SexyTopo is an app for surveying caves and underground spaces. It is designed to work with an electronic measuring device which the surveyor uses to measure out survey legs. It is also possible (though significantly less convenient) to use SexyTopo as a tool for manual entry of survey data.
SexyTopo runs on Android devices (the newer/more powerful the better). For obvious reasons a water- and dust-proof device is recommended. Both phones and tablets are supported. It is possible to control SexyTopo with finger movements but it is designed for use with a stylus.
A full description of surveying is beyond the scope of this document but this is a brief overview of how to survey with SexyTopo.
Surveying consists of moving through the cave along a series of locations known as stations. These points are connected together through measurements known as legs (or shots in some countries). This collection of stations and legs make up the skeleton of the survey, or centreline. The survey may also contain legs that do not connect to a station but help measure out the shape of the cave (known as splays).
Typically, a surveyor will start at a station and take several splays (ideally the job will be split between at least one caver taking the measurements and another piloting SexyTopo). A common method is to use the LRUD mnemonic and do Left, Right, Up and Down splays from the station, but additional splays are often useful, especially in complex parts of the cave. Then the surveyor will look for the next station. You can instruct SexyTopo to create a new station (rather than a splay) by repeating a measurement three times. If the readings are sufficiently close, a new station is added. The surveyor then updates the sketches of the plan and profile on the graph screens, before moving to the new station and repeating the process.
Legs are added to the survey at the active station. By default the active station is the newest station added to the survey. In the standard order of things (as described above) the active station should automatically be the one you want, but you will want to change it in case of a mistake or to make a branch in the cave. For example, you may have created a new station but forgotten to take splays at the station before. Here you can select the previous station as the active station, take any required splays, then set the new station as the active station.
Branches are just as easy to add. Select the station you wish to branch off as the active station, and then create a new station as before.
SexyTopo supports a wide range of cave surveying instruments including DistoX, DistoX BLE, CavwayX1, Bric4, Bric5, SAP5, SAP6, FCL, and DiscoX.
To connect an instrument, open the Device menu and select Connect. The instrument connection page guides you through the pairing and connection process. A console at the bottom displays status messages from the device.
The compass and clinometer in a surveying instrument need calibrating to give accurate readings.
SexyTopo can calibrate the DistoX (A3), DistoX2 (X310) and DistoX BLE. Connect to the instrument, then choose Calibration… from the Instrument menu to open the Calibration view.
Take at least 56 readings: 4 rolls in each of 14 directions, pointing from the centre of a cube to its 6 faces and 8 corners. Keep the laser on the same point while rolling. The directions can be taken in any order, as long as each direction's rolls are taken together. Extra readings are fine: every reading is used.
After calibrating, it is worth checking the instrument by taking a few shots between two fixed points in both directions: the forward and back readings should agree closely.
Save and Load store the set of calibration readings in a file. This lets you keep a record of a calibration, or come back to it later.
SexyTopo uses a linear calibration algorithm for the original DistoX and a non-linear one for the DistoX2 and DistoX BLE. This can be overridden in Settings → Instruments → Disto-X calibration algorithm.
Some instruments (such as the SAP6 and CavwayX1) calibrate themselves on the device. For these, SexyTopo provides commands in the Instrument menu to put the device into and out of calibration mode; follow the instrument's own documentation for the calibration procedure.
This is a tabular view of the collected data. It can be accessed through the first icon on the Action Bar. SexyTopo is designed with the intention that most interaction should be through the sketch screens but it is occasionally useful to check the raw data.
There are onscreen buttons for manually inputting data: there are two buttons for adding new stations and splays.
Tapping on a table row opens the view/edit dialog for that row, where the data can be seen in detail and updated if necessary.
Long-pressing on a table row or selecting a station in the graph views activates a unified context menu.
The sketch views (plan and extended elevation) can be accessed through buttons on the Action Bar at the top of the screen. These show a projection of the calculated survey on a canvas so that a sketch of the cave can be drawn on top. The plan view is an intuitive map of the cave whilst the extended elevation is an "unrolled" view of the vertical layout of the cave.
A selection of sketching tools are provided via a toolbar at the bottom of the screen:
A legend at the bottom right of the view provides a scale bar, basic stats, and a reminder of the survey name.
The plan view can optionally display a compass in the corner of the screen, showing the direction of North based on your device's orientation sensor. This can be toggled on or off via the quick settings menu (the display menu icon on the toolbar).
A cross-section shows the shape of the passage at a station, drawn from that station's splays. It appears on the sketch as a small framed view, joined to its station by a dashed line, and a marker across the station shows which way the section faces. Each station can have one cross-section in the plan and one in the elevation, and the two are independent of each other.
Select a station to open the context menu, choose Cross-Section, then the kind of section you want, and tap where on the sketch it should go.
