UK Caving

TECHNICAL FORUMS => Surveying => Topic started by: SamT on January 25, 2009, 09:40:36 pm

Title: How do I specify 'minutes' in Survex..
Post by: SamT on January 25, 2009, 09:40:36 pm

Ok - trying to get to grips with survex.

The notes I've got are in degrees and minutes (done with a dial)

for example - they are written
Tape    Compass      Clino
3.2m    45deg12'      -15.9deg

etc..

so I've got to use the *units command.

my guess is

Code: [Select]
*units tape meters compass mins  clino degrees
so therefore would i right..

1 2 3.2 45.12 -15.9

 :shrug:
I find the manuals hard work - and Im an IT professional. but getting there.
Title: Re: How do I specify 'minutes' in Survex..
Post by: Cave_Troll on January 26, 2009, 10:42:38 am
i would have guessed converting Minutes into decimal fractions of degrees
Title: Re: How do I specify 'minutes' in Survex..
Post by: graham on January 26, 2009, 11:44:12 am
An interesting question that is certainly not covered by the Survex documentation.

Given that if one specifies "FEET" then the default is decimal feet rather than feet and inches then I suggest that a quick and dirty fix is to as Cave_Troll suggests and do the conversions yourself to decimals of a degree.

A second possibility is to sign up to the Survex email list and pose the question there; doubtless an authoritative answer would then arrive, probably from Olly.
Title: Re: How do I specify 'minutes' in Survex..
Post by: SamT on January 26, 2009, 11:47:48 am
from the manual...

Quote
Example

    *units tape metres

    *units compass backcompass clino backclino grads

    *units dx dy dz 1000 metres ; data given as kilometres

Description

    <quantity> is one of TAPE|LENGTH|COMPASS|BEARING|CLINO|GRADIENT|COUNTER|DEPTH|DECLINATION|X|Y|Z

    Changes current units of all the quantities listed to [<factor>] <unit>. Note that quantities can be expressed either as the instrument (e.g. COMPASS) or the measurement (e.g. BEARING).

    <factor> allows you to easy specify situations such as measuring distance with a diving line knotted every 10cm (*units distance 0.1 metres). If <factor> is omitted it defaults to 1.0. If specified, it must be non-zero.

    Valid units for listed quantities are:

    TAPE, LENGTH, COUNTER, COUNT, DEPTH, dX, dY, dZ in YARDS|FEET|METRIC|METRES|METERS

    CLINO, BACKCLINO, GRADIENT, BACKGRADIENT in DEG|DEGREES|GRADS|MILS|PERCENT|PERCENTAGE

    COMPASS, BACKCOMPASS, BEARING, BACKBEARING, DECLINATION in DEG|DEGREES|GRADS|MILS|MINUTES

    (360 degrees = 400 grads (also known as Mils))

    Defaults are: Metres, Degrees, Degrees respectively.

so Im sure there is no need to do any conversion (on the hundreds of hand written survey notes I have)

Title: Re: How do I specify 'minutes' in Survex..
Post by: graham on January 26, 2009, 11:50:21 am
OK Sam, as I said if you specify "FEET" you get decimal feet, nowhere there does it tell you how to specify feet and inches, does it.
Title: Re: How do I specify 'minutes' in Survex..
Post by: graham on January 26, 2009, 11:51:49 am
Having said that, I'm sure you can get a spreadsheet to do it for you & then just paste the results column into your survex file.
Title: Re: How do I specify 'minutes' in Survex..
Post by: graham on January 26, 2009, 12:00:01 pm
BTW

Larry Fish's Compass will allow you to enter both "feet and inches" and "degrees and minutes". It then stores the info as decimal feet and decimal degrees, however.

As an aside, Compass also allows you to distinguish between the International Foot and the US Survey Foot The former is 0.3048 m and the latter is defined as 1200/3937 m, which is equivalent to 0.30480060960... m. Now, how many of you guys survey to sufficient precision to worry about that?