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[618b01f]	1	<!DOCTYPE HTML PUBLIC "-//W4C//DTD HTML 4.0 Transitional//EN">
[2d82f2a]	2	<HTML><HEAD>
	3	<TITLE>Survex 3d Format Specification</TITLE>
	4	<STYLE type="text/css"><!--
[618b01f]	5	BODY, TD, TH, CENTER, UL, OL {font-family: sans-serif;}
	6	TD, TH {font-size: 11pt; vertical-align: top;}
	7	TH {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;}
	13	TH.data, TH.desc {text-align: center;}
	14	.reserved {background-color: #ddd;}
[2d82f2a]	15	-->
	16	</STYLE>
	17	</HEAD><BODY BGCOLOR=white TEXT=black>
	18	<H1>Survex 3d Format Specification</H1>
	19
[618b01f]	20	<P>If you're writing in C or C++ it's <b>strongly</b> recommended
	21	that you use the img routine provided with Survex to read and write
	22	3d files. Doing so means that you can take advantage of any revisions
	23	to the 3d format by simply rebuilding your software with the updated
	24	img routines, rather than having to update your own code. It also
	25	allows you to read a sub-set of the data in the file, restricted by
	26	Survey prefix.</P>
[2d82f2a]	27
[ec812baa]	28	<P>This document only describes the most recent revision of the 3d format
	29	(version 8) which is produced by versions from 1.2.7. A <a
	30	href="3dformat-old.htm">separate document</a> describes older versions.
	31	</P>
[618b01f]	32
	33	<P>If you try to use this specification and find details which aren't
	34	spelled out clearly enough (or at all!) or any errors, please let us know.
	35	At least two people have successfully written code to read 3d files
	36	using this document, but that doesn't mean it can't be improved.
	37	</P>
[2d82f2a]	38
	39	<H2>File Header</H2>
	40
[618b01f]	41	<P>This consists of:</P>
[2d82f2a]	42
	43	<ul>
[afe350e]	44	<li> File ID: the string "Survex 3D Image File" followed by a linefeed
	45	(decimal 10, hex 0a). [Note: v0.01 files can have a carriage return
[618b01f]	46	before this and other linefeeds - this is a file format error in any
	47	other format version].
[ec812baa]	48	<li> File format version: "v8" followed by a linefeed.
	49	Any future versions will be "v9", "v10", "v11", etc.
	50	<li> Survey title: A string followed by a linefeed. There's no length limit on
	51	this string.
	52	<li> Timestamp: A string consisting of an '@' followed by a count of
	53	seconds since the start of 1970 in UTC ("Unix time_t") as a string
	54	(for example: "@1371300355"), followed by a linefeed. This is intended to be
	55	the time the file was generated, rather than the time the survey data was
	56	collected.
[73fea40]	57	<li> File-wide flags: a single byte. If bit 7 is set, this is an extended
	58	elevation. All other bits are reserved - set them to 0 when writing, and
	59	ignore them when reading.
[2d82f2a]	60	</ul>
	61
	62	<H2>Items</H2>
	63
	64	<P>Following the header are a number of items. The last item must be a 0x00
	65	byte when the current label is empty, which marks the end of the data. The
[618b01f]	66	first byte of an item is a code identifying what the item is:</P>
[760a6550]	67
[618b01f]	68	<table border="1" cellpadding="1" cellspacing="0" width="100%">
	69	<tr>
	70	<th class="code">Code</th>
	71	<th class="code">Type</th>
	72	<th class="data">Data</th>
	73	<th class="desc" colspan="2">Meaning</th>
	74	<th class="version">Version</th>
	75	</tr>
	76	<tr>
	77	<td class="code">0x00</td>
	78	<td class="type">STOP</td>
	79	<td class="data"> </td>
	80	<td class="desc" colspan="2">
	81	If the current label is empty, signifies the end of the data in the 3d
	82	file; if the current label isn't empty, make it empty.</td>
[ec812baa]	83	<td class="version">≥8</td>
[618b01f]	84	</tr>
	85	<tr>
	86	<td class="code">0x01 - 0x0e</td>
	87	<td class="type">TRIM</td>
	88	<td class="data"> </td>
	89	<td class="desc" colspan="2">
	90	Trim the last 16 characters of the current label, then trim back N (i.e.
	91	1-14) dots ("."), everything after that particular dot.
