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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
[adb5b75]	25	allows you to read other processed survey data formats (those from
	26	Larry Fish's Compass and from Bob Thrun's CMAP), and allows reading
	27	a sub-set of the data in a file, restricted by survey prefix.</P>
[2d82f2a]	28
[ec812baa]	29	<P>This document only describes the most recent revision of the 3d format
	30	(version 8) which is produced by versions from 1.2.7. A <a
	31	href="3dformat-old.htm">separate document</a> describes older versions.
	32	</P>
[618b01f]	33
	34	<P>If you try to use this specification and find details which aren't
	35	spelled out clearly enough (or at all!) or any errors, please let us know.
	36	At least two people have successfully written code to read 3d files
	37	using this document, but that doesn't mean it can't be improved.
	38	</P>
[2d82f2a]	39
	40	<H2>File Header</H2>
	41
[618b01f]	42	<P>This consists of:</P>
[2d82f2a]	43
	44	<ul>
[afe350e]	45	<li> File ID: the string "Survex 3D Image File" followed by a linefeed
	46	(decimal 10, hex 0a). [Note: v0.01 files can have a carriage return
[618b01f]	47	before this and other linefeeds - this is a file format error in any
	48	other format version].
[ec812baa]	49	<li> File format version: "v8" followed by a linefeed.
	50	Any future versions will be "v9", "v10", "v11", etc.
[17ec06d]	51	<li> Assorted string metadata - the sublist below lists these, and they
	52	must appear in the order given, separated by zero bytes, with the end of
	53	the metadata marked by a linefeed. More items may be added, so ignore any
	54	additional ones which are present. Any trailing items with empty values
	55	can be omitted along with the separating zero byte before them.
	56	<ul>
	57	<li>Survey title: Human readable description of the data in the file.
	58	There's no length limit on this string.
[cf62988]	59	<li>Coordinate system: string describing the coordinate system in use
	60	which can be passed to PROJ. For a coordinate system with an EPSG code
[52a6209]	61	<code>EPSG:</code> followed by the code number can be used (we recommend
	62	using this if an EPSG code exists). Similarly, an ESRI code can be specified
	63	with <code>ESRI:</code> followed by the code number.
[5d59477]	64	<li>Survey hierarchy separator character. Survey station names form a
	65	hierarchy, and this character separates levels in the hierarchy. E.g.
	66	<code>161.entrance.6</code>. Defaults to <code>.</code> if this item is not
	67	specified, which is also the recommended character to use unless <code>.</code>
	68	is used in survey or station names (especially as older software will not see
	69	this metadata and will use <code>.</code> unconditionally).
[17ec06d]	70	</ul>
[ec812baa]	71	<li> Timestamp: A string consisting of an '@' followed by a count of
	72	seconds since the start of 1970 in UTC ("Unix time_t") as a string
	73	(for example: "@1371300355"), followed by a linefeed. This is intended to be
	74	the time the file was generated, rather than the time the survey data was
	75	collected.
[73fea40]	76	<li> File-wide flags: a single byte. If bit 7 is set, this is an extended
	77	elevation. All other bits are reserved - set them to 0 when writing, and
	78	ignore them when reading.
