source: git/doc/3dformat.htm @ 4fdc9e6

RELEASE/1.1RELEASE/1.2debug-cidebug-ci-sanitisersfaster-cavernloglog-selectstereostereo-2025walls-datawalls-data-hanging-as-warningwarn-only-for-hanging-survey
Last change on this file since 4fdc9e6 was 618b01f, checked in by Olly Betts <olly@…>, 20 years ago

Updated 3d format spec to cover v5

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1<!DOCTYPE HTML PUBLIC "-//W4C//DTD HTML 4.0 Transitional//EN">
2<HTML><HEAD>
3<TITLE>Survex 3d Format Specification</TITLE>
4<STYLE type="text/css"><!--
5BODY, TD, TH, CENTER, UL, OL {font-family: sans-serif;}
6TD, TH {font-size: 11pt; vertical-align: top;}
7TH {white-space: nowrap; background-color: #ffc;}
8.code {text-align: center; white-space: nowrap;}
9.type {text-align: center; white-space: nowrap;}
10.data {text-align: left; white-space: nowrap;}
11.desc {text-align: left; white-space: wrap;}
12.version {text-align: center; white-space: wrap;}
13TH.data, TH.desc {text-align: center;}
14.reserved {background-color: #ddd;}
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16</STYLE>
17</HEAD><BODY BGCOLOR=white TEXT=black>
18<H1>Survex 3d Format Specification</H1>
19
20<P>If you're writing in C or C++ it's <b>strongly</b> recommended
21that you use the img routine provided with Survex to read and write
223d files.  Doing so means that you can take advantage of any revisions
23to the 3d format by simply rebuilding your software with the updated
24img routines, rather than having to update your own code.  It also
25allows you to read a sub-set of the data in the file, restricted by
26Survey prefix.</P>
27
28<P>This document only describes the more recent revisions of the 3d format
29(versions 3, 4, and 5).
30Version 3 was produced by Survex versions 0.97 and later,
31version 4 by Survex 1.1.0-1.1.3, and Version 5 by versions from 1.1.4.</P>
32
33<P>If you try to use this specification and find details which aren't
34spelled out clearly enough (or at all!) or any errors, please let us know.
35At least two people have successfully written code to read 3d files
36using this document, but that doesn't mean it can't be improved.
37</P>
38
39<H2>File Header</H2>
40
41<P>This consists of:</P>
42
43<ul>
44<li>File ID: the string "Survex 3D Image File" followed by a linefeed
45(decimal 10, hex x0a). [Note: v0.01 files can have a carriage return
46before this and other linefeeds - this is a file format error in any
47other format version].
48<li>File format version: "v3", "v4", or "v5" followed by a linefeed.
49Any future versions will be "v6", "v7", ..., "v10", "v11", etc.
50Older format versions aren't described here, but had version strings
51"v0.01", "Bv0.01", "bv0.01", and "v2").
52<li> Survey title: A string followed by a linefeed.  There's no length limit on this string.
53<li> Timestamp: A string followed by a linefeed.  This is intended to be the
54time the file was generated, rather than the time the survey data was
55collected.  The easiest way to generate this is with the strftime() format
56"%a,%Y.%m.%d %H:%M:%S %Z" if you have access to strftime().  An example
57timestamp is "Sun,2002.03.17 14:01:07 GMT".
58</ul>
59
60<H2>Items</H2>
61
62<P>Following the header are a number of items.  The last item must be a 0x00
63byte when the current label is empty, which marks the end of the data.  The
64first byte of an item is a code identifying what the item is:</P>
65
66<table border="1" cellpadding="1" cellspacing="0" width="100%">
67<tr>
68    <th class="code">Code</th>
69    <th class="code">Type</th>
70    <th class="data">Data</th>
71    <th class="desc" colspan="2">Meaning</th>
72    <th class="version">Version</th>
73</tr>
74<tr>
75    <td class="code">0x00</td>
76    <td class="type">STOP</td>
77    <td class="data">&nbsp;</td>
78    <td class="desc" colspan="2">
79    If the current label is empty, signifies the end of the data in the 3d
80    file; if the current label isn't empty, make it empty.</td>
81    <td class="version">&ge;3</td>
82</tr>
83<tr>
84    <td class="code">0x01 - 0x0e</td>
85    <td class="type">TRIM</td>
86    <td class="data">&nbsp;</td>
87    <td class="desc" colspan="2">
88    Trim the last 16 characters of the current label, then trim back N (i.e.
89    1-14) dots ("."), everything after that particular dot.
