Simulator user guide

01Before you start

The simulator is an educational tool: it shows why the scent available to the dog may not coincide with the missing person's physical route. It runs in the browser, with no account and nothing to install. A laptop or a wide monitor is recommended (the interface has three columns), but it also works on tablets and phones: there the left panel opens from the ☰ button and the right one from the ⚙ button, both in the top bar.

The chain you follow is always the same:

1. the person's route
2. scent emission
3. environment and weather
4. scent field
5. sampling by the dog
6. the dog's behaviour
7. replay and analysis

02The start screen

The page opens on the start screen: an animated backdrop with a route, scent particles carried by the wind and a working dog. From here you have two main entry points and a few shortcuts.

Start a new scenario

Opens the six-step wizard (environment, weather, route, trail age, dog team, summary). The map appears only at the end, when you press “Start the simulation”; if you close the wizard with X or Esc, you stay on the start screen.

Use a demonstration scenario

Opens the chooser with all the demonstration scenarios; pick one and the simulation starts straight away, with the dog at the beginning of the search.

The row of figures

The number of environments, demonstration scenarios, weather presets and dog profiles is computed from the application. Each figure opens the matching entry point: environments open the wizard at step 1, scenarios open the chooser, weather presets open step 2, dog profiles step 5.

The version badge

The current version and stage (beta). While the stage is beta, features and displayed values may still change.

User guide

The link under the buttons leads to this page; the same link sits in the top bar of the page and in the “Help” window.

Your scenarios are saved locally, in this browser (not on a server) and can be exported as a JSON file; see Saving, export and import.

03Demonstration scenarios

Each demonstration scenario illustrates one principle: a ready-made environment, matching weather, a route and a trail age chosen so that the effect is visible. The chooser shows them as numbered cards with the name and the principle; the search field filters by text, and the first card is marked as the recommended start.

The same scenarios are always available from the Scenario panel (left), drop-down list Demonstration scenarios: the principle of the chosen scenario appears below the list. The Start screen button in the top bar takes you back to the start screen at any time without losing the scenario in memory.

The list of scenarios and the principle of each

04A new scenario, step by step

The wizard builds a complete scenario in six steps. The list of steps stays visible at the top of the window; Back and Continue move between steps, and the last step shows Start the simulation.

1. Choose the environment. Name the scenario and pick a generated environment: Urban, Park, Forest, Field, Urban + forest, Hills + valley or Custom (an empty world you build yourself in Edit mode). Generated environments automatically receive street furniture (lamp posts, benches, bins, kerbside trees).
2. Configure the weather. A Weather preset (from warm and dry to snow and fog), then Wind speed and Wind direction. Automatic wind evolution decides whether the direction stays constant, changes while the person is still walking, changes while the trail ages, or both; the changes appear as events on the timeline.
3. Choose the person's route. Either I pick a predefined route (a Route variant specific to the environment and a Route length between 30 and 3000 m; for long routes the map grows automatically and receives new terrain in the style of the environment), or I draw the route on the map: after starting, the application opens in Edit mode with the “Person's route” tool active.
4. Set the trail age. How much time passes between the person's departure and the dog's start: from 5 minutes to 24 hours. Ageing is not a simple fade: the scent is actually evolved in time (transport, diffusion, deposition, re-emission, rain, decay).
5. Configure the dog team. Dog profile (Beginner, Intermediate, Advanced) and Leash length (2–15 m). The profiles are sensitivity presets of the simulation, not “scientifically exact” modes.
6. Start the simulation. The summary shows the environment, route, weather, trail age and team; “Start the simulation” loads the scenario, opens it in Simulate mode and brings it to the moment the dog starts.

05The interface in Simulate mode

Once started, the screen has four areas: the top bar, the Scenario panel on the left, the map in the centre and the tabbed panels on the right. The timeline sits under the map.

The top bar

Start screen

Back to the start screen (stops playback, replay, presentation and full screen). The scenario stays in memory.

Edit / Simulate

The two working modes. In Edit you build the environment and the route; in Simulate you run time and watch the scent and the dog. Switching to Simulate after a route change restarts the simulation.