[2d82f2a]	79	</ul>
	80
	81	<H2>Items</H2>
	82
	83	<P>Following the header are a number of items. The last item must be a 0x00
	84	byte when the current label is empty, which marks the end of the data. The
[618b01f]	85	first byte of an item is a code identifying what the item is:</P>
[760a6550]	86
[618b01f]	87	<table border="1" cellpadding="1" cellspacing="0" width="100%">
	88	<tr>
	89	<th class="code">Code</th>
	90	<th class="code">Type</th>
	91	<th class="data">Data</th>
	92	<th class="desc" colspan="2">Meaning</th>
	93	<th class="version">Version</th>
	94	</tr>
	95	<tr>
	96	<td class="code">0x00</td>
[dec6b10]	97	<td class="type">STYLE_NORMAL / STOP</td>
[618b01f]	98	<td class="data"> </td>
[dec6b10]	99	<td colspan="2">
	100	Set style for following legs to tape, compass and clino.
	101	<p>
	102	If the style is already set to STYLE_NORMAL, this code signifies the
	103	end of the data in the 3d file.</td>
[ec812baa]	104	<td class="version">≥8</td>
[618b01f]	105	</tr>
	106	<tr>
[dec6b10]	107	<td class="code">0x01</td>
	108	<td class="type">STYLE_DIVING</td>
[618b01f]	109	<td class="data"> </td>
[dec6b10]	110	<td colspan="2">
	111	Set style for following legs to diving data</td>
	112	<td class="version">≥8</td>
	113	</tr>
	114	<tr>
	115	<td class="code">0x02</td>
	116	<td class="type">STYLE_CARTESIAN</td>
	117	<td class="data"> </td>
	118	<td colspan="2">
	119	Set style for following legs to cartesian data</td>
	120	<td class="version">≥8</td>
	121	</tr>
	122	<tr>
	123	<td class="code">0x03</td>
	124	<td class="type">STYLE_CYLPOLAR</td>
	125	<td class="data"> </td>
	126	<td colspan="2">
	127	Set style for following legs to cylindrical polar data</td>
[ec812baa]	128	<td class="version">≥8</td>
[618b01f]	129	</tr>
[dec6b10]	130	<tr>
	131	<td class="code">0x04</td>
	132	<td class="type">STYLE_NOSURVEY</td>
	133	<td class="data"> </td>
	134	<td colspan="2">
	135	Set style for following legs to unsurveyed</td>
	136	<td class="version">≥8</td>
	137	</tr>
	138	<tr class="reserved">
	139	<td class="code">0x05 - 0x0e</td>
	140	<td class="type"> </td>
	141	<td class="data"> </td>
	142	<td class="desc" colspan="3">Reserved</td>
	143	</tr>
[618b01f]	144	<tr>
	145	<td class="code">0x0f</td>
	146	<td class="type">MOVE</td>
	147	<td class="data"><x> <y> <z></td>
	148	<td class="desc" colspan="2">
	149	Set current position to the coordinates given. Coordinates
	150	are 4 byte little-endian signed integers representing
	151	values in centimetres (0.01 metres).</td>
[ec812baa]	152	<td class="version">≥8</td>
[618b01f]	153	</tr>
[22114ef]	154	<tr>
	155	<td class="code">0x10</td>
	156	<td class="type">DATE</td>
[618b01f]	157	<td class="data"> </td>
[22114ef]	158	<td colspan="2">
	159	No survey date information was specified.</td>
	160	<td class="version">≥8</td>
[618b01f]	161	</tr>
	162	<tr>
[22114ef]	163	<td class="code">0x11</td>
[618b01f]	164	<td class="type">DATE</td>
[1ee204e]	165	<td class="data"><date></td>
	166	<td colspan="2">
[0cf46f5]	167	Set survey date of legs: date is a 2 byte little-endian unsigned integer
[22114ef]	168	counting days from the start of 1900.</td>
[ec812baa]	169	<td class="version">≥8</td>
[1ee204e]	170	</tr>
	171	<tr>
[22114ef]	172	<td class="code">0x12</td>
[1ee204e]	173	<td class="type">DATE</td>
	174	<td class="data"><date1><datespan></td>
	175	<td colspan="2">
[0cf46f5]	176	Set survey date of legs to a range: date1 is a
	177	2 byte little-endian unsigned integer counting days since the start of
	178	1900, and datespan is an unsigned byte counting days from date1.</td>
[ec812baa]	179	<td class="version">≥8</td>
[618b01f]	180	</tr>
[1599605]	181	<tr>
[22114ef]	182	<td class="code">0x13</td>
[1ee204e]	183	<td class="type">DATE</td>
	184	<td class="data"><date1><date2></td>
	185	<td colspan="2">
[0cf46f5]	186	Set survey date of legs to a range: date1, date2 are
	187	2 byte little-endian unsigned integers counting days since the
	188	start of 1900.</td>
[ec812baa]	189	<td class="version">≥8</td>
[1ee204e]	190	</tr>
[22114ef]	191	<tr class="reserved">
	192	<td class="code">0x14 - 0x1e</td>
	193	<td class="type"> </td>
[1ee204e]	194	<td class="data"> </td>
[22114ef]	195	<td colspan="3">Reserved</td>
	196	</tr>
	197	<tr>
	198	<td class="code">0x1f</td>
	199	<td class="type">ERROR</td>
	200	<td class="data"><legs><length><E><H><V></td>
