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Last change on this file since ec812baa was ec812baa, checked in by Olly Betts <olly@…>, 12 years ago

doc/3dformat.htm,doc/TODO.htm,src/img.h: Start on v8 of the 3d format

the timestamp is stored as seconds since 1970.

Property mode set to 100644

File size: 11.2 KB

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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>
[618b01f]	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
	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.
[2d82f2a]	57	</ul>
	58
	59	<H2>Items</H2>
	60
	61	<P>Following the header are a number of items. The last item must be a 0x00
	62	byte when the current label is empty, which marks the end of the data. The
[618b01f]	63	first byte of an item is a code identifying what the item is:</P>
[760a6550]	64
[618b01f]	65	<table border="1" cellpadding="1" cellspacing="0" width="100%">
	66	<tr>
	67	<th class="code">Code</th>
	68	<th class="code">Type</th>
	69	<th class="data">Data</th>
	70	<th class="desc" colspan="2">Meaning</th>
	71	<th class="version">Version</th>
	72	</tr>
	73	<tr>
	74	<td class="code">0x00</td>
	75	<td class="type">STOP</td>
	76	<td class="data"> </td>
	77	<td class="desc" colspan="2">
	78	If the current label is empty, signifies the end of the data in the 3d
	79	file; if the current label isn't empty, make it empty.</td>
[ec812baa]	80	<td class="version">≥8</td>
[618b01f]	81	</tr>
	82	<tr>
	83	<td class="code">0x01 - 0x0e</td>
	84	<td class="type">TRIM</td>
	85	<td class="data"> </td>
	86	<td class="desc" colspan="2">
	87	Trim the last 16 characters of the current label, then trim back N (i.e.
	88	1-14) dots ("."), everything after that particular dot.
	89	It's incorrect if the label ends up empty, or you attempt to trim more
	90	label than there is. The rationale for removing 16 characters first is
	91	that removal of 1-16 characters can be encoded by 0x10-0x1f (see below)
	92	and we can make this encoding more powerful by not
	93	overlapping what can be encoded.</td>
[ec812baa]	94	<td class="version">≥8</td>
[618b01f]	95	</tr>
	96	<tr>
	97	<td class="code">0x0f</td>
	98	<td class="type">MOVE</td>
	99	<td class="data"><x> <y> <z></td>
	100	<td class="desc" colspan="2">
	101	Set current position to the coordinates given. Coordinates
	102	are 4 byte little-endian signed integers representing
	103	values in centimetres (0.01 metres).</td>
[ec812baa]	104	<td class="version">≥8</td>
[618b01f]	105	</tr>
	106	<tr>
	107	<td class="code">0x10 - 0x1f</td>
	108	<td class="type">TRIM</td>
	109	<td class="data"> </td>
	110	<td colspan="2">
	111	Remove N-15 (i.e. 1-16) characters from the current label. It's
	112	incorrect if the label ends up empty, or you attempt to trim more label
	113	than there is.</td>
[ec812baa]	114	<td class="version">≥8</td>
[618b01f]	115	</tr>
	116	<tr>
[1ee204e]	117	<td class="code">0x20</td>
[618b01f]	118	<td class="type">DATE</td>
[1ee204e]	119	<td class="data"><date></td>
	120	<td colspan="2">
[0cf46f5]	121	Set survey date of legs: date is a 2 byte little-endian unsigned integer
	122	counting days from the
	123	start of 1900.</td>
[ec812baa]	124	<td class="version">≥8</td>
[1ee204e]	125	</tr>
	126	<tr>
	127	<td class="code">0x21</td>
	128	<td class="type">DATE</td>
	129	<td class="data"><date1><datespan></td>
	130	<td colspan="2">
[0cf46f5]	131	Set survey date of legs to a range: date1 is a
	132	2 byte little-endian unsigned integer counting days since the start of