	92	It's incorrect if the label ends up empty, or you attempt to trim more
	93	label than there is. The rationale for removing 16 characters first is
	94	that removal of 1-16 characters can be encoded by 0x10-0x1f (see below)
	95	and we can make this encoding more powerful by not
	96	overlapping what can be encoded.</td>
[ec812baa]	97	<td class="version">≥8</td>
[618b01f]	98	</tr>
	99	<tr>
	100	<td class="code">0x0f</td>
	101	<td class="type">MOVE</td>
	102	<td class="data"><x> <y> <z></td>
	103	<td class="desc" colspan="2">
	104	Set current position to the coordinates given. Coordinates
	105	are 4 byte little-endian signed integers representing
	106	values in centimetres (0.01 metres).</td>
[ec812baa]	107	<td class="version">≥8</td>
[618b01f]	108	</tr>
	109	<tr>
	110	<td class="code">0x10 - 0x1f</td>
	111	<td class="type">TRIM</td>
	112	<td class="data"> </td>
	113	<td colspan="2">
	114	Remove N-15 (i.e. 1-16) characters from the current label. It's
	115	incorrect if the label ends up empty, or you attempt to trim more label
	116	than there is.</td>
[ec812baa]	117	<td class="version">≥8</td>
[618b01f]	118	</tr>
	119	<tr>
[1ee204e]	120	<td class="code">0x20</td>
[618b01f]	121	<td class="type">DATE</td>
[1ee204e]	122	<td class="data"><date></td>
	123	<td colspan="2">
[0cf46f5]	124	Set survey date of legs: date is a 2 byte little-endian unsigned integer
	125	counting days from the
	126	start of 1900.</td>
[ec812baa]	127	<td class="version">≥8</td>
[1ee204e]	128	</tr>
	129	<tr>
	130	<td class="code">0x21</td>
	131	<td class="type">DATE</td>
	132	<td class="data"><date1><datespan></td>
	133	<td colspan="2">
[0cf46f5]	134	Set survey date of legs to a range: date1 is a
	135	2 byte little-endian unsigned integer counting days since the start of
	136	1900, and datespan is an unsigned byte counting days from date1.</td>
[ec812baa]	137	<td class="version">≥8</td>
[618b01f]	138	</tr>
[1599605]	139	<tr>
	140	<td class="code">0x22</td>
	141	<td class="type">ERROR</td>
	142	<td class="data"><legs><length><E><H><V></td>
	143	<td colspan="2">
[0cf46f5]	144	Error information for the current traverse. <legs> is the number of
	145	legs. <length> is the total length of the
	146	traverse in cm (0.01m). E, H and V are the error and the horizontal and
	147	vertical components in cm. (All values are 4 byte little-endian signed integers) </td>
[ec812baa]	148	<td class="version">≥8</td>
[1599605]	149	</tr>
[1ee204e]	150	<tr>
	151	<td class="code">0x23</td>
	152	<td class="type">DATE</td>
	153	<td class="data"><date1><date2></td>
	154	<td colspan="2">
[0cf46f5]	155	Set survey date of legs to a range: date1, date2 are
	156	2 byte little-endian unsigned integers counting days since the
	157	start of 1900.</td>
[ec812baa]	158	<td class="version">≥8</td>
[1ee204e]	159	</tr>
	160	<tr>
	161	<td class="code">0x24</td>
	162	<td class="type">DATE</td>
	163	<td class="data"> </td>
	164	<td colspan="2">
[0cf46f5]	165	No survey date information was specified.</td>
[ec812baa]	166	<td class="version">≥8</td>
[1ee204e]	167	</tr>
[618b01f]	168	<tr class="reserved">
[1ee204e]	169	<td class="code">0x25 - 0x2f</td>
[618b01f]	170	<td class="type"> </td>
	171	<td class="data"> </td>
	172	<td colspan="3">Reserved</td>
	173	</tr>
	174	<tr>
	175	<td class="code" rowspan="3">0x30 - 0x31</td>
	176	<td class="type" rowspan="3">XSECT</td>
	177	<td class="data" rowspan="3"><len> <label> <L> <R> <U> <D></td>
	178	<td colspan="2">
	179	Dimensions are 2 byte little-endian signed integers representing values
	180	in centimetres (0.01 metres). Omitted dimensions are encoded as 0xffff.