90    It's incorrect if the label ends up empty, or you attempt to trim more
91    label than there is. The rationale for removing 16 characters first is
92    that removal of 1-16 characters can be encoded by 0x10-0x1f (see below)
93    and we can make this encoding more powerful by not
94    overlapping what can be encoded.</td>
95    <td class="version">&ge;3</td>
96</tr>
97<tr>
98    <td class="code">0x0f</td>
99    <td class="type">MOVE</td>
100    <td class="data">&lt;x&gt; &lt;y&gt; &lt;z&gt;</td>
101    <td class="desc" colspan="2">
102    Set current position to the coordinates given. Coordinates
103    are 4 byte little-endian signed integers representing
104    values in centimetres (0.01 metres).</td>
105    <td class="version">&ge;3</td>
106</tr>
107<tr>
108    <td class="code">0x10 - 0x1f</td>
109    <td class="type">TRIM</td>
110    <td class="data">&nbsp;</td>
111    <td colspan="2">
112    Remove N-15 (i.e. 1-16) characters from the current label. It's
113    incorrect if the label ends up empty, or you attempt to trim more label
114    than there is.</td>
115    <td class="version">&ge;3</td>
116</tr>
117<tr>
118    <td class="code">0x20</td>
119    <td class="type">DATE</td>
120    <td class="data">&lt;date&gt;</td>
121    <td colspan="2">
122    Set survey date of legs (date is 4 byte little endian unsigned integer
123    counting seconds since 1970) </td>
124    <td class="version">&ge;4</td>
125</tr>
126<tr>
127    <td class="code">0x21</td>
128    <td class="type">DATE</td>
129    <td class="data">&lt;date1&gt;&lt;date2&gt;</td>
130    <td colspan="2">
131    Set survey date of legs to a range (date1, date2 are 4 byte little
132    endian unsigned integer counting seconds since 1970) </td>
133    <td class="version">&ge;4</td>
134</tr>
135<tr class="reserved">
136    <td class="code">0x22 - 0x2f</td>
137    <td class="type">&nbsp;</td>
138    <td class="data">&nbsp;</td>
139    <td colspan="3">Reserved</td>
140</tr>
141<tr>
142    <td class="code" rowspan="3">0x30 - 0x31</td>
143    <td class="type" rowspan="3">XSECT</td>
144    <td class="data" rowspan="3">&lt;len&gt; &lt;label&gt; &lt;L&gt; &lt;R&gt; &lt;U&gt; &lt;D&gt;</td>
145    <td colspan="2">
146    Dimensions are 2 byte little-endian signed integers representing values
147    in centimetres (0.01 metres). Omitted dimensions are encoded as 0xffff.
148    Station flags are (N &amp; 0x01): </td>
149    <td class="version" rowspan="3">&ge;5</td>
150</tr>
151<tr>
152    <th>Flag (N &amp; 0x01)</th>
153    <th>Meaning</th>
154</tr>
155<tr>
156    <td>0x01</td>
157    <td>Station is last one in this passage</td>
158</tr>
159<tr>
160    <td class="code" rowspan="3">0x32 - 0x33</td>
161    <td class="type" rowspan="3">XSECT</td>
162    <td class="data" rowspan="3">&lt;len&gt; &lt;label&gt; &lt;L&gt; &lt;R&gt; &lt;U&gt; &lt;D&gt;</td>
163    <td colspan="2">
164    Dimensions are 4 byte little-endian signed integers representing values
165    in centimetres (0.01 metres). Omitted dimensions are encoded as
166    0xffffffff.</td>
167    <td class="version" rowspan="3">&ge;5</td>
168</tr>
169<tr>
170    <th>Flag (N &amp; 0x01)</th>
171    <th>Meaning</th>
172</tr>
173<tr>
174    <td>0x01</td>
175    <td>Station is last one in this passage</td>
176</tr>
177<tr class="reserved">
178    <td class="code">0x34 - 0x3f</td>
179    <td class="type">&nbsp;</td>
180    <td class="data">&nbsp;</td>
181    <td colspan="3">Reserved</td>
182</tr>
183<!-- Checked to here! -->
184<tr>
185    <td class="code" rowspan="13">0x40 - 0x7f</td>
186    <td class="type" rowspan="13">LABEL</td>
187    <td class="data" rowspan="13">&lt;len&gt; &lt;label&gt; &lt;x&gt; &lt;y&gt; &lt;z&gt;</td>
188    <td colspan="2">
189    Append label to the current label buffer. The updated contents of the