	133	1900, and datespan is an unsigned byte counting days from date1.</td>
[ec812baa]	134	<td class="version">≥8</td>
[618b01f]	135	</tr>
[1599605]	136	<tr>
	137	<td class="code">0x22</td>
	138	<td class="type">ERROR</td>
	139	<td class="data"><legs><length><E><H><V></td>
	140	<td colspan="2">
[0cf46f5]	141	Error information for the current traverse. <legs> is the number of
	142	legs. <length> is the total length of the
	143	traverse in cm (0.01m). E, H and V are the error and the horizontal and
	144	vertical components in cm. (All values are 4 byte little-endian signed integers) </td>
[ec812baa]	145	<td class="version">≥8</td>
[1599605]	146	</tr>
[1ee204e]	147	<tr>
	148	<td class="code">0x23</td>
	149	<td class="type">DATE</td>
	150	<td class="data"><date1><date2></td>
	151	<td colspan="2">
[0cf46f5]	152	Set survey date of legs to a range: date1, date2 are
	153	2 byte little-endian unsigned integers counting days since the
	154	start of 1900.</td>
[ec812baa]	155	<td class="version">≥8</td>
[1ee204e]	156	</tr>
	157	<tr>
	158	<td class="code">0x24</td>
	159	<td class="type">DATE</td>
	160	<td class="data"> </td>
	161	<td colspan="2">
[0cf46f5]	162	No survey date information was specified.</td>
[ec812baa]	163	<td class="version">≥8</td>
[1ee204e]	164	</tr>
[618b01f]	165	<tr class="reserved">
[1ee204e]	166	<td class="code">0x25 - 0x2f</td>
[618b01f]	167	<td class="type"> </td>
	168	<td class="data"> </td>
	169	<td colspan="3">Reserved</td>
	170	</tr>
	171	<tr>
	172	<td class="code" rowspan="3">0x30 - 0x31</td>
	173	<td class="type" rowspan="3">XSECT</td>
	174	<td class="data" rowspan="3"><len> <label> <L> <R> <U> <D></td>
	175	<td colspan="2">
	176	Dimensions are 2 byte little-endian signed integers representing values
	177	in centimetres (0.01 metres). Omitted dimensions are encoded as 0xffff.
	178	Station flags are (N & 0x01): </td>
[ec812baa]	179	<td class="version" rowspan="3">≥8</td>
[618b01f]	180	</tr>
	181	<tr>
	182	<th>Flag (N & 0x01)</th>
	183	<th>Meaning</th>
	184	</tr>
	185	<tr>
	186	<td>0x01</td>
	187	<td>Station is last one in this passage</td>
	188	</tr>
	189	<tr>
	190	<td class="code" rowspan="3">0x32 - 0x33</td>
	191	<td class="type" rowspan="3">XSECT</td>
	192	<td class="data" rowspan="3"><len> <label> <L> <R> <U> <D></td>
	193	<td colspan="2">
	194	Dimensions are 4 byte little-endian signed integers representing values
	195	in centimetres (0.01 metres). Omitted dimensions are encoded as
	196	0xffffffff.</td>
[ec812baa]	197	<td class="version" rowspan="3">≥8</td>
[618b01f]	198	</tr>
	199	<tr>
	200	<th>Flag (N & 0x01)</th>
	201	<th>Meaning</th>
	202	</tr>
	203	<tr>
	204	<td>0x01</td>
	205	<td>Station is last one in this passage</td>
	206	</tr>
	207	<tr class="reserved">
	208	<td class="code">0x34 - 0x3f</td>
	209	<td class="type"> </td>
	210	<td class="data"> </td>
	211	<td colspan="3">Reserved</td>
	212	</tr>
	213	<!-- Checked to here! -->
	214	<tr>
	215	<td class="code" rowspan="13">0x40 - 0x7f</td>
	216	<td class="type" rowspan="13">LABEL</td>
	217	<td class="data" rowspan="13"><len> <label> <x> <y> <z></td>
	218	<td colspan="2">
	219	Append label to the current label buffer. The updated contents of the
	220	label buffer give the survey stations full name. The length of label is
	221	given by length, which is encoded as follows:</td>
[ec812baa]	222	<td class="version" rowspan="12">≥8</td>
[618b01f]	223	</tr>
	224	<tr>
	225	<th>Length</th>
	226	<th>Encoding</th>
	227	</tr>
	228	<tr>