[1ee204e]	201	<td colspan="2">
[22114ef]	202	Error information for the current traverse. <legs> is the number of
	203	legs. <length> is the total length of the
	204	traverse in cm (0.01m). E, H and V are the error and the horizontal and
	205	vertical components in cm. (All values are 4 byte little-endian signed integers) </td>
[ec812baa]	206	<td class="version">≥8</td>
[1ee204e]	207	</tr>
[618b01f]	208	<tr class="reserved">
[22114ef]	209	<td class="code">0x20 - 0x2f</td>
[618b01f]	210	<td class="type"> </td>
	211	<td class="data"> </td>
	212	<td colspan="3">Reserved</td>
	213	</tr>
	214	<tr>
	215	<td class="code" rowspan="3">0x30 - 0x31</td>
	216	<td class="type" rowspan="3">XSECT</td>
[dec6b10]	217	<td class="data" rowspan="3"><label> <L> <R> <U> <D></td>
[618b01f]	218	<td colspan="2">
[589c6ec]	219	Modify the current label buffer according to <label> (see below for
	220	details). The updated contents of the label buffer give the full name of
	221	the survey station which these dimensions were measured at. Dimensions are
	222	2 byte little-endian signed integers representing values in centimetres
	223	(0.01 metres). Omitted dimensions are encoded as 0xffff. Station flags are
	224	(N & 0x01):
	225	</td>
[ec812baa]	226	<td class="version" rowspan="3">≥8</td>
[618b01f]	227	</tr>
	228	<tr>
	229	<th>Flag (N & 0x01)</th>
	230	<th>Meaning</th>
	231	</tr>
	232	<tr>
	233	<td>0x01</td>
	234	<td>Station is last one in this passage</td>
	235	</tr>
	236	<tr>
	237	<td class="code" rowspan="3">0x32 - 0x33</td>
	238	<td class="type" rowspan="3">XSECT</td>
[dec6b10]	239	<td class="data" rowspan="3"><label> <L> <R> <U> <D></td>
[618b01f]	240	<td colspan="2">
[589c6ec]	241	Modify the current label buffer according to <label> (see below for
	242	details). The updated contents of the label buffer give the full name of
	243	the survey station which these dimensions were measured at. Dimensions are
	244	4 byte little-endian signed integers representing values in centimetres
	245	(0.01 metres). Omitted dimensions are encoded as 0xffffffff.
	246	</td>
[ec812baa]	247	<td class="version" rowspan="3">≥8</td>
[618b01f]	248	</tr>
	249	<tr>
	250	<th>Flag (N & 0x01)</th>
	251	<th>Meaning</th>
	252	</tr>
	253	<tr>
	254	<td>0x01</td>
	255	<td>Station is last one in this passage</td>
	256	</tr>
	257	<tr class="reserved">
	258	<td class="code">0x34 - 0x3f</td>
	259	<td class="type"> </td>
	260	<td class="data"> </td>
	261	<td colspan="3">Reserved</td>
	262	</tr>
	263	<!-- Checked to here! -->
	264	<tr>
[dec6b10]	265	<td class="code" rowspan="8">0x40 - 0x7f</td>
	266	<td class="type" rowspan="8">LINE</td>
	267	<td class="data" rowspan="8"><label> <x> <y> <z></td>
	268	<td colspan="2">
[589c6ec]	269	Modify the current label buffer according to <label> (see below for
	270	details) - if <label> is omitted due to flag bit 0x20 being set then
	271	the current label buffer is used unmodified. The updated contents of the
	272	label buffer give the survey that the leg is in. Return leg from current
	273	position to coordinates given, and update current position to coordinates
	274	given.
	275	</td>
[dec6b10]	276	<td class="version" rowspan="5">≥8</td>
	277	</tr>
	278	<tr>
	279	<th>Flag (N & 0x3f)</th>
	280	<th>Meaning</th>
	281	</tr>
	282	<tr>
	283	<td>0x01</td>
	284	<td>Leg is above ground</td>
	285	</tr>
	286	<tr>
	287	<td>0x02</td>
	288	<td>Leg duplicates data in another leg (e.g. resurvey along a passage to
	289	tie into a known station)</td>
	290	</tr>
	291	<tr>
	292	<td>0x04</td>
	293	<td>Leg is a splay shot in a chamber (radial shots from a central point)</td>
	294	</tr>
	295	<tr class="reserved">
	296	<td>0x08</td>
	297	<td colspan="2">Reserved</td>
	298	</tr>
	299	<tr class="reserved">
	300	<td>0x10</td>
	301	<td colspan="2">Reserved</td>
	302	</tr>
[e133186]	303	<tr>
[dec6b10]	304	<td>0x20</td>
[e133186]	305	<td>No change to label (<label> omitted entirely)</td>
	306	<td class="version">≥8</td>
[dec6b10]	307	</tr>
	308	<tr>
[589c6ec]	309	<td class="code" rowspan="10">0x80 - 0xff</td>
	310	<td class="type" rowspan="10">LABEL</td>
	311	<td class="data" rowspan="10"><label> <x> <y> <z></td>
[618b01f]	312	<td colspan="2">
[589c6ec]	313	Modify the current label buffer according to <label> (see below for
	314	details). The updated contents of the label buffer give the survey
	315	station's full name.