190    label buffer give the survey stations full name. The length of label is
191    given by length, which is encoded as follows:</td>
192    <td class="version" rowspan="12">&ge;3</td>
193</tr>
194<tr>
195    <th>Length</th>
196    <th>Encoding</th>
197</tr>
198<tr>
199    <td>0 - 253</td>
200    <td>byte 0x00 - 0xfd</td>
201</tr>
202<tr>
203    <td>254-65789</td>
204    <td>byte 0xfe 2 byte little-endian unsigned integer len-254 0x0000-0xffff</td>
205</tr>
206<tr>
207    <td>65790 and greater</td>
208    <td>byte 0xff 4 byte little-endian unsigned integer len
209    0x000100fd-0xffffffff</td>
210</tr>
211<tr>
212    <td colspan="2">
213    The station flags are encoded in the bottom 6 bits of the item code:</td>
214</tr>
215<tr>
216    <th>Flag (N &amp; 0x3f)</th>
217    <th>Meaning</th>
218</tr>
219<tr>
220    <td>0x01</td>
221    <td>Station is on leg above ground</td>
222</tr>
223<tr>
224    <td>0x02</td>
225    <td>Station is on an underground leg (both may be true at an entrance)</td>
226</tr>
227<tr>
228    <td>0x04</td>
229    <td>Station is marked as an entrance (with *entrance)</td>
230</tr>
231<tr>
232    <td>0x08</td>
233    <td>Station is exported (i.e. may be used as a connection point to other
234    surveys)</td>
235</tr>
236<tr>
237    <td>0x10</td>
238    <td>Station is a fixed point (control point)</td>
239</tr>
240<tr class="reserved">
241    <td>0x20</td>
242    <td colspan="2">Reserved</td>
243</tr>
244<tr>
245    <td class="code" rowspan="8">0x80 - 0xbf</td>
246    <td class="type" rowspan="8">LINE</td>
247    <td class="data" rowspan="8">&lt;len&gt; &lt;label&gt; &lt;x&gt; &lt;y&gt; &lt;z&gt;</td>
248    <td colspan="2">
249    Append label to the current label buffer. The length of the label is
250    encoded as for a station label above. Return leg from current position
251    to coordinates given, and update current position to coordinates given.
252    The updated contents of the label buffer give the survey that the leg is
253    in.</td>
254    <td class="version" rowspan="5">&ge;3</td>
255</tr>
256<tr>
257    <th>Flag (N &amp; 0x3f)</th>
258    <th>Meaning</th>
259</tr>
260<tr>
261    <td>0x01</td>
262    <td>Leg is above ground</td>
263</tr>
264<tr>
265    <td>0x02</td>
266    <td>Leg duplicates data in another leg (e.g. resurvey along a passage to
267    tie into a known station)</td>
268</tr>
269<tr>
270    <td>0x04</td>
271    <td>Leg is a splay shot in a chamber (radial shots from a central point)</td>
272</tr>
273<tr class="reserved">
274    <td>0x08</td>
275    <td colspan="2">Reserved</td>
276</tr>
277<tr class="reserved">
278    <td>0x10</td>
279    <td colspan="2">Reserved</td>
280</tr>
281<tr class="reserved">
282    <td>0x20</td>
283    <td colspan="2">Reserved</td>
284</tr>
285<tr class="reserved">
286    <td class="code">0xc0 - 0xff</td>
287    <td class="type">&nbsp;</td>
288    <td class="data">&nbsp;</td>
289    <td colspan="3">Reserved</td>
290</tr>
291</table>
292
293<H2>Item order</H2>
294<ul>
295<li>A continuous section of centreline is defined by a &lt;MOVE&gt; item, followed
296by one or more &lt;LINE&gt; items.</li>
297<li>&lt;LABEL&gt; items may appear anywhere in the file after the header,
298including within a &lt;MOVE&gt;&lt;LINE&gt;... sequence.</li>
299<li>Duplicate &lt;LABEL&gt; items are permitted provided they also have identical
300coordinate values. (The same coordinate values may also be shared by any
301number of different &lt;LABEL&gt; items).</li>
302<li>Stations must be defined in a &lt;LABEL&gt; item <u>before</u> being
303referenced (e.g. in &lt;XSECT&gt; items)</li>
304</ul>
305
306<P>Authors: Olly Betts and Mike McCombe, last updated: 2005-10-17</P>
307</BODY></HTML>
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