Instructor view / The dog's perspective / Split screen

The instructor view shows everything: the route, the person, the scent cloud. The dog's perspective hides the route, the person and the global cloud and shows only the information from the area investigated by the nose. Split screen puts the two side by side.

Exercise ▾

Starts a normal or a blind exercise and, at the end, shows the replay; see Exercises, replay and analysis.

View replay

Enters the replay of what has been recorded so far (the dog's and handler's positions, the scent field), with its own time cursor.

Presentation mode

Large labels and a reduced interface, for a projector; see Presentation mode.

Full screen

The application fills the screen; Esc returns.

? Help

The in-app help window: short explanations by topic (particles, wind, buildings, rain, sun, surfaces, the dog's perspective, how to create an exercise, limitations), the text “About the accuracy of the simulation”, the engine version and the scenario seed, plus the link to this guide.

The Scenario panel (left)

Scenario name

Shown in the list of saved scenarios and used for the exported file name.

New scenario / Load scenario

Opens the wizard, respectively the library of scenarios saved in this browser (with Load and Delete for each).

Demonstration scenarios

The drop-down list with all demonstration scenarios; the principle of the chosen one appears below.

Save scenario / Duplicate / Reset

Saving is local (browser). Duplicating creates a copy under another name. Reset returns the scenario to its initial state.

Export JSON / Import JSON

The file name.sarsim.json holds the whole scenario: environment, route, weather, events, dog, seed and engine version. Import happens in your browser; nothing is sent to a server.

Simulation seed

Makes the scenario reproducible (turbulence, gusts, the dog's decisions). The same seed on the same scenario gives the same simulation.

Build the scenario / Tools / Import GPS track

Below the Scenario section come the object palette, the map tools and the GPS import buttons (prepared for a future version). A click on a palette object switches to Edit mode automatically; details in Editing.

The map

The corner display (HUD)

Time elapsed since the person left and the time of day; the wind (km/h, m/s and the direction it blows from); temperature and humidity; the time the dog starts; when relevant, the “Exercise” badge.

The legend

Relative availability of target scent: Very low, Low, Medium, High, plus the distinction Airborne scent / Surface-bound scent. Positions and intensities are educational approximations.

The + − ⊞ buttons

Zoom in, zoom out, fit the world. Pan the map with the right or middle mouse button held (or with Space held), zoom with the wheel or two fingers.

Numbered pins and “Observations on the map”

In educational mode the application places pins on points of interest (the side street the scent entered, the turbulence zone, the intersection, shade, a hot surface, rain, the place where the person stopped). The balloon appears on hover, and the “Observations on the map” strip under the map lists them; the arrow on its right collapses it. Pins appear only in Simulate mode, in the instructor view, once time has started to run.

The label under the map

The missing person's status at the current moment (for example “The person continues” or a stop).

The tabs on the right

Properties (the selected object or, with nothing selected, the missing person and their route), Weather, Scent, Dog and Analysis. Each has its own section below.

06Timeline and events

The timeline under the map controls simulation time. The displayed time is the time elapsed since the person left; next to it is the time of day (it matters for the sun and for surface temperatures).

▶ Play / ⏸ Pause / ⏹ Stop / ↺ Restart

Play, pause, stop and restart from zero. Space toggles playback (when the dog is not under manual control).

+1 s / +10 s / +10 min

Advance in fixed steps, useful to age the trail quickly or to analyse frame by frame.

Speed

From 0.25× to 60×. At high speeds the engine uses larger time steps so that a trail of several hours can run in seconds.

⇥ Start dog

Jumps straight to the moment the dog starts (the trail age has already passed).

+ Event

Schedules a change at a given moment: the event type, the moment (hh:mm:ss since departure) and the transition; depending on the type, the new wind speed and direction, a gust intensity, the temperature, the precipitation type, the weather afterwards, cloud cover, sun intensity or humidity. Events generated by “Automatic wind evolution” are marked automatic and can be edited.

