# Additional recommendations

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

1. Walking speed  
Data is collected at normal or slow walking speed under standard scanning conditions. In small spaces such as karst caves, stairs and tunnels, turn as slowly as possible, and even more slowly when changing scenes, and keep as much free space in front of the sensor as possible.  
2. Avoiding moving objects  
SLAM matching must be done on static scenes, so whenever possible do not face scenes with many moving objects or people. If most of the collected data relates to moving objects, matching based on them will shift the static objects. Avoid such situations as much as possible. If it cannot be avoided, stop until the moving object has gone.  
2.1. Avoid moving crowds  
During data collection, the operator must avoid being surrounded by moving objects.  
2.2. Avoid large moving objects  
When collecting data in quarries, avoid mining dump trucks moving close in front (within 10 m); avoid collecting data near large vehicles such as buses and cars.  
3. Notes on collecting control points  
•    Keep moving throughout data collection. When collecting control point data, place SLAM 100 still on the ground; after the control point is collected there is no need to remain still, otherwise the data will not match.  
•    The number of points recorded in the control point file must strictly match the number of actual points, otherwise the calculation will be wrong.  
•    Check the number of control points and the X/Y/Z coordinate order.  
•    Make sure nothing blocks the laser or the target area while collecting a control point.  
•    It is recommended to place more than 4 ground control points and distribute them as evenly as possible.  
•    It is recommended to collect data for 10 ~ 30 seconds before collecting the first control point.  
•    Keep SLAM100 still while collecting a control point.

4. Frequently asked questions about data processing.

| Problem | Solution |
| --- | --- |
| 1. The point cloud data is a straight line from the start of the calculation. | Skip a few seconds at the beginning and recalculate; if you can collect the data again, stay still for 10 seconds before collecting. |
| 2. The calculation goes normally at first, then the point cloud data becomes a straight line. | Too few features in the survey area lead to a large accumulated error, which shifts the point cloud data. The operator can scan with zigzag passes or split the area into parts and then match the parts together. |

![Additional recommendations](https://topodrone.com/knowledge/i/e7d246bce06cf01b.png)

![Additional recommendations](https://topodrone.com/knowledge/i/c023239dfb72b3c8.png)

| 3. Control points are imported to match the coordinates, but parts of the point cloud turn out to be missing. | Check whether the number of control points entered in the program matches the number actually collected. If they differ, check the collection method and dwell time by reviewing the images. |
| --- | --- |
| 4. The point cloud data is tilted instead of horizontal. | Skip more data and recalculate, or try other software (for example CloudCompare) |
| 5. The point cloud is upside down. | Wrong control point file format or wrong order of the northing and easting coordinates. |
| 6. Processing takes too long. | a. If at the matching stage, the computer may be too weak, too many programs may be running, or there is too little RAM   b. If at the point cloud optimization stage, the computer may be too weak and needs replacing.   c. If at the point cloud colorization stage, the data volume may be too large and must be colorized in parts. |
| 7. The GCP folder has no result file, and the OUTPUT\>temp\>temp folder has no tie point file. Clicking GCP opens the "open control point" window instead of the "control point processing" window. | There is a control point encoding error, so the software cannot read the control point file. Set the control point file encoding to ANSI and recalculate. |