How large cross-sections are drawn relative to the survey can be set separately for the plan and the elevation under Settings → Survey.
The 3D view provides an interactive three-dimensional view of the survey skeleton. It can be accessed from the View menu.
The view shows survey legs, and stations rendered in 3D space. Controls:
SexyTopo provides several menus accessible from the Action Bar ("hamburger" button for extended menus) for managing surveys, configuring behaviour, and accessing various views and tools.
Additionally, the View menu provides access to the 3D view (see below).
Controls how measurements from the instrument are interpreted:
Opens the settings screen for configuring app preferences, display options, and behaviour. Notable settings include:
A unified context menu is available from the table view and graph views. Long-press a table row or select a station in the sketch views to access it. The menu is organized into submenus with options depending on what's selected.
In elevation view, controls which direction to draw the leg:
Jump to the selected station in different views:
The Trip view (accessible from View → Trip) records metadata about the current surveying trip. This information is saved with the survey and can be useful for record-keeping and for export to other survey formats.
Each trip has a survey date (when the survey data was collected) and an optional exploration date (when the passage was first explored, if different). Tap the date fields or calendar icons to select dates using a date picker. By default the exploration date is linked to the survey date; uncheck the "Linked" checkbox to set a separate exploration date, or use the Clear button to remove it.
Records which instrument was used for the trip. If an instrument is currently connected, SexyTopo can auto-fill this field using the "Get Instrument" button.
You can record the members of the survey team and their roles. Tap "Add" to add a team member with a name and one or more roles.
SexyTopo remembers caver names you have entered previously and offers them as suggestions when adding new team members, so you don't have to type the same names each trip. Tap a team member to edit their details, or use the delete button to remove them.
A free-text field for any notes about the trip.
SexyTopo stores survey data on your device and provides various options for managing survey files through the File menu.
Surveys are saved in their own folder (directory) on your device. A survey may contain several files, including survey data files (measurements, stations, legs), sketch data (plan and elevation drawings), and metadata (trip information, comments).
After creating a survey (File -> New Survey), it is recommended to save it. Previous versions of SexyTopo handled this for you, but Android now requires the user to manage the file handling. When saving a file for the first time, SexyTopo opens a file selector for you to choose a folder to save it in. Important: you almost certainly want to create a new folder to save the survey in rather than selecting an existing one (otherwise both you and SexyTopo will get confused, and it might overwrite data you want to keep).
SexyTopo attempts to default the save location to a folder in Documents/SexyTopo/Surveys, but this doesn't work on all devices, and you are free to choose your own folder structure. At the time of writing, SexyTopo doesn't care about where linked surveys are saved, but this may change in the future.
To manage the complexity of anything other than very small caves, you will likely need to break the overall survey of a cave into smaller individual surveys. This provides several advantages, including managing the cognitive load of understanding how the survey fits together, improving rendering performance in SexyTopo, and aligning with the standard workflow of cave drawing packages such as Therion.
SexyTopo provides UI controls such as fading out or hiding the parts of the survey not currently being worked on. This is particularly helpful for dealing with extended overlapping sections of cave passage, and starting a new linked survey is the recommended way of handling this kind of continuation.
To start a new linked survey, select a station from the context menu and select Survey → Start New Survey Here. There is also an option to link to an existing survey and to unlink a survey.
SexyTopo can exchange data with other cave surveying software through import and export functions.
To import survey data from other software, select an action from File → Import in the menu.
Export allows you to save your survey in various formats for use with other software, sharing, or publishing. Select File → Export and choose your desired format.
The exported file or folder will be produced in an Exported folder inside your survey folder with a name of the export selected (e.g. Exported/therion), unless otherwise specificied in Settings.
In typical caver fashion, you've probably cajoled someone into lending you their shiny measuring device, completely failed to have a practice with it and assumed you'd just wing it. Now you've found yourself in the sharp end of some crappy hole somewhere realising that you have no idea why your surveying kit doesn't work. Luckily you've found SexyTopo has a help file and you're desperately trying to scan through it looking for some hope. First of all, don't panic...
Check the following are true: Bluetooth is turned on on the device, the device is paired with your instrument and the Connect switch is on. Check the on-screen console on the Instrument page: it may show an error message or give some clue as to what is wrong.
If that fails, try turning your instrument off and back on. Try unpairing and re-pairing, or even turning Bluetooth off and on again. It shouldn't make a difference but you could kill SexyTopo and reopen it. Check you haven't paired with the wrong device (the Unpair dialog shows which devices are paired).
For DistoX devices: if all else fails a factory reset may be necessary. Press CLEAR, FUNC and MEM (the latter has a floppy disk or save icon) for five seconds. Note that this is an option of last resort and requires recalibrating the device.
Your instrument may need calibrating. Consult your instrument's documentation for calibration procedures. Some devices (such as DistoX) can be calibrated within SexyTopo; see Calibration.