cavern

SYNOPSIS

cavern [OPTIONS] SURVEY_DATA_FILE…

DESCRIPTION

cavern is the Survex data processing engine.

cavern is a command line tool, but if you’re not a fan of working from the command line you can open unprocessed survey data files with aven and it will run cavern for you, and if successful, display the processed data. If there are any warnings and errors, aven will show a log window with the output with clickable links to open the affected file at the problematic line.

If multiple survey data files are listed on the command line, they are processed in order from left to right. Settings are reset to their defaults before processing each file.

Each SURVEY_DATA_FILE must be unprocessed survey data in a format which Survex supports, either native format (.svx) or Compass format (.mak, .dat or .clp), or Walls format (.wpj or .srv).

Support for Compass .clp was added in Survex 1.4.6; support for Walls was added in Survex 1.4.9.

OPTIONS

-o, --output=OUTPUT

Sets location for output files.

-q, --quiet

Only show a brief summary (--quiet --quiet or -qq will display warnings and errors only).

-s, --no-auxiliary-files

do not create .err file.

-w, --warnings-are-errors

turn warnings into errors.

--log

Send screen output to a .log file.

-v, --3d-version=3D_VERSION

Specify the 3d file format version to output. By default the latest version is written, but you can override this to produce a 3d file which can be read by software which doesn’t understand the latest 3d file format version. Note that any information which the specified format version didn’t support will be omitted.

--help

display short help and exit

--version

output version information and exit

OUTPUT

If there were no errors during processing, cavern produces two output files, with the extensions .3d and .err (unless --no-auxiliary-files is specified in which case only the .3d file is produced).

These two files are always created with their respective extensions. By default they are created in the current directory, with the same base filename as the first SURVEY_DATA_FILE listed on the command line.

E.g. if you process the data file entrance.svx with the command cavern entrance or cavern entrance.svx then the files entrance.3d and entrance.err will be created.

You can change the directory and/or base filename using the --output command line option. If you specify a directory then output files will go there instead of the current directory, but still use the basename of the first SURVEY_DATA_FILE. If you specify a filename which is not a directory (note that it doesn’t need to actually exist as a file) then the directory this file is in is used, and also the basename of the filename is used instead of the basename of the first SURVEY_DATA_FILE.

Details of the output files:

.3d

This is a binary file format containing the adjusted survey data and associated meta data.

.err

This is a text file which contains statistics about each traverse in the survey which is part of a loop. It includes various statistics for each traverse:

Original length

This is the measured length of the traverse (for a “normal” or “diving” survey this is the sum of the tape readings after applying calibration corrections).

Number of legs

The number of survey legs in the traverse

Moved

How much one end of the traverse moved by relative to the other after loop closure

Moved per leg

Moved / Number of legs

Percentage error

(Moved / Original length) as a percentage. This seems to be a popular measure of how good or bad a misclosure is, but it’s a problematic one because a longer traverse will naturally tend to have a lower percentage error so you can’t just compare values between traverses. We recommend using the E, H and V values instead.

Error (E)

This isn’t labelled in the .err file but is the value on a line by itself. In aven it’s the value used by Colour by Error. It is Moved divided by the standard deviation for the traverse based on the standard errors specified for the instruments. This tells us how plausible it is that the misclosure is just due to random errors. It is a number of standard deviations, so the 68-95-99.7 rule applies - e.g. approximately 99.7% of traverses should have a value of 3.0 or less (assuming the specified instrument standard deviations are realistic).

Horizontal Error (H)

This is like E but only considers the horizontal component. In aven it’s the value used by Colour by Horizontal Error. You can identify suspect traverses by looking at E and then compare H and V to see what sort of blunder might explain the misclosure. For example, if H is small but V is large it could be a clino reading or plumb with an incorrect sign, or a tape blunder on a plumbed leg; if H is large but V is small it could be a compass blunder, or a tape blunder of a nearly-flat leg.

Vertical Error (V)

This is like E but only considers the vertical component. In aven it’s the value used by Colour by Vertical Error.

This information is now also present in the .3d file so you can view the survey coloured by these errors, but the .err file can still be useful as you can sort it using sorterr to get a ranked list of the sections of survey with the worst misclosure errors.

Cavern also reports a range of statistics at the end of a successful run:

• The highest and lowest stations and the height difference between them

• The East-West and North-South ranges, and the Northernmost, Southernmost, Easternmost, and Westernmost stations.

• The total length of the survey (before and after adjustment). This total excludes survey legs flagged as SURFACE, DUPLICATE, or SPLAY.

• The number of stations and legs. Note that a *equate is counted as a leg in this statistic.

• The number of each size of node in the network (where size is number of connections to a station) i.e. a one node is the end of a dead-end traverse, a two-node is a typical station in the middle of a traverse, a three-node is a T-junction etc.

• How long the processing took and how much CPU time was used.

If you successfully processed your data by loading it into aven then you can see this log output by using File->Show Log (also available as an icon in the toolbar).

Error Messages

There are many different error messages that you can get when processing data. Along with the error message, a location is reported. For an error like “file not found” this only reports the filename, but usually it will give the filename and line number of the offending line, and in many cases also an offset or span within the line.

The format of the location data follows that used by the GCC compiler so if your text editor can parse errors from GCC then you should be able to set it to allow you to jump to the file and line of each error.

One common cause of errors and warnings are typing mistakes. Another is your survey data not being all attached to fixed points (which is a warning since Survex 1.4.10, but was an error prior to this; in this situation, Survex will list at least one station in each piece of survey data which is not connected).

We try to make error and warning messages self-explanatory, but welcome feedback on cases where you get a message which seems unclear.

Generally you want to look at the first reported error first as there can be a cascade effect where one error triggers another. Cavern will stop after more than 50 errors. This usually indicates something like the incorrect data order being specified and deluging the user with error messages in such cases usually makes the actual problem less clear.