	316	</td>
	317	<td class="version" rowspan="10">≥8</td>
[618b01f]	318	</tr>
	319	<tr>
	320	<td colspan="2">
[dec6b10]	321	The station flags are encoded in the bottom 7 bits of the item code:</td>
[618b01f]	322	</tr>
	323	<tr>
[dec6b10]	324	<th>Flag (N & 0x7f)</th>
[618b01f]	325	<th>Meaning</th>
	326	</tr>
	327	<tr>
	328	<td>0x01</td>
	329	<td>Station is on leg above ground</td>
	330	</tr>
	331	<tr>
	332	<td>0x02</td>
	333	<td>Station is on an underground leg (both may be true at an entrance)</td>
	334	</tr>
	335	<tr>
	336	<td>0x04</td>
	337	<td>Station is marked as an entrance (with *entrance)</td>
	338	</tr>
	339	<tr>
	340	<td>0x08</td>
	341	<td>Station is exported (i.e. may be used as a connection point to other
	342	surveys)</td>
	343	</tr>
	344	<tr>
	345	<td>0x10</td>
	346	<td>Station is a fixed point (control point)</td>
	347	</tr>
	348	<tr>
	349	<td>0x20</td>
[dec6b10]	350	<td>Station is anonymous</td>
[618b01f]	351	</tr>
[dec6b10]	352	<tr>
	353	<td>0x40</td>
	354	<td>Station is on the passage wall</td>
[618b01f]	355	</tr>
	356	</table>
[e77d6de]	357
[de844aa2]	358	<p>A <label> value in the table above encodes modifications to the
[589c6ec]	359	current label buffer, which consist of removing the last <i>D</i> bytes
	360	from the buffer, and then appending the next <i>A</i> bytes from the file
	361	to the buffer. <i>D</i> and <i>A</i> are encoded as follows:</p>
	362
	363	<ul>
	364	<li>Read a byte - if it is non-zero then: <i>D</i> = <code>byte >> 4</code>, <i>A</i> = <code>byte & 0x0f</code>
	365	<li>Otherwise (i.e. the first byte is zero):
	366	<ul>
	367	<li>Read a byte and:
	368	<ul>
	369	<li>If it is not 255 then <i>D</i> = <code>byte</code>
	370	<li>Otherwise, <i>D</i> = 4 byte unsigned integer read from the file
	371	</ul>
	372	<li>Read a byte and:
	373	<ul>
	374	<li>If it is not 255 then <i>A</i> = <code>byte</code>
	375	<li>Otherwise, <i>A</i> = 4 byte unsigned integer read from the file
	376	</ul>
	377	</ul>
	378	</ul>
	379
[618b01f]	380	<H2>Item order</H2>
[2d82f2a]	381	<ul>
[618b01f]	382	<li>A continuous section of centreline is defined by a <MOVE> item, followed
	383	by one or more <LINE> items.</li>
	384	<li><LABEL> items may appear anywhere in the file after the header,
	385	including within a <MOVE><LINE>... sequence.</li>
	386	<li>Duplicate <LABEL> items are permitted provided they also have identical
	387	coordinate values. (The same coordinate values may also be shared by any
	388	number of different <LABEL> items).</li>
	389	<li>Stations must be defined in a <LABEL> item <u>before</u> being
	390	referenced (e.g. in <XSECT> items)</li>
[2d82f2a]	391	</ul>
	392
[adb5b75]	393	<P>Authors: Olly Betts and Mike McCombe, last updated: 2025-01-13</P>
[2d82f2a]	394	</BODY></HTML>

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