Save moment / Event list

A saved moment (checkpoint) can be restored or compared from the Analysis panel. The event list shows all scheduled changes, with Edit and Delete.

The timeline bar

Drag the cursor to move in time; the marks show the dog's start and the events.

07Editing: environment and route

In Edit mode you work with the Build the scenario and Tools sections of the left panel, while the Properties tab shows the selected object. A click on a palette object or on “Draw the route” switches to Edit mode by itself.

Build the scenario

The palette has three categories: Infrastructure (building, house, apartment block, warehouse, wooden, concrete or wrought-iron fences, hedge, wall, street, alley, sidewalk, footbridge, parking, tunnel, underpass, bus stop), Natural terrain (grass, soil, sand, forest, vegetation, bush, trees, forest path, water, rock, scree, snow, hill and valley) and Urban objects (street furniture). Click an object, then click the map to place it. Here you also choose the Base surface of the world and its size (World width, World height, 100–1500 m; 1 unit = 1 metre).

Tools

Select / move

Click an object to select it; drag to move it; the handles resize or rotate it.

Person's route

Click the map for each point of the route, double-click or Enter to finish. Each point then receives, in Properties, the movement mode until the next point (walking, running, standing still, sitting, getting into or out of a vehicle) and a dwell time in seconds.

Dog position

Click the map to place the team (dog and handler) at the start of the search.

Scent probe

Click the map to see, in the Scent tab, what is available at that point.

Cross-section

Drag an A–B line across the map; the chart in the Scent tab shows the scent along it.

Add an observation

Places an instructor note on the map (see Analysis).

Properties

For an object: Rotation (and the Rotate 15° button), Height, Material (concrete, brick, glass, metal, wood), Porosity for fences and vegetation, Canopy density and Canopy opening above the path for forests and paths, Surface, Flow direction and Flow speed for water, Maximum elevation for relief, plus the computed surface temperature, Duplicate and Delete. For the missing person (nothing selected): Movement speed, Relative scent source intensity, Departure time, Trail age (or a custom number of minutes) and the Route and stops section, with the list of points, Redraw the route, Delete the route and Desired length + Adjust the route: shortening cuts the route to the requested length (the destination keeps its stop), lengthening adds a continuation with turns over passable terrain, avoiding buildings and deep water, and the map grows if needed.

What each object does to the scent: walls, buildings and rocks are barriers with a wind-sheltered side; a concrete fence behaves like a wall, an iron fence lets the air through, a hedge is vegetation; a street means building shade, traffic and pedestrians; a bridge lets the scent fall onto the water or street below; a bus stop is a shelter that concentrates; flowing water carries the scent downstream; snow absorbs scent best; hills and valleys produce slope currents. Every new route keeps a gap of at least 30 m between non-adjacent legs so that the trails do not overlap.

08The Weather panel

The weather can be changed at any time, even during playback. The wind direction is the one it blows from (0° = north); the speed is shown in km/h and m/s.

Wind

Direction, Speed, Automatic evolution (the direction-change profile), Variability (slowly rotates the direction), Gusts (temporary speed increases), Turbulence (more random spreading), Gust now and Scheduled change… (opens an event on the timeline).

Conditions

Quick presets (the same presets as in the wizard), Air temperature, Humidity, Weather (clear, partly cloudy, overcast, fog, drizzle, light rain, moderate rain, heavy rain, snow, blizzard), Precipitation (manual, experimental), Initial snow cover and Initial surface wetness.

Sun

Time of day (departure), Sun position (automatic from the hour or a manual azimuth), Sun intensity and Cloud cover. Exposed surfaces warm up differently (asphalt a lot, grass little); hot surfaces lift the scent by convection, shade keeps it near the ground.

Traffic and pedestrians

Traffic (Off, Low, Medium, Heavy) follows the streets automatically: the wheels and the airflow under the vehicles lift a small fraction of the scent deposited on the asphalt and the wake carries it locally, without erasing the trail. Pedestrians (None, Few, Normal, Crowded) can become, with Simulate scent contamination, sources of foreign scent tracked separately from the missing person's scent.

