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Paperless Survey

Here are some ideas that are developing as I try out our DistoX and PocketTopo with Therion. (See http://therion.speleo.sk/workflow.php and follow the relevant links) This page assumes you have some familiarity with DistoX, PocketTopo and the contents of the respective manuals.

Disclaimer: I have no experience or qualifications in paperless cave surveying. I bought a DistoX, borrowed a PDA, and now I toss them into my cave bag and take them to the furtherest reaches of our current exploits. We are stumbling along with the process, and so far it's working out OK. These are some rules that I'm making up for myself to make sure it really does live up to the promise of being faster and easier than scratching on a piece of paper, even if we do pick up 10x more detail…

I welcome any insights you may have. Add them to this page.

DistoX & PocketTopo > Therion

For PocketTopo 1.22, 1.34-1.36 and Therion 5.3+

Some ideas to minimise confusion and data loss.

DistoX and Survey Sequence

DistoX usage in general

DistoX with PDA

  1. define passage plan shape generally along the line where the floor meets the wall generally in the direction the survey is proceeding. This could extend to picking up the ceiling if it is significantly different to the floor. (The 'to station' for these shots would be a - (a dash) in Therion – when implemented)
  2. define important plan features (edge of water, pits, speleothems, rigging or large rocks etc). (The 'to station' for these shots shots would be a . ( a dot) in Therion– when implemented)
  3. define passage extended elevation shape (long section) shape. Pick up general changes in floor and ceiling gradient or steps from the previous station towards the next station (unless already picked up). (The 'to station' for these shots would be a - (a dash) in Therion – when implemented)
  4. define important extended elevation features (ledges, pits, speleothems, rigging or large rocks etc). (The 'to station' for these shots shots would be a . ( a dot) in Therion– when implemented)
  5. define cross section if you haven’t already. ie for a quadrilateral section shape, this would be the four corners. For an arbitrary shape take maybe 8 shots around the passage section. (The 'to station' for these shots would be a - (a dash) in Therion – when implemented)

PDA Booking

PocketTopo Key Points

The key points to note are;
1. Ensure all files that contain surveys that are connected to each other are in the same folder. PocketTopo will then display the centrelines of all these surveys in the background of the current survey and sketch. Do not keep any copies or other files in that folder.

2. Main reasons to start a new file are when a new days survey is started, a new survey is starting in a different location, or if the plan or elevation centrelines start overlapping (causing the sketching to become difficult). This way the centrelines of other surveys remain visible and only the sketches of the currently open file can be seen (reduces confusion). It also reduces the chance of accidentally changing the data from a previous days survey.

The definition of 'series' in the next two sections is quite restrictive, and in practice I ignore it, without I think, many consequences.

PocketTopo Station Numbering
PocketTopo Survey Loops and Connections

I break these rules (for numbering and series) regularly, and don't seem to suffer too many consequences. PocketTopo is getting better (1.36) but is perhaps helpful to know where it has come from.

How to cross a survey 'series' How to join up all the survey 'series'

This is why series 4 (yellow) ends when it gets to station 1.4, and continues as series 5. Similarly for series 7 (green) to series 12, and series 8 (purple) to series 9.

PocketTopo on Trimble Recon

left soft button restores PocketTopo
right soft button restores File Explorer

Now this next bit has been confusing the hell out of me. I don't think I've got it right yet, but anyway it might work something like this…

Data Transfer from PocketTopo to Therion

You're going to need to make sure your PDA can talk to your big computer. Assuming a Trimble Recon and Windows XP, you'll need to download ActiveSync. If using Vista or Windows 7 then your computer will probably need internet access the first time you connect the PDA so it can download the files automatically.

This next bit generally encapsulates getting to step 4 'insert background images' of my drawing checklist when you are 'paperless surveying', and includes examples that follow my own evolving naming convention. You can use your own names…

This saves a lot of typing. See Drawing Checklist > Scrap eg

    station-names AA []
    

You can change the prefix or suffix (or both) sequentially by inserting new station-names statements throughout the file.

Scraps drawn over the xvi files will automatically record the 'PocketTopo' name of survey stations when they are drawn. Get Therion to add the prefix and suffix (@SurveyName) to each station automatically by adding the following options to each SCRAP.

-station-names <prefix> @<SurveyName> -author <year> ”<AuthorName>” -copyright <year> “NZSS”

eg

  \ -station-names AA @AA-EntranceSeries -author 2009.11.20 "B Mutton" -copyright 2009 "NZSS"

This approach requires some modification when a scrap is comprised of stations with differing prefixes or suffixes. First, draw the stations in the scrap with the XTherion drawing editor, close and save the file, then open it with a text editor. Now you can add station-names statements sequentially with the revise statement. eg

  revise AA-EntrancePlan-s1 -station-names AA @AA-EntranceSeries 
  point 1063.22503937 587.2462992 station -name 9.4 #Therion will see this as AA9.4@AA-EntranceSeries
  revise AA-EntrancePlan-s1 -station-names JH @[] # [] to indicate no suffix
  point 1140.29503937 519.4162992 station -name 9.3@jh1 #Therion will see this as JH9.3@jh1

Now you can compile to test it works, then open the file with XTherion and continue drawing in the normal way.

