least partly owing to some very poor
sketching of their locations.< / p >
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< p > For these derived points, the main number is just a sequence number. The
ones which were derived via an intermediate derived point (rather than
directly from KT points) have a prefix indicating the point from which they
were derived. Hence, for example, point 7/9 on the 201 path near
Elchhö hle, was the ninth derived point, and was found by theodoliting
and rangefinding from point 7, on the Brä uning Nase. This numbering
makes it easier, if one point is found to be in error, to work out which ones
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were derived from it and will therefore also be wrong.< / p >
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< p > As far as we are aware, all of these points which we have visited are
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correct, with the exception of 7/11 on the col between the SMK ridge and
the Nase (not far the old Nase Top Camp), which seems to be out by an angular
error of 25 or 26° from the Nase point. In the table, point 14/16 is also
noted as possibly being dodgy, but we have no real indication of why.< / p >
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< p > This table shows the coordinates of the laser points in UTM using the WGS84
datum, which is the coordinate system we now use for the expo dataset (and
which the Austrian's kataster also now uses). If you want the original
coordinates, see the < i > *fix< / i > commands in the file fixedpts/laser.svx
in the Survex dataset.< / p >
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< table class = "trad" >
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< tr > < th > Code< / th > < th > Easting< / th > < th > Northing< / th > < th > Altitude< / th > < th >
Description< / th > < / tr >
< tr > < td > KT114-96< / td > < td > 411524.92< / td > < td > 5282241.69< / td > < td > 1950.78< / td > < td >
Hinterer Schwarzmooskogel Trig point< / td > < / tr >
< tr > < td > 0< / td > < td > 411230.25< / td > < td > 5281734.79< / td > < td > 1862.27< / td > < td >
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Hilfstandpunkt (hillock N of < a href = "/1623/161/top.htm" > 161< / a > )< / td > < / tr >
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< tr > < td > 0/1< / td > < td > 410927.39< / td > < td > 5281274.61< / td > < td > 1829.18< / td > < td >
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Between < a href = "/1623/156/156.html" > 156< / a > and < a href = "/1623/201.htm" > 201< / a > . Cloth labelled "0/1" replaced with alloy tag "LASER 0/1" (1999)< / td > < / tr >
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< tr > < td > 0/2< / td > < td > 410865.82< / td > < td > 5281370.64< / td > < td > 1796.89< / td > < td >
Near 0/1< / td > < / tr >
< tr > < td > 0/3< / td > < td > 410702.33< / td > < td > 5281366.04< / td > < td > 1756.99< / td > < td >
Near 0/2< / td > < / tr >
< tr > < td > 0/4< / td > < td > 410765.94< / td > < td > 5281478.20< / td > < td > 1734.28< / td > < td >
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< a href = "/1623/145/145.html" > Wolfhö hle< / a > < / td > < / tr >
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< tr > < td > 0/5< / td > < td > 410849.40< / td > < td > 5281721.63< / td > < td > 1737.52< / td > < td >
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up gully and left from < a href = "/1623/107.htm" > 107< / a >
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tatty cloth replaced with alloy tag "LASER 0/5" 1998< / td > < / tr >
< tr > < td > 0/6< / td > < td > 410720.07< / td > < td > 5281885.87< / td > < td > 1694.60< / td > < td >
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Near < a href = "/1623/76/76.htm" > 76< / a > - between the three entrances. Very faded blue cloth replaced with alloy tag "LASER 0/6" in 2006< / td > < / tr >
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< tr > < td > 0/7< / td > < td > 410251.61< / td > < td > 5281188.86< / td > < td > 1816.60< / td > < td >
Brä uning Nase< / td > < / tr >
< tr > < td > 7/8< / td > < td > 410857.13< / td > < td > 5280461.49< / td > < td > 1779.22< / td > < td >
Felskuppe im Bereich des Vd. Schwarzmooskogel (Weiß e Warze, The Nipple, Bunter's Bulge)< / td > < / tr >
< tr > < td > 7/9< / td > < td > 410201.88< / td > < td > 5279997.48< / td > < td > 1635.15< / td > < td >
Elchhö hle < a href = "../../noinfo/1623/31.htm" > 1623/31< / a > . Punkt am Weg (point in the path)< / td > < / tr >
< tr > < td > 7/10< / td > < td > 410445.91< / td > < td > 5280892.78< / td > < td > 1676.80< / td > < td >
Kratzer Valley below the col< / td > < / tr >
< tr > < td > 7/11< / td > < td > 410494.46< / td > < td > 5281341.02< / td > < td > 1729.50< / td > < td >
Schwarzmoossattel (the col) - < i > we believe this is in error< / i > < / td > < / tr >
< tr > < td > 8/12< / td > < td > 410744.26< / td > < td > 5280640.97< / td > < td > 1771.87< / td > < td >
< / td > < / tr >
< tr > < td > 8/13< / td > < td > 410997.27< / td > < td > 5280882.83< / td > < td > 1821.97< / td > < td >
< / td > < / tr >
< tr > < td > 8/14< / td > < td > 411278.13< / td > < td > 5280630.13< / td > < td > 1736.31< / td > < td >
Schwarzmooskogeleishö hle < a href = "../../noinfo/1623/40.htm" > 1623/40a< / a > < / td > < / tr >
< tr > < td > 14/15< / td > < td > 411285.73< / td > < td > 5280680.75< / td > < td > 1733.49< / td > < td >
< / td > < / tr >
< tr > < td > 14/16< / td > < td > 411374.72< / td > < td > 5280464.78< / td > < td > 1707.22< / td > < td >
(possibly dodgy ?)< / td > < / tr >
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< / table >
< p > In some Austrian literature, the easting quoted is in a system labelled
BMN. The Easting grid line +36000 (Gauß + Krü ger, M31) is the
same as BMN 486000, and translation appears to be a matter of simple
addition or subtraction, though it may prove to be more complex than this
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over a large enough area, as already indicated by GPS work...< / p >
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< div >
< figure >
< a href = "../i/meridianstreifen.jpg" > < img src = "../t/meridianstreifen.jpg" > < / a >
< br > < br > < figcaption > Austrian Meridians< a href = "https://hoehle.org/downloads/SD_10_Handbuch.pdf" > SD 10 Handbook< / a > 8.7 - click to enlarge< / figcaption >
< / figure >
< / div >
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< hr > < / body >
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