Rain washes airborne scent towards the ground, increases deposition, wets the surfaces and redistributes part of the deposited scent (runoff): it does not erase all scent, but moves and dilutes it. Wet surfaces retain more and re-emit less until the sun warms them.

09The Scent panel

Here you choose how the scent field is drawn and which layers are visible, adjust the simulation quality and use the two measuring instruments.

Scent visualisation

Particles (abstract carriers of airborne scent), Scent cloud, Heat map, Ground deposition, Airborne, Combined and Concentration isolines. The colours show only the relative availability of the target scent.

Layers

Toggles for the missing person, their route, particles, heat map, ground scent, airborne scent, wind, turbulence, thermal currents, ground temperature, sun/shade, rain, water/runoff, pedestrians, traffic, dog, dog track, handler, buildings, contamination and isolines.

Simulation quality

Low (3,000 particles, 4 m grid), Normal (9,000, 2 m), High (18,000, 1.5 m), Ultra (35,000, 1 m). On a slow computer choose Low: the number of simulated particles is independent of how many are drawn.

Simulation profile

Educational (emphasises cause–effect relations), Conservative realistic (less exaggerated visual motion, more uncertainty in the dog's signal), Enhanced visualisation (higher contrast for a projector). They are presentation presets, not claims of accuracy.

Scent probe

Click the map: the relative values at that point (airborne, on the ground, local wind direction).

Scent cross-section

Draw the A–B line: the chart shows the availability along the line. The peak may be shifted away from the physical route, exactly the phenomenon the simulator illustrates.

Camera and display

Follow the dog, Orient to the dog (the map rotates with the dog's heading; the manual-control keys become relative to the dog), Educational mode (explanations on the map) and Free camera (fit the world).

10The Dog panel and the dog's behaviour

The simulated dog does not “see” the scent map: it samples locally, around the nose, and decides from the relative signal it perceives. The panel has four sections.

Dog team

Place the team on the map (switches to Edit mode with the “Dog position” tool), Jump to the start of the search, Leash length (the dog cannot get further from the handler than the leash) and Manual control: a click on the map = destination, WASD or the arrow keys = movement, on a touch screen tap the destination. The handler follows the dog.

Olfactory signal

The current state, the chart of the relative signal over a Window of 30, 60 or 120 s, the trend (rising, stable, falling) and statistics. The signal is normalised to what the dog has perceived so far, not to an absolute scale.

Dog profile

Beginner, Intermediate, Advanced or Custom, with the parameters Relative detection threshold, Sampling frequency, Reaction latency, Persistence after losing the signal, Exploration tendency, Gradient sensitivity, Wind influence, Variability, Working speed. Changing any parameter switches the profile to Custom. They are simulation parameters, not measured biological values.

States

The list of states with the current one highlighted; they are abstractions of the simulation, not behavioural diagnoses.

What the states mean

• WaitingThe trail age has not passed yet; the dog has not started.
• SearchingAt the start it makes an orientation circle (a “360”) to pick its direction, then looks for signal.
• FollowingIt has a strong signal in the direction of travel and advances along the scent band.
• CheckingIt slows down to check an area (a pool, a corner) before continuing.
• Low signalThe scent weakens; the dog persists a little on its heading before casting.
• CastingIt returns to the last good point and sweeps in concentric circles around it, avoiding obstacles, until it finds the trail again.
• Scent lostCasting did not work; the search widens or restarts from the starting point.
• ReacquisitionIt found the trail again and chooses the direction of travel from the freshness of the direct scent, not from old memory.
• Approaching the sourceVery strong, rising signal: it is closing on the person (or on a pool that is not the person, which it will mark and leave).
• Person foundThe dog reached the missing person; playback stops and, in an exercise, the replay opens.

Three behaviour rules hold in every scenario: at the start the dog makes a 360 and sets off in the right direction; wherever it loses the trail, it returns to the last good point and takes the direction of the fresh scent; and when it gets physically wedged (for example in a building corner where rain has pooled a false-strong scent), a safety net walks it out towards open space and, after repeated jams, restarts the search from the starting point. The dog cannot remain motionless.