Sketch inserting and scaling tip

If, in the Insert background image open dialog you cannot find your exported PocketTopo files, then in the 'files of type' box select 'PocketTopo Therion export (*.txt)

Now once you have selected the file and closed the dialog, Xtherion will ask you for the xvi properties. The defaults are; scale 1:200 resolution 200 dpi grid 1m

These seem to be fine for small cave passage, but for larger cave passages a scale of 1:500, 100 dpi seems to give a better zoom range in Xtherion. Also I have a habit of drawing my pencil sketches of projected elevations at 1:500. Sometimes I insert the extended elevation xvi and scanned pencil sketch into the same file. Matching scales and dpi values gives a better result.

CAUTIONS

Troubleshooting Data Transfer

We've been (early to mid 2010) having trouble with frequent communications blackouts between our distoX and Trimble Recon pda (tentatively mostly resolved early 2011). The distoX usually indicates it has a blue-tooth connection (the icon flashes on and off) but the data transfer does not proceed. It can take some minutes before data transfer re-commences. The battery levels in both devices appear to be 'full'.

Here is what we have tried… compared with the degree of success…
Maintain the devices within 1m of each other and wait Somewhat successful, definitely better than if they are 5m apart
Gently thrust them towards and away from each other while humming a mantra As above
Avoid passages with dimension less than 1.5m, especially if the walls are wet Usually works
In PocketTopo toggle Connect/Disconnect/Auto Sometimes successful
Turn distoX off and shut down PocketTopo. Start PocketTopo and turn distoX on about 1 sec later Most successful?
In PocketTopo save the file Sometimes successful
Change distoX batteries well before you need to In combination with the above seems to be most successful, even though Beat assures me that this should not affect performance. We suspect that the frequency of spurious erroneous distance measurements increases when the batteries are getting low, particularly the last 1000 or so shots.

Tip: Well before your batteries die, pre calibrate a fresh set in a comfortable location during fine weather, mark the ends (see page 1 of http://paperless.bheeb.ch/download/DistoXAccuracyPrecautions.pdf ) and write the date of calibration on the batteries. Save the calibration file with the same date, and take the file and batteries with you from now on. When the batteries die in the middle of a survey, it's now a simple matter to change the batteries (if the cave is dry) and transfer the new calibration to the distoX.


We corrected a problem whereby the pda was not recognising the backup CF flash card because it was in the 'wrong' slot. Resolving this improved the above situation, but did not completely fix it.

Any further enlightenment will be gratefully received.

Here is Beat's suggested progression for restoring stalled communication. Keep moving down the list until the data transfers. Note that pocketTopo tries to connect at 5 sec intervals, so don't be too impatient. If your devices have been working happily together, then you almost certainly only need to try the first two options;

  1. Normally it suffices to switch off the Disto for a few seconds.
  2. The next step would be to restart (warm boot) the PDA.

If this does not help then we are heading towards a troubleshooting approach;

  1. Check the disto is not in 'silent mode' (A small 0 displayed at top centre of screen -Toggle this on and off by pressing AREA, AREA, REF, REF, CLR) Activating silent mode prevents any currently stored data from ever being transferred, so be careful. If you don't have the small 0 displayed, try this option last.
  2. Try to connect the Disto from the Bluetooth manager. The Bluetooth icon on the Disto should flash. This means the pda can 'see' the disto signal.
  3. Disconnect from the manager and try to connect from PocketTopo (Menu:Bluetooth:connect). If it fails check the Port setting in PocketTopo matches the port setting for the disto in the Bluetooth manager. If you have more than one disto, each one seems to need it's own unique port setting.
  4. If the connection works but no data is transferred, try to switch the Disto to calibration mode using the commands in the calibration menu. If calibration mode can be switched, this confirms data can be sent from the pda to the disto, and so the lack of communication in the other direction is indeed an anomaly. I had this situation with lots of data stored, and toggling silent mode on and off resolved it. Only took 6 weeks to figure it out :-? )

Troubleshooting Erroneous Measurements

This is more a warning to be observant, rather that troubleshooting as such.

Distance

We've noticed that spurious distance measurements are more common than we would like, maybe 2% of shots?? All of the ones we have noticed are more than the actual distance measured, usually by more than a factor of 2 or 3 (a typical case would be a distance of about 10m measured as either ~50m or ~80m for a sequence of 5 shots, with the latter two pointing at a completely different target - and in a passage where we could see no more than 15m), but there was one case in a wide open passage where ~15m was measured as 25m (and we are sure we were not missing the target).

This can manifest a little bit like the sticking of compass or clino (see below) except that the erroneous measurements are usually not identical - so leading you to believe it is a normal measurement discrepancy. One explanation is that the laser is bouncing off nearby walls. This is certainly sometimes the case, although I can only remember one instance where this was happening on a repeatable basis. Moving the target slightly can solve this issue.
I suspect this problem is more frequent when the batteries are getting low, down to their last 1000 or so shots (although Beat has assured me that this is unlikely). Note that the distoX battery indicator only deviates from 100% when there are perhaps 10 or 20 shots left (when you are using lithium batteries as recommended) so unfortunately it is not a useful indication of battery health.

Compass and Clino

Both the compass and clino sensors seem to stick sometimes. If you see that the last several compass or clino readings are identical regardless of the orientation of the distoX, then you can be sure they have 'stuck'. A very gentle tap with your finger usually fixes this (remember it is a delicate device).
Ferrous objects and magnetic fields will affect the compass of course. Take care not to use the distoX within say 300mm of your light, SRT gear, bolts etc.