Watch the reveal, then try the lesson yourself. What can B confirm from position messages alone?
Illustrated walkthrough with a synthetic US English female voice. English on-screen text and optional captions support silent viewing. Generated from the Learning Lab model; not a screen recording.
00:00–00:12 · Observe. Both worlds send identical position messages. Can B tell which world reports an incorrect position?
00:12–00:24 · Reveal. World 1 reports its true position. World 2 reports a position 8 metres ahead of its truth. The gold ring is a claim, not another vehicle.
00:24–00:36 · Compare. Both move 3 metres each second; a constant translation cancels in position differences. Equal movement does not establish correct absolute position.
00:36–00:48 · Create. Open Learning Lab, change offset and speed, write a question, export lesson JSON and reopen it to share the exercise.
Spoken narration
Two worlds. Identical messages. Can receiver B tell which world reports the wrong position? Look only at the information B receives.
Now reveal the true positions. In world two, the claim is eight meters ahead of the car. Yet B receives the same messages.
Both cars move three meters each second. Matching position changes do not prove that the reported position is correct. B needs independent evidence.
Try V two X Observation Lab. Create a lesson, reveal the evidence, and share the scenario. Synthetic examples, not a detector or safety verdict.
One message per simulated second, immediate delivery, fixed +8 m offset in world 2. Animation time is slowed for explanation; the movement is interpolated between model samples. Receiver readouts update only at those samples. The final five-second model state is held. No real radio traffic, detector bypass or safety outcome is demonstrated.
Explore → compare → reproduce
Two cars, three position marks: A sends messages; B reads them. A′ marks where A says it is. The purple “B remembers” pin marks the position in B’s latest received message. A′ and the pin are not extra cars.
Numbers and formulas (optional)
Delta means change between two transmissions here. Δp is the true position change; Δp′ is the reported change. (3, 0) m means +3 metres along X and no change along Y, not the car’s current coordinates. demo-21 is just a message ID. R is the technical name for the “B remembers” pin.
Shared orientation and zoom · framing uses each perspective’s data
A · synthetic ground truthA′ · reported positionPurple pin · B remembersB · receiver
How to read the scene and its limits
Mint: true position A · Gold: reported position A′ · Blue: receiver B. Rings and labels mark coordinates, not radio range. Camera motion is smoothed; received positions still step with each message.
Dots mark position samples; dashed links show their order, not a verified route. The receiver pane draws only arrived claims, with no interpolation through missing observations. Ground truth appears there only when its teaching overlay is enabled.
Each pane fits its own data: scales may differ. Compare coordinates, not screen distances. Overlapping vehicles are not a simulated collision.
A: sender · B: reader · Purple pin: the position B remembers. Story 2 also shows A′: the current claim.
Detailed comparison · three panes
True position
Vehicle A · synthetic reference
Reported position
A′ · position-claim marker, not another vehicle
Receiver observation
Holds the last received position
Offset boundaries
Markers show sender-side changes; the receiver sees contents only after arrival. A change between transmissions appears in differences only at a later sent message.
Build your own scenario · advanced settings
01 / Configure a scenario
Explore further: how do messages travel from A to B?
V2V within V2X · A sends → B receives
Two vehicles, one direction: A sends position claim A′; B holds the latest arrival. A′ is position content, not a third vehicle. Application-level illustration, without radio, ACKs or CAM/BSM encoding.
A · Sender vehicle
→
Message schedule
→
B · Receiver vehicle
Simulation-wide teaching view: configured omissions are not knowledge available to B. Arrows show data direction, not a radio path or coverage range.
Send / omit / receive log (up to current time)
At (s)
ID
Event
For deeper inspection: numbers and message history
03 / Geometry checks
Sender comparison — ground truth available
Receiver — only two arrived messages
Interpretation limits
Equal differences do not prove position correctness. The receiver lacks ground truth to compute Δp; checking position correctness requires an independent reference.
These are formula checks on known synthetic data. They are not a detector, safety assessment, or benchmark result.
Recent messages
ID
Sent (s)
Received (s)
State
Take the test with you
Download the scenario to import again; keep the report as your expected-result reference. After import, seek to the time recorded in the instructions. This tests observation limits, not a detector.
Save the applied scenario, current time, synthetic trace and geometric differences. Reports contain no camera settings, account information or attack-detection results.
Formulas, assumptions and limitations
A(t) = (−30 + 3t, 0) m; B(t) = (0, −20 + 2t) m. p′(t) = p(t) + c when start ≤ t < end; c = (dx, dy).
One message per second; fixed delay and user-selected periodic omissions. No RF, GNSS, certificates, vehicle dimensions, collisions or driver response are simulated. Crossing point trajectories do not establish a crash. A constant offset cancels in differences only within a segment with that same offset. Values and vehicle labels are authored from formulas, not measured traces.
Applying a configuration resets time. Exports use the applied configuration, not pending edits. Imported files are read in your browser and are not uploaded.