Backsights (and lava caves)

[Sergey Sorokin]

Hello!

P A Hill & E V Goodall wrote:
> Bill Frantz wrote:
> > My current idea for a true solution to this problem is a new instrument.
> > It would hold two laser pointers, and sit on the station.  (Short tripods
> > might be used as stations with this method.  You would align one laser on
> > the previous station, and the other on the next and read the turn angle off
> > the instrument.  With 3 tripods, two reflectors, and the instrument the
> > survey would proceed by:

>  From what I understand (which isn't much) is that today, you'll still
> plane plane table surveys when surveying a 'site', maybe for creating a bit
> of detailed togography for a geological, hydrological or even an
> archeological study.  One person stays at the table turning angles and
> shooting to one or more others who walk about on the site picking
> interesting points, thus creating a detailed map of the visible site.

The problem with this method, when applied to caves, is that errors in
defining directions will add while you process with survey. That is if
you have error of 1 degree at each measurement than you may have error
of 10 degrees after 10 stations. It is not the problem with 'site'
survey since in the described situation person get all the readings from
single position (or may be move but not that much as in cave). So, I
suppose that in order to get reasonable results it will be required to
measure angles with quite high precision.

WBR,
Sergey.