1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>TerrainTool - create surface topographic data for Survex and Therion</title>
<meta http-equiv="Content-Language" content="en-gb" />
<meta name="robots" content="robots.txt" />
<meta name="Copyright" content="Copyright (c) 2008 - 2020 Mike McCombe" />
<meta name="Rating" content="General" />
<meta name="revisit-after" content="25 Days" />
</head>
<body>
<div id="content">
<h1>TerrainTool</h1>
<p>
TerrainTool was written to create surface topographic data for the cave survey packages <a href="http://survex.com">Survex</a> and <a href="http://therion.speleo.sk">Therion</a>
using the results of the <a href="http://www2.jpl.nasa.gov/srtm/">Shuttle Radar Topography Mission</a> (SRTM) in which the shuttle <i>Endeavour</i> mapped the height of
the Earth's surface between the latitudes 60 degrees North and 56 degrees South - about 80% of the Earth's land mass. Published resolution was 1 arc-second for the US and its territories
and 3 arc-seconds elsewhere. The latter corresponds to about 90m at the equator. The resulting data is royalty-free and, for many countries, may be the only data publicly available.
TerrainTool is able to automatically download the "tiles" of data that it needs, directly from a USGS server.
</p>
<p>
Because the SRTM radar imaging worked by using an oblique scan of the earth's surface, it had problems with shadowing where, despite multiple passes, areas remained hidden, resulting in
voids in the data. This is particularly noticeable in mountainous areas. A subsequent project <a href="http://www.jpl.nasa.gov/news/news.cfm?release=2009-103">Advanced Spaceborne Thermal
Emission and Reflection Radiometer (ASTER)</a> used infra-red nadir-viewing camera (i.e. directly downward) which, in post-processing over multiple orbits created stereo images from which
height could be derived. This overcame the shadowing problem but the view could be obstructed by cloud and vegetation cover and suffered from "artefacts" - spurious features which are by-products
of the imaging process. On it's own, the ASTER Digital Elevation Model (DEM) is unsuitable for cave surveying.
</p>
<p>
Finally complete in February 2020, NASA released a new DEM by re-processing "global" 1 arc-second SRTM data and carefully filling in the voids with re-processed ASTER data.
The result, NASADEM, is thus the highest resolution void-free near-global DEM that we have available. The only disadvantages are
</p>
<ul>
<li>The tiles are typically 9 times the size of the 3 arc-second SRTM data, so they take longer to download and
process and occupy more disk space
</li>
<li>You need to be logged into an Earthdata account to download the data. Unfortunately, TerrainTool cannot to do this for you so auto-download is disabled. However,
signing up for an Earthdata account is quick and easy at <a href="https://urs.earthdata.nasa.gov/users/new/">https://urs.earthdata.nasa.gov/users/new/</a>
</li>
</ul>
<p>
With the completion of NASA DEM, this release of TerrainTool no longer directly supports the use of ASTER data since its use as a fill-in for voids in the SRTM
data has already been done. TerrainTool now only offers a choice of SRTM (because it is small and automatically downloadable) and NASA (because of its higher quality and resolution)
</p>
<p>Having logged in to your Earthdata account, you can find the NASADEM data by going to <a href="https://lpdaac.usgs.gov/products/nasadem_hgtv001/">
https://lpdaac.usgs.gov/products/nasadem_hgtv001/</a> ) selecting "Access Data" and "Download Data" next to "Data Pool" and clicking on the directory link will
take you to a huge page containing all the tiles, currently at <a href="https://e4ftl01.cr.usgs.gov/MEASURES/NASADEM_HGT.001/2000.02.11/">
https://e4ftl01.cr.usgs.gov/MEASURES/NASADEM_HGT.001/2000.02.11/</a> Please note that this URL might be subject to change without notice. The
page can take several minutes to download so don't panic if your browser freezes! Tile files are the ones ending ".zip" and preceded by the relevant lat/long
e.g. NASADEM_HGT_n52w003.zip You can download tiles with a browser. Do NOT try unpacking the zip files - TerrainTool reads them in zipped form.
