From 45fcc2d62e4d8c808051e20b43e0144c6051e2ca Mon Sep 17 00:00:00 2001 From: Philip Sargent Date: Thu, 13 Feb 2025 15:42:13 +0000 Subject: [PATCH] geoid and ellispoid --- handbook/survey/lasers.htm | 5 ++++- piclinks/ssvypl.htm | 11 ++++------- 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/handbook/survey/lasers.htm b/handbook/survey/lasers.htm index a025ae235..618c2abec 100644 --- a/handbook/survey/lasers.htm +++ b/handbook/survey/lasers.htm @@ -97,8 +97,11 @@ noted as possibly being dodgy, but we have no real indication of why.

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 *fix commands in the file fixedpts/laser.svx + coordinates, see the *fix commands in the file fixedpts/laser.svx in the Survex dataset.

+

[Just noticed in 2025: the altitudes in loser/fixedpts/laser.svx are not + te same as those in the table below. Current altitudes are 46.81m lower as we now measure altitude from + the geoid not the ellispoid; or possibly vice-versa.]

Code Easting Northing Altitude diff --git a/piclinks/ssvypl.htm b/piclinks/ssvypl.htm index ada30b3e1..9c7e42885 100644 --- a/piclinks/ssvypl.htm +++ b/piclinks/ssvypl.htm @@ -1,8 +1,6 @@ - -Surface Survey - Stellerweg area - +Surface Survey - Stellerweg area @@ -12,9 +10,9 @@ Schwarzmooskogel in 1983, above the Stellerweghöhle system.

This was the first attempt to find surface entrances corresponding to the large phreatic level of the 'Dartford Tunnel' area in 115, and specifically to find the surface location of the very -string outward draft at the end of the Fuitility Series (Nutzlos) found by Chas and Phil Sargent. +strong outward draft at the end of the Fuitility Series (Nutzlos) found by Chas and Phil Sargent. Phil had another look for these hoped-for entrances in 2018 and 2019, and learned that GPS altitudes are too poor -to be useful. We need to do more surface suyveying like this! +to be useful. We need to do more surface surveying like this!

Photo © Chas. Butcher, 1983. lookfutile.svx

@@ -33,6 +31,5 @@ to be useful. We need to do more surface suyveying like this!
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