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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<meta http-equiv="Content-Type" content="text/html; charset=utf8" />
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<title>CUCC Expo Surveying Handbook: Laser points</title>
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<link rel="stylesheet" type="text/css" href="../../css/main2.css" />
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<body>
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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">
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<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>.
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It was written in 2001 and last seriously updated in 2006.
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These days the Austrians use WGS84 GPS like eveyone else.
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<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>
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<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>
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<a href="/katast.htm">The Austrian Kataster areas</a><br />
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<a href="https://hoehle.org/downloads/SD_10_Handbuch.pdf">SD 10 Handbook: Vergleich der ÖK 50 mit der neuen ÖK 50-UTM</a><br>
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<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 />
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"Many of the cave entrances are
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recorded using a truncated form of the MGI / Gauss-Krüger (GK) Central Austria
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CRS (the non-truncated form is
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<a href="https://spatialreference.org/ref/epsg/mgi-austria-gk-central/" rel="nofollow">EPSG:31255</a>).
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This truncated CRS corresponds to a proj4 string</p>
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<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
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+x_0=0 +y_0=-5200000 +ellps=bessel
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+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
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+x_0=0 +y_0=-5200000 +ellps=bessel
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+towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232 +units=m +no_defs
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</code></pre></div>
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<p dir="auto">(...this should be all on one line).
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This is derived from the proj4 string for
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<a href="https://spatialreference.org/ref/epsg/mgi-austria-gk-central/" rel="nofollow">EPSG:31255</a>
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by changing the <code>+y_0</code> entry.</p>
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<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
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Gauß + Krüger Landeskoordinatensystem, which is supposedly
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identical to the widely used Universal Transverse Mercator system (Gauß
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analysed the projection in 1822 and Krüger published formulae to
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translate to/from Lat/Long in 1912). In our area, this is UTM zone 31. At
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least, this was our belief, but we don't seem to be getting perfect agreement
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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
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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: ÖK 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
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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
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Austrian literature is that the numbers labelled X and Y are the opposite way
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round from what seems normal to most people, ie. X is the northing and Y is the
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easting. The X coordinate, when quoted in full, is actually the distance in
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metres north of the equator, but usually the leading two digits are omitted, to
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give the same number of digits in the two coordinates. When the two extra
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digits are quoted, then the coordinates are not the same length, which can
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cause confusion if you're used to British National Grid references (where the
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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
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rangefinder/theodolite) near to various caves. This work was done in two
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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.
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However, those which aren't right next to well-known caves are now proving
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quite hard to find in the field, at least partly owing to some very poor
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sketching of their locations.</p>
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<p>For these derived points, the main number is just a sequence number. The
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ones which were derived via an intermediate derived point (rather than
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directly from KT points) have a prefix indicating the point from which they
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were derived. Hence, for example, point 7/9 on the 201 path near
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Elchhöhle, was the ninth derived point, and was found by theodoliting
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and rangefinding from point 7, on the Bräuning Nase. This numbering
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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
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the Nase (not far the old Nase Top Camp), which seems to be out by an angular
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error of 25 or 26° from the Nase point. In the table, point 14/16 is also
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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
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datum, which is the coordinate system we now use for the expo dataset (and
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which the Austrian's kataster also now uses). If you want the original
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coordinates, see the <i>*fix</i> commands in the file fixedpts/laser.svx
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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>
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Description</th></tr>
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<tr><td>KT114-96</td><td> 411524.92</td><td> 5282241.69</td><td> 1950.78</td><td>
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Hinterer Schwarzmooskogel Trig point</td></tr>
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<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>
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Near 0/1</td></tr>
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<tr><td>0/3</td><td> 410702.33</td><td> 5281366.04</td><td> 1756.99</td><td>
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Near 0/2</td></tr>
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<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">Wolfhöhle</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>
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<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>
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Bräuning Nase</td></tr>
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<tr><td>7/8</td><td> 410857.13</td><td> 5280461.49</td><td> 1779.22</td><td>
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Felskuppe im Bereich des Vd. Schwarzmooskogel (Weiße Warze, The Nipple, Bunter's Bulge)</td></tr>
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<tr><td>7/9</td><td> 410201.88</td><td> 5279997.48</td><td> 1635.15</td><td>
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Elchhöhle <a href="../../noinfo/1623/31.htm">1623/31</a>. Punkt am Weg (point in the path)</td></tr>
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<tr><td>7/10</td><td> 410445.91</td><td> 5280892.78</td><td> 1676.80</td><td>
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Kratzer Valley below the col</td></tr>
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<tr><td>7/11</td><td> 410494.46</td><td> 5281341.02</td><td> 1729.50</td><td>
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Schwarzmoossattel (the col) - <i>we believe this is in error</i></td></tr>
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<tr><td>8/12</td><td> 410744.26</td><td> 5280640.97</td><td> 1771.87</td><td>
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</td></tr>
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<tr><td>8/13</td><td> 410997.27</td><td> 5280882.83</td><td> 1821.97</td><td>
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</td></tr>
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<tr><td>8/14</td><td> 411278.13</td><td> 5280630.13</td><td> 1736.31</td><td>
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Schwarzmooskogeleishöhle <a href="../../noinfo/1623/40.htm">1623/40a</a></td></tr>
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<tr><td>14/15</td><td> 411285.73</td><td> 5280680.75</td><td> 1733.49</td><td>
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</td></tr>
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<tr><td>14/16</td><td> 411374.72</td><td> 5280464.78</td><td> 1707.22</td><td>
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(possibly dodgy ?)</td></tr>
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</table>
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<p>In some Austrian literature, the easting quoted is in a system labelled
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BMN. The Easting grid line +36000 (Gauß + Krüger, M31) is the
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same as BMN 486000, and translation appears to be a matter of simple
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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 >
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<figure>
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<a href="../i/meridianstreifen.jpg"><img src="../t/meridianstreifen.jpg"></a>
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<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>
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</figure>
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</div>
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<hr></body>
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</html>
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