	229	<td>0 - 253</td>
	230	<td>byte 0x00 - 0xfd</td>
	231	</tr>
	232	<tr>
	233	<td>254-65789</td>
	234	<td>byte 0xfe 2 byte little-endian unsigned integer len-254 0x0000-0xffff</td>
	235	</tr>
	236	<tr>
	237	<td>65790 and greater</td>
	238	<td>byte 0xff 4 byte little-endian unsigned integer len
	239	0x000100fd-0xffffffff</td>
	240	</tr>
	241	<tr>
	242	<td colspan="2">
	243	The station flags are encoded in the bottom 6 bits of the item code:</td>
	244	</tr>
	245	<tr>
	246	<th>Flag (N & 0x3f)</th>
	247	<th>Meaning</th>
	248	</tr>
	249	<tr>
	250	<td>0x01</td>
	251	<td>Station is on leg above ground</td>
	252	</tr>
	253	<tr>
	254	<td>0x02</td>
	255	<td>Station is on an underground leg (both may be true at an entrance)</td>
	256	</tr>
	257	<tr>
	258	<td>0x04</td>
	259	<td>Station is marked as an entrance (with *entrance)</td>
	260	</tr>
	261	<tr>
	262	<td>0x08</td>
	263	<td>Station is exported (i.e. may be used as a connection point to other
	264	surveys)</td>
	265	</tr>
	266	<tr>
	267	<td>0x10</td>
	268	<td>Station is a fixed point (control point)</td>
	269	</tr>
	270	<tr class="reserved">
	271	<td>0x20</td>
	272	<td colspan="2">Reserved</td>
	273	</tr>
	274	<tr>
	275	<td class="code" rowspan="8">0x80 - 0xbf</td>
	276	<td class="type" rowspan="8">LINE</td>
	277	<td class="data" rowspan="8"><len> <label> <x> <y> <z></td>
	278	<td colspan="2">
	279	Append label to the current label buffer. The length of the label is
	280	encoded as for a station label above. Return leg from current position
	281	to coordinates given, and update current position to coordinates given.
	282	The updated contents of the label buffer give the survey that the leg is
	283	in.</td>
[ec812baa]	284	<td class="version" rowspan="5">≥8</td>
[618b01f]	285	</tr>
	286	<tr>
	287	<th>Flag (N & 0x3f)</th>
	288	<th>Meaning</th>
	289	</tr>
	290	<tr>
	291	<td>0x01</td>
	292	<td>Leg is above ground</td>
	293	</tr>
	294	<tr>
	295	<td>0x02</td>
	296	<td>Leg duplicates data in another leg (e.g. resurvey along a passage to
	297	tie into a known station)</td>
	298	</tr>
	299	<tr>
	300	<td>0x04</td>
	301	<td>Leg is a splay shot in a chamber (radial shots from a central point)</td>
	302	</tr>
	303	<tr class="reserved">
	304	<td>0x08</td>
	305	<td colspan="2">Reserved</td>
	306	</tr>
	307	<tr class="reserved">
	308	<td>0x10</td>
	309	<td colspan="2">Reserved</td>
	310	</tr>
	311	<tr class="reserved">
	312	<td>0x20</td>
	313	<td colspan="2">Reserved</td>
	314	</tr>
	315	<tr class="reserved">
	316	<td class="code">0xc0 - 0xff</td>
	317	<td class="type"> </td>
	318	<td class="data"> </td>
	319	<td colspan="3">Reserved</td>
	320	</tr>
	321	</table>
[e77d6de]	322
[618b01f]	323	<H2>Item order</H2>
[2d82f2a]	324	<ul>
[618b01f]	325	<li>A continuous section of centreline is defined by a <MOVE> item, followed
	326	by one or more <LINE> items.</li>
	327	<li><LABEL> items may appear anywhere in the file after the header,
	328	including within a <MOVE><LINE>... sequence.</li>
	329	<li>Duplicate <LABEL> items are permitted provided they also have identical
	330	coordinate values. (The same coordinate values may also be shared by any
	331	number of different <LABEL> items).</li>
	332	<li>Stations must be defined in a <LABEL> item <u>before</u> being
	333	referenced (e.g. in <XSECT> items)</li>
[2d82f2a]	334	</ul>
	335
[0cf46f5]	336	<P>Authors: Olly Betts and Mike McCombe, last updated: 2012-02-17</P>
[2d82f2a]	337	</BODY></HTML>

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