(In progress!)
Metacave is a JSON cave survey data format. That means it's:
Metacave is the native format (with extensions) for Breakout and may someday also become the native format for Cavewhere.
In addition, Andy (author of Breakout) has import/export for Walls .srv files nearly
finished, and will have import/export for Compass .dat files soon as well (a much easier
job than parsing .srv files!
Always use UTF-8.
"in": inches
"ft": feet
"yd": yards
"m" : meters
"km": kilometers
"mi": miles"deg" : degrees
"min" : minutes (1/60 degree)
"sec" : seconds (1/60 minute)
"grad": gradians (1/400 circle)
"mil" : mils (1/6400 circle)"%" : percent grade{
"caves": { Required - this is where you define all
your survey measurements
"Fisher Ridge": { Everything inside here is in Fisher Ridge cave
If you connect to another cave, don't worry -
we'll cover how to handle that below
"fixedStations": [ This is where you define fixed station
locations. You can fix all stations in the
cave if you want to import/export calculated
loop closures from another program
{ This is a fixed station group, whose only
purpose is to specify the default units
"distUnit": "m", Required - the default unit for all distances
in this fixed station group
"ellipsoid": "WGS84", Required - must be WGS84, but this field is
required for the sake of making the data
unambiguous to a reader who hasn't read this
spec
"datum": "WGS84", Required - must be WGS84, but this field is
required for the sake of making the data
unambiguous to a reader who hasn't read this
spec
"stations": {
"A1": { This is the fixed position for station A1
"lat"/"long" pair must be defined using the WGS84
projection, specifically EPSG:4326.
"lat": "34.2342", Required angle - latitude
positive: north of equator
negative: south of equator
units: decimal degrees
"long": "-56.2313", Optional angle - longitude
positive: east of prime meridian
negative: west of prime meridian
units: decimal degrees
"elev": "345", Required distance - elevation
positive: above sea level
negative: below sea level
Default unit: "distUnit"
Units can be overridden using [value, "unit"] convension
for example [345, "ft"]
},
"Q5": { This is the fixed position for station Q5
...
},
...
}
},
{ (Another fixed station group)
...
},
...
],
"trips": [
{ This is the start of a trip
"name": "Tricky Traverse", Optional - a name for this trip
"date": "1981-02-14T00:00Z", Optional - the date of this trip, in ISO8601
format
"surveyors": { Optional - members of the survey team
"Dan Crowl": {
roles: "sketch"
},
"Chip Hopper": {
roles: "frontsights"
},
"Keith Ortiz": {
roles: "backsights"
},
"Peter Quick": {
roles: [ You can specify multiple roles in an array or scalar
"lead tape",
"photos"
]
},
"Larry Bean": null Use null if you don't want to specify a role
}
"distUnit": "ft", Required - the default unit for all distances
in this trip
"angleUnit": "deg", Required - the default unit for all angles in
this trip
Supported units:
"deg" : degrees
"grad": gradians
"mil" : mils (1/6400 of a circle)
"azmBacksightsCorrected": false, Required - true if azimuth backsights are corrected,
false if not
"incBacksightsCorrected": false, Required - true if inclinations backsights are corrected,
false if not
"declination": "0.0", Optional - the angle (in degrees) between
magnetic north and and true north
"azmFsUnit": "deg", Optional - overrides default unit for
frontsight azimuths
"azmBsUnit": "grad", Optional - overrides default unit for
backsight azimuths
"incFsUnit": "%", Optional - overrides default unit for
frontsight inclinations
Additional supported unit:
"%": percent grade
"incBsUnit": "mil", Optional - overrides default unit for
backsight inclinations
"distCorrection": "1.5", Optional distance - correction added to the
distances. Doesn't apply to LRUD/NSEW
Default unit: "distUnit"
"azmFsCorrection": "1", Optional angle - correction added to the
frontsight azimuths
Default unit: "azmFsUnit", then "angleUnit"
"azmBsCorrection": "2", Optional angle - correction added to the
backsight azimuths
Default unit: "azmBsUnit", then "angleUnit"
"incFsCorrection": "0", Optional angle - correction added to the
frontsight inclinations
Default unit: "incFsUnit", then "angleUnit"
"incBsCorrection": "0", Optional angle - correction added to the
backsight inclinations
Default unit: "incFsUnit", then "angleUnit"
"survey": [
{ This is a station. The survey must begin and
end with stations and have a shot in between
each pair of stations
Enter null where a station should be to turn
the surrounding shots into splay shots
"station": "A1", Required - the station name
"cave": "Mammoth Cave", Optional - specifies this station is in
a different cave, for connections. Stations
in different caves can have the same name, but
will be considered distinct
"isEntrance": true, Optional - true if the station is an entrance,
false (or omitted) if not
"isAboveGround": true, Optional - true if the station is above
ground, false (or omitted) if not
"depth": "4.25", Optional distance - depth underwater for dive
surveys (must be positive)
If two adjacent stations have depths,
inclinations can be omitted from the shot
connecting them
Default unit: "distUnit"
"lrud": ["5", "4", "0", "2"], Optional distances - the LRUDs at this
station. They will also be associated with
the surrounding shots
Default unit: "distUnit"
"lrudAzm": "3", Optional angle - the azimuth that is forward
relative to the LRUDs
If omitted, the default is bisecting the
previous and next shot azimuths
(unless station is a dead end, then
perpendicular to shot)
Default unit: "angleUnit"
"nsew": ["3", "2", "4", "6"], Optional distances - the NSEWs at this
station. They will also be associated with
the surrounding shots
Default unit: "distUnit"
"splays": [ Optional - Array of splay shots from the station. Each
object in the array represents a splay shot from the
station If this property is null, empty, or doesn't
exist there's no splay shots from this station.