</p>
<p>
TerrainTool does the following:-
</p>
<ul>
<li>
If required, automatically downloads SRTM data from the USGS server.
</li>
<li>
Converts between the spherical (Lat/Lon) coordinates used in the tiles and a variety of map coordinates used by cave surveyors so that the surface mesh and cave survey
can be combined in a single model based on the local map coordinate system. Coordinate systems currently supported include British (OSGB) grid, Irish grid,
UTM, French (Lambert conical projections), Austrian grids, Slovenian Grid and New Zealand's NZMG and NZTM2000. The internal design is intended to allow additional
coordinate systems to be added easily.
</li>
<li>
Re-samples the data using biaxial interpolation to create a rectangular mesh of user-specified spacing.
</li>
<li>
Displays a coloured topographic map of the mesh.
</li>
<li>
Adds a user-specified offset (3-D) to the coordinates to align with coordinates used for the underground survey.
</li>
<li>
Saves the mesh as surface data in Survex (.svx) or Therion (.th) format.
</li>
</ul>
<p>
The programme, written in Java, provides a conventional GUI-style interface and will run under Windows, Solaris, macOS and Linux operating systems. This version is built
to run with JDK 15 which can be downloaded free of charge from <a href="https://jdk.java.net/15/ ">https://jdk.java.net/15/ </a>. Source code is compatible
back to JDK 8 but the use of older Java versions is not recommended for security reasons.
</p>
<p>
"TerrainTool" was written by Mike McCombe who is very grateful to UBSS for giving it a home. Please feel free to contact Mike with feedback or requests for help at
mike<at>mikemccombe.co.uk or via the <a href="http://survex.com/maillist.html">Survex list</a>.
</p>
<h2>Installation</h2>
<p>
Sorry, there's no fancy package installer but as there's only one file it should be pretty straightforward.
</p>
<ol>
<li>
If you don't already have Open JDK 15 installed, <a href="https://jdk.java.net/15/ ">download</a> it from the Open JDK
website now. Windows users will need to set the system PATH variable to point to the JDK-15.0.1\bin directory and remove references to any earlier Java releases
</li>
<li>
<a href="TerrainTool.jar">Download the TerrainTool</a> "jar". Depending on your browser you may find that the file that arrives is called TerrainTool.zip. If this happens,
just rename it to be TerrainTool.jar. Do not try unpacking the ZIP file!
</li>
<li>
Double-clicking the jar file should start the programme. If you need to start it from a command line interface, try "java -jar TerrainTool.jar".
</li>
</ol>
<p>
Thanks to Wookey, TerrainTool has been available in Debian and Ubuntu since 2012 (7/'Wheezy' and 12.04/'Precise Pangolin' respectively). To install it select 'terraintool' in your favourite package manager (Upgrade Center, Synaptic, Aptitude) and install it.
On the command line do
</p>
<p>
sudo apt-get install terraintool
</p>
<p>
If your system has a firewall, you <i>may</i> need to tell it to allow java to have outgoing https access. Otherwise, it won't be able to download the SRTM data files from the
USGS site. This version of TerrainTool doesn't support Internet access via a proxy.
</p>
<h2>Driving Instructions</h2>
<p>
TerrainTool is a conventional GUI-based application with a menu bar and dialog boxes to gather user-information. To get started, do the following:
</p>
<ol>
<li>
Select the required <a href="#Coordinates">coordinate system</a> using the Options menu. If you're not using the NASA DEM
you'll also need to specify the <a href="#Region">region</a>
</li>
<li>
Go to <a href="#Create">Create</a> on the File menu to specify the size, location and resolution of the mesh.
</li>
<li>
<a href="#Save_as">Save</a> the results as in Survex (.svx) or Therion (.th) format
</li>
<li>
Use Survex to process the file and Aven to view the results in 3D. Remember to enable viewing of surface legs in Aven!