11Exercises, replay and analysis

An exercise hides the information you would not have in the field. From Exercise ▾ choose Exercise (you work only with the dog's local information, in its perspective) or Blind exercise (no local information): the route, the person and the scent are hidden completely. When the dog finds the person, or when you choose End the exercise and show the replay, the application opens the replay and the Analysis tab.

The replay

View replay plays back what was recorded: the positions of the dog and the handler, the states, the scent field at each moment. The replay's time cursor is independent of the simulation; leave the replay with the same button.

The Analysis tab

Exercise analysis

Compute the analysis after running the simulation with the dog: the length of the person's and the dog's tracks, the search duration, whether the person was found, the mean and maximum distance to the physical route, the zones of rising signal and of signal loss, the reacquisitions, the junctions checked, Time per state and Local wind at key moments. The analysis is descriptive: it does not score the dog.

Junction analysis

Detect automatically the points where the dog's track parts from the person's, or Mark manually on the map; Show the junctions on the map overlays them on the replay.

Instructor notes

Add an observation (text, type, moment) or Place on the map. Notes are saved with the scenario and exported with it.

Compare

Conditions B: the same scenario and seed run in parallel, in split screen, with wind of 2, 15 or 40 km/h, with the direction rotated by 90° or with another weather preset (Compare conditions, Stop the comparison). Compare moments puts two moments of the recording side by side (hh:mm:ss).

Save moment

Saved moments (from the timeline or from here, with a name) can be Restored or compared.

12Presentation mode and full screen

Presentation mode is meant for workshops and projectors: large labels, an interface reduced to the essentials and the option to work in Split screen instructor / dog. The Enhanced visualisation simulation profile in the Scent tab raises the contrast for bright rooms. Full screen hides the rest of the page; Esc returns.

13Saving, export and JSON import

The simulator has no accounts and sends no scenarios to a server. Save scenario keeps it in your browser's local storage (it disappears if you clear the site data or use another browser). Export JSON downloads the file scenario-name.sarsim.json, which you can send to colleagues or archive; Import JSON loads it back, again in the browser, with a check of the format version.

The file contains: the world and its objects, the person's route with modes and stops, the base weather and the initial state (wetness, snow), the timeline events, the dog profile and parameters, the team position, the trail age, quality, simulation profile, saved moments, notes, the seed and the engine version. With the same seed the same scenario runs identically: turbulence, gusts and the dog's decisions are reproducible.

14Keyboard shortcuts and gestures

Shortcuts work when the map has focus (click on it once).

15Frequently asked questions

Why doesn't the dog walk exactly on the person's route?

Because it works with the available scent, not with the route. A crosswind shifts the scent band, buildings deflect and channel it, the sun lifts it, shade keeps it low. A dog working 3–5 m to the side of the route, on the scent band, is working correctly.

Why is there scent where the person never walked?

Airborne scent is transported; at an intersection it can “enter” the side street, and when the wind shifts, bands from different directions overlap. The scent probe and the cross-section show exactly how far the peak has moved from the route.

How do I see what the dog perceives?

Switch to The dog's perspective or Split screen and watch the chart in the Dog tab. For an honest test, start a Blind exercise.

The simulation runs slowly.

In the Scent tab choose Simulation quality: Low, switch off the layers you do not need and use the Heat map visualisation instead of Particles. On a laptop, full screen helps too.

How do I reproduce a simulation exactly?

The same scenario with the same Simulation seed runs identically. Export the JSON: the seed is saved in it.

Where is the in-app help?

The ? Help button in the top bar opens a window with short explanations by topic, the text “About the accuracy of the simulation” and the engine version. The link to this guide is the first line of that window.

What comes next?

The architecture is prepared for importing the GPS tracks (GPX) of the person, the dog and the handler, for historical weather and for real maps, so that a real training session can be replayed over the simulated scent. The buttons in the “Import GPS track” section are visible but marked as a feature prepared for a future version.