# Route planning

> Source: https://topodrone.com/knowledge/topodrone-slam-100/route-planning/
> Section: TOPODRONE SLAM 100
> Updated: 2026-10-02

TOPODRONE SLAM 100 is a handheld laser scanner for data collection and does not support automatic route planning. Plan your survey routes properly before starting. Planning the route in advance effectively ensures the overall accuracy of the data.  
1.    Closed-loop route  
To reduce the accumulated error during data collection, carefully plan closed loops, i.e. collect data of the same area at different times. The key point of a closed loop is overlapping areas about 5 ~ 10 m long. The overlapping areas can be traversed in the same direction or in the opposite direction.

| Start and end of survey | Start and end of survey | Start and end of survey |
| --- | --- | --- |
| ![Route planning](https://topodrone.com/knowledge/i/bf9a3a410e78071e.png) | ![Route planning](https://topodrone.com/knowledge/i/590e1a58d69f9d1e.png) | ![Route planning](https://topodrone.com/knowledge/i/47c57f4fd060fd54.png) |
| Incorrect closure of the survey start and end | Correct closure of the survey start and end |

Fig. 3.1.1 Different options for planning a closed loop.

2. Closed loops in single-story buildings

The error accumulates as the distance increases. In a single-story building there should be as many O-shaped closed loops as possible instead of linear loops, which minimizes the error.

Why are several small O-shaped closed loops better for global accuracy? Fig. 3.2.1 shows three route layouts in the same area. Measure the shortest distance between two points and estimate the corresponding error, assuming that every 100 m of distance gives a relative error of 1 cm.

|   | **Distance A-C** | **Relative error A-C** | **Distance B-C** | **Relative error B-C** |
| --- | --- | --- | --- | --- |
| **L-shaped route** | 500 meters | 5 cm | 250 meters | 2.5 cm |
| **Single O-shaped route** | 120 meters | 1.2 cm | 250 meters | 2.5 cm |
| **Route with several O-shaped loops** | 120 meters | 1.2 cm | 75 meters | 0.75 cm |

| ![Route planning](https://topodrone.com/knowledge/i/f3c0770057c30076.png) | ![Route planning](https://topodrone.com/knowledge/i/c1b9349facc99f72.png) | ![Route planning](https://topodrone.com/knowledge/i/92a3b6df27b5794e.png) |
| --- | --- | --- |
| L-shaped out-and-back route | Single O-shaped closed loop | Closed loop with several O-shaped loops |
| (Less effective) | (More effective) | (Most effective) |

Fig. 3.2.1 Route planning in a single-story building.

3. Closed loops in multi-story buildings  
When surveying multi-story buildings, plan the route so that there are as many closed loops as possible not only on each floor but also between floors. The best route starts and ends at the stairs on both sides.