</li>
<li>
Use the Offset command in the Options menu to fully align the terrain data with the coordinates used in your survey.
</li>
<li>
When generating surface data in Therion format, Therion needs to be told the coordinate system used for the surface data in a form that it recognises (e.g. EPSG:27700).
See the description of the surface command in the Therion Book for more details. </li>
<li>
Incorporate the terrain data into your survey project.
</li>
</ol>
<h3>File Menu</h3>
<p>
<strong><a name="Create" id="Create">Create</a></strong>... is used to calculate the terrain mesh. A dialog box is used to gather the following:-
</p>
<table class="ubsstable">
<tr>
<th>
Item
</th>
<th>
Meaning
</th>
</tr>
<tr>
<td>
Grid Reference
</td>
<td>
The grid reference for the mesh, expressed in the current coordinate type. This point can be at the centre of the mesh, any of the corners or the mid-point of any of the sides
(see below). An example in the correct format is shown below the text field.
</td>
</tr>
<tr class="altRow">
<td>
E-W Range
</td>
<td>
The distance (in metres) between the East and West edges of the mesh.
</td>
</tr>
<tr>
<td>
N-S Range
</td>
<td>
The distance (in metres) between the North and South edges of the mesh.
</td>
</tr>
<tr class="altRow">
<td>
Spacing
</td>
<td>
The distance (in metres) between adjacent cells in the mesh.
</td>
</tr>
<tr>
<td>
Grid ref is at
</td>
<td>
Specifies where current point (see "Grid Reference" above) lies in relation to the boundaries of the mesh.
</td>
</tr>
</table>
<p>
Pressing <strong>OK</strong> starts the calculation of the mesh points. If using the SRTM DEM and "Auto-download" is enabled, data files will be downloaded as needed
from the USGS server. These are
stored in the data directory for later re-use if necessary, avoiding the need to download the same file again. On Windows this will be in a directory called ".terraintool"
in the user's top-level directory on the system drive e.g. C:\Users\mike\.terraintool and on Unix/linux at ~/.local/share/terraintool/
</p>
<p>
At the end of the calculation, results are displayed as a simple coloured relief map. The mouse position is displayed (in current coordinates) in the message bar on the
bottom edge of the frame.
</p>
<p>
<strong>Lat/Long</strong>... provides a means of defining the current point in terms of latitude and longitude, rather than as a grid reference. If the point can be represented
as a valid grid reference in the current coordinate system, it is used to initialise the "Grid Reference" field of the "Create..." dialog box. Likewise, the current grid reference is used
to initialise the Lat and Long fields with the latitude and longitude of the current point.
</p>
<p>
Latitude and longitude values can be expressed as either
</p>
<ul>
<li>
real values in degrees (e.g. 46.25), where negative values are West / South, or
</li>
<li>
values in degrees, minutes and seconds (e.g. 46 N 15' 22.6")
</li>
</ul>
<p>
Latitude and Longitude are usually based on the WGS-84/GRS-80 datum and ellipsoid. The user may select alternatives, which will cause the lat and long values to be
re-calculated.
</p>
<p>
<strong><a name="Save_as" id="Save_as">Save as</a>...</strong>
</p>
<p>
Once a mesh has been calculated, the "Save as..." command can be used to save the terrain data. Normally, this will be in Survex (.svx) or Therion (.th) format.
</p>
<p>
Otherwise, height values are defined for each point in the mesh. Easting and Northing values are those of the current coordinate system.
</p>
<h3>
Options Menu
</h3>
<p>
<strong><a name="Coordinates" id="Coordinates">Coordinates</a>...</strong>
</p>
<p>
This is used to select the type of coordinates to use. The following are currently supported:
</p>
<table class="ubbsstable">
<tr>
<th>
Coordinate System
</th>
<th> </th>
</tr>
<tr>
<td>
Austrian
</td>
<td>
The Austrian (BMN) coordinate system, in three zones
</td>
</tr>
<tr class="altRow">
<td>
Irish Grid
</td>
<td>
The Irish grid system, used in both Northern Ireland and the Republic of Ireland.