	181	Station flags are (N & 0x01): </td>
[ec812baa]	182	<td class="version" rowspan="3">≥8</td>
[618b01f]	183	</tr>
	184	<tr>
	185	<th>Flag (N & 0x01)</th>
	186	<th>Meaning</th>
	187	</tr>
	188	<tr>
	189	<td>0x01</td>
	190	<td>Station is last one in this passage</td>
	191	</tr>
	192	<tr>
	193	<td class="code" rowspan="3">0x32 - 0x33</td>
	194	<td class="type" rowspan="3">XSECT</td>
	195	<td class="data" rowspan="3"><len> <label> <L> <R> <U> <D></td>
	196	<td colspan="2">
	197	Dimensions are 4 byte little-endian signed integers representing values
	198	in centimetres (0.01 metres). Omitted dimensions are encoded as
	199	0xffffffff.</td>
[ec812baa]	200	<td class="version" rowspan="3">≥8</td>
[618b01f]	201	</tr>
	202	<tr>
	203	<th>Flag (N & 0x01)</th>
	204	<th>Meaning</th>
	205	</tr>
	206	<tr>
	207	<td>0x01</td>
	208	<td>Station is last one in this passage</td>
	209	</tr>
	210	<tr class="reserved">
	211	<td class="code">0x34 - 0x3f</td>
	212	<td class="type"> </td>
	213	<td class="data"> </td>
	214	<td colspan="3">Reserved</td>
	215	</tr>
	216	<!-- Checked to here! -->
	217	<tr>
	218	<td class="code" rowspan="13">0x40 - 0x7f</td>
	219	<td class="type" rowspan="13">LABEL</td>
	220	<td class="data" rowspan="13"><len> <label> <x> <y> <z></td>
	221	<td colspan="2">
	222	Append label to the current label buffer. The updated contents of the
	223	label buffer give the survey stations full name. The length of label is
	224	given by length, which is encoded as follows:</td>
[ec812baa]	225	<td class="version" rowspan="12">≥8</td>
[618b01f]	226	</tr>
	227	<tr>
	228	<th>Length</th>
	229	<th>Encoding</th>
	230	</tr>
	231	<tr>
	232	<td>0 - 253</td>
	233	<td>byte 0x00 - 0xfd</td>
	234	</tr>
	235	<tr>
	236	<td>254-65789</td>
	237	<td>byte 0xfe 2 byte little-endian unsigned integer len-254 0x0000-0xffff</td>
	238	</tr>
	239	<tr>
	240	<td>65790 and greater</td>
	241	<td>byte 0xff 4 byte little-endian unsigned integer len
	242	0x000100fd-0xffffffff</td>
	243	</tr>
	244	<tr>
	245	<td colspan="2">
	246	The station flags are encoded in the bottom 6 bits of the item code:</td>
	247	</tr>
	248	<tr>
	249	<th>Flag (N & 0x3f)</th>
	250	<th>Meaning</th>
	251	</tr>
	252	<tr>
	253	<td>0x01</td>
	254	<td>Station is on leg above ground</td>
	255	</tr>
	256	<tr>
	257	<td>0x02</td>
	258	<td>Station is on an underground leg (both may be true at an entrance)</td>
	259	</tr>
	260	<tr>
	261	<td>0x04</td>
	262	<td>Station is marked as an entrance (with *entrance)</td>
	263	</tr>
	264	<tr>
	265	<td>0x08</td>
	266	<td>Station is exported (i.e. may be used as a connection point to other
	267	surveys)</td>
	268	</tr>
	269	<tr>
	270	<td>0x10</td>
	271	<td>Station is a fixed point (control point)</td>
	272	</tr>
	273	<tr class="reserved">
	274	<td>0x20</td>
	275	<td colspan="2">Reserved</td>
	276	</tr>
	277	<tr>
	278	<td class="code" rowspan="8">0x80 - 0xbf</td>
	279	<td class="type" rowspan="8">LINE</td>
	280	<td class="data" rowspan="8"><len> <label> <x> <y> <z></td>
	281	<td colspan="2">
	282	Append label to the current label buffer. The length of the label is
	283	encoded as for a station label above. Return leg from current position
	284	to coordinates given, and update current position to coordinates given.
	285	The updated contents of the label buffer give the survey that the leg is
	286	in.</td>
[ec812baa]	287	<td class="version" rowspan="5">≥8</td>
[618b01f]	288	</tr>
	289	<tr>
	290	<th>Flag (N & 0x3f)</th>
	291	<th>Meaning</th>
	292	</tr>
	293	<tr>
	294	<td>0x01</td>
	295	<td>Leg is above ground</td>
	296	</tr>
	297	<tr>
	298	<td>0x02</td>
	299	<td>Leg duplicates data in another leg (e.g. resurvey along a passage to
	300	tie into a known station)</td>
	301	</tr>
	302	<tr>
	303	<td>0x04</td>
	304	<td>Leg is a splay shot in a chamber (radial shots from a central point)</td>
	305	</tr>
	306	<tr class="reserved">
	307	<td>0x08</td>
	308	<td colspan="2">Reserved</td>
	309	</tr>
	310	<tr class="reserved">
	311	<td>0x10</td>
	312	<td colspan="2">Reserved</td>
	313	</tr>
	314	<tr class="reserved">
	315	<td>0x20</td>
	316	<td colspan="2">Reserved</td>
	317	</tr>
	318	<tr class="reserved">
	319	<td class="code">0xc0 - 0xff</td>
	320	<td class="type"> </td>
	321	<td class="data"> </td>
	322	<td colspan="3">Reserved</td>
	323	</tr>
	324	</table>
[e77d6de]	325
[618b01f]	326	<H2>Item order</H2>
[2d82f2a]	327	<ul>
[618b01f]	328	<li>A continuous section of centreline is defined by a <MOVE> item, followed
	329	by one or more <LINE> items.</li>
	330	<li><LABEL> items may appear anywhere in the file after the header,
	331	including within a <MOVE><LINE>... sequence.</li>
	332	<li>Duplicate <LABEL> items are permitted provided they also have identical
	333	coordinate values. (The same coordinate values may also be shared by any
	334	number of different <LABEL> items).</li>
	335	<li>Stations must be defined in a <LABEL> item <u>before</u> being
	336	referenced (e.g. in <XSECT> items)</li>
[2d82f2a]	337	</ul>
	338
[afe350e]	339	<P>Authors: Olly Betts and Mike McCombe, last updated: 2013-07-10</P>
[2d82f2a]	340	</BODY></HTML>

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