Realism check
Does Dream match real Gurgaon roads?
We counted how often each kind of event happens in our dashcam footage and in Dream. 12 of the 12 kinds we have measured happen about as often in both.
How often each event happens
Each band is how often it happens on real roads. Our sample of footage is small, so it is a range, not a single number; the line inside is our best estimate. The dot is the simulator: inside its band is a match.
Not in the chart: cow standing in the road, dog running across and u-turn across the road. Our labelled clips do not include them yet, so the simulator uses rates we assumed, and says so.
How fast traffic moves
Our dashcam car's speed from its GPS, against the cars driving alongside ours in the simulator.
Typical speed
20 km/hReal roads18 km/hSimulator
Close.
Time spent standing still
14%Real roads34%Simulator
Too much in the simulator. Part of it is the test driver: our car in these runs is a cautious textbook planner, which stood still 30% of the time, and the traffic queues with it. Part is how junctions without signals clear. We are working on both.
What we cannot check yet
How close vehicles get to each other, how hard they brake and how they weave between lanes. These need every vehicle's position in metres, and our footage comes from a single camera, so we cannot measure them precisely yet. More labelled footage will also narrow the bands above.
How we measured
- Real roads: 100 random 4-second clips from our dashcam drives in Delhi NCR, each labelled by a person with the main event in it. When several things happen in one clip, the person picks one by a fixed priority list.
- Simulator: 48 drives on seeded routes in Gurgaon traffic, about 3 hours in all, by a standard textbook planner (the Intelligent Driver Model). Each drive is cut into 4-second windows and counted the same way the clips were labelled.
- The bands are exact 95% intervals for a count of rare events (Poisson). The simulator's event generator aims at the measured rates, so we also ran the traffic with the generator off: then 6 of the 12 kinds still fall inside their bands from the traffic alone.
- Speeds: our car's GPS speed once a second, leaving out minutes in which it never moved faster than walking (mostly parked recordings), against every car going our way within 60 m of ours in the simulator, once a second.
- Anyone can rerun this check:
python -m thirdeye_sim.realism.