{
"dir": "fs", Optional enumeration - The direction of the splay's
measurement. There are two supported directions:
"fs" and "bs", which are abbreviations for frontsight
and backsight respectivly. A frontsight are measurements
where the data was collected from current station
to the splay station. A backsight are where the data was
collected from the splay station to the current station.
Default value: "fs"
"dist": "15.3", optional distance - the distance between the current
station and the splay station.
If omitted, means the data is missing. This splay
shot distance is ignored from the total surveyed
distance.
Default unit: "distUnit"
"azm": "204.5", Optional angle - the azimuth of the splay shot
If omitted, means the data is missing
Default frontsight unit: "fsAzmUnit", then "angleUnit"
Default backsight unit: "bsAzmUnit", then "angleUnit"
"inc": "-5", Optional angle - the inclination of the splay
If omitted, means the data is missing or using station
depths (dive data has no inclination).
Default frontsight unit: "fsIncUnit", then "angleUnit"
Default backsight unit: "bsIncUnit", then "angleUnit"
"splayDepth": "4.25", Optional distance - depth underwater for dive at the
splay station (must be positive)
If current station has "depth" property and this
property exist inclinations can be omitted from the
splay shot
Default unit: "distUnit"
},
{ ... } Another splay shot from the station
]
},
{ This is a shot from the previous station to
the following station
Enter null where a shot should be to indicate
there is not a shot between the surrounding
stations (just like leaving a row of
measurements blank in survey notes)
"excludeDist": true, Optional - true if you want to exclude this
shot's dist from the total length of the cave,
false (or omitted) otherwise
"dist": "auto", Only allowed if the from and to station are
fixed and no azimuths or inclinations are
given; tells the program to draw passage
connecting the stations anyway
"measurements": [ Optional - Array of measurements between two stations.
If this property is null, empty, or doesn't exist
there's no measurements between two stations.
{
"dir": "fs", Optional enumeration - The direction of the shot's
measurement. There are two supported directions:
"fs" and "bs", which are abbreviations for frontsight
and backsight respectivly. A frontsight are measurements
where the data was collected from current station
to the next station. A backsight are where the data was
collected from the next station to the current station.
Default value: "fs"
"dist": "15.3", optional distance - the distance between two stations.
If omitted, means the data is missing
Default unit: "distUnit"
"azm": "204.5", Optional angle - the azimuth
If omitted, means the data is missing
Default frontsight unit: "fsAzmUnit", then "angleUnit"
Default backsight unit: "bsAzmUnit", then "angleUnit"
"inc": "-5", Optional angle - the inclination
If omitted, means the data is missing or using station
depths (dive data has no inclination).
Default frontsight unit: "fsIncUnit", then "angleUnit"
Default backsight unit: "bsIncUnit", then "angleUnit"
},
{ ... } Another measurement between from station to the to station
]
},
...
{ The survey must end with a station
"station": "END" (it doesn't have to be called "END", this is just for
illustrative purposes)
}
]
}
]
},
"Mammoth Cave": { Everything inside here is for Mammoth Cave
...
},
...
}
}All numeric data must be entered as strings so that no precision is lost when converting to and from metacave.
The absence of an inclination doesn't mean the inclination is 0. Please don't fill in missing measurements with default values. For instance, if a distance measurement is missing, it means the user didn't enter it in some program, but the program didn't want to discard the other measurements that they had entered. You should ignore incomplete shots and stations when computing loop closure or rendering the cave.
Anywhere (anywhere!) you put a quantity with default units, you can instead override the default unit by typing it after the number, with whitespace between the units and numbers. Examples:
"dist": "4 m" distance is 4 meters even if "distUnit": "ft"
"dist": "5 ft 7 in" distance is 5 feet 7 inches
"dist": "4 in 6 ft 2 m" distance is 4 inches + 6 feet + 2 meters
this is absurd, but programs will be simpler
if they don't have to worry about weird order
or combined unit systems
"azmFsCorrection": "2 grad" frontsight azimuth correction is 2 gradians
"lat": "23 deg 26 min 21 sec" 23° 26′ 21″ (the Tropic of Cancer)
"lrud": ["4", "5", "1", "5 in"] left, right, and up are in default units,
down is 5 inchesYou can add any additional properties you want to JSON objects (the things enclosed in { }).
Programs can ignore additional properties if they want, or visualize them somehow, or allow you to search for shots by metadata, etc.
At the extreme end, programs can embed highly program-specific data - for example Philip Schuhardt and I are working on a way of embedding Cavewhere's scanned note warping data.
The beauty of JSON's flexibility is that other programs will still be able to read all of the core survey data without conversion, even if they don't know how to interpret another program's specific data.
If two programs embed data that has almost the same format but not quite, they might confuse each other - but this can be solved by making an import feature that only interprets the core survey data, and then making the routine that interprets the program-specific data build off of that.
For example, in Fisher Ridge all trips are assigned a number, so we could note that like so:
"trips": [
{
"number": "1",
...
},
{
"number": "2",
...
},
...
]Or say you wanted to note water depth at each station:
"survey": [
{
"station": "W1",
"waterDepth": "2",
...
},
{
"dist": "5",
...
},
{
"station": "W2"",
"waterDepth": "5",
...
},
...
]