</td>
</tr>
<tr>
<td>
Lambert 93
</td>
<td>
The Lambert 93 coordinate system. A conformal conical projection occasionally used in France.
</td>
</tr>
<tr class="altRow">
<td>
Lambert (5 zones)
</td>
<td>
The coordinate system most commonly used in France. Three zones (I, II and III) cover North, Central and Southern France. Zone IV is used in Corsica. A fifth zone (II-extended)
covers the whole of France, at the expense of greater distortion.
</td>
</tr>
<tr>
<td>
NZMG
</td>
<td>
New Zealand Map Grid - New Zealand’s coordinate system superseded in 2010. Maps based on this are no longer available, but still widely used. Based on a conformal orthomorphic projection.
</td>
</tr>
<tr class="altRow">
<td>
NZTM2000
</td>
<td>
New Zealand Transverse Mercator, successor to NZMG.
</td>
</tr>
<tr>
<td>
OSGB
</td>
<td>
Ordnance Survey of Great Britain - the normal British grid system.
</td>
</tr>
<tr class="altRow">
<td>
Slovenian Grid
</td>
<td>
A Transverse-Mercator grid used in Slovenia
</td>
</tr>
<tr>
<td>
UTM
</td>
<td>
Universal Transverse Mercator, devised by the US Department of Defense to cover the globe (except polar regions) in 60 zones. Also used by many national mapping agencies, often
with a national or regional datum instead of WGS84.
</td>
</tr>
</table>
<p>
One of the design objectives of this software is to be able to add further coordinate systems with minimal difficulty.
</p>
<p>
Selecting a coordinate system from the drop-down list results in automatic selection of sensible defaults for the datum and ellipsoid. The user is free to override this
selection using the other two drop-down lists. Whilst, for example, OSGB invariably uses its own datum and the "Airy Sphere", other systems are frequently used with a
variety of datums. UTM, for example, is used in Spain with the European (1950) Datum and Australia with their own (MGI) datum.
</p>
<p>
<strong>Auto download</strong> enables/disables the automatic downloading of SRTM data from the USGS site. This option is disabled when the NASA DEM is selected.
</p>
<p>
<strong><a name="Region" id="Region">Region</a></strong>
</p>
<p>
The SRTM data site is organised into six regions - Africa, Australia, Eurasia, North_America, South_America and Islands (New Zealand and islands of the Pacific). As I
don't have a simple method of determining the region automatically from lat/lon, you will need to manually select the right region. This option is only relevant
to the SRTM DEM. It is disabled when the NASA DEM is selected.
</p>
<p>
<strong><a name="Offset" id="Offset">Offset</a></strong>
</p>
<p>
This provides a simple way of adding a fixed 3-D offset to mesh point in the mesh as it is saved. You might want to do this because
</p>
<ul>
<li>
Your cave survey coordinates might not use the full easting and northing values
</li>
<li>
The height values differ from "known" surface heights in your survey. SRTM heights are referenced to EGM96 (Earth Geopotential Model 1996) and may be significantly
offset from a national height datum.
</li>
</ul>
<p>
<strong>NASA</strong>
</p>
<p>
Creates terrain using NASADEM data. Tiles for this DEM need to be manually installed. If a required tile is missing the error message will include the name of the
file that you need to find on the USGS server.
</p>
<p>
<strong>SRTM</strong>
</p>
<p>
Creates terrain using SRTM data. Any "voids" which cannot be filled by interpolation will result in gaps in the output data. If auto-download is selected and there
is an Internet connection, missing tiles will be automatically downloaded from the USGS server.
</p>
</div>
</body>
</html>
|
