- Invalid filtering rules.
- Normally, the start and end time of trajectory and the start and end time of each laser file are prompted by the log. If the time range of the laser file is not within the time range of the trajectory, the size of the result file will be 1KB. please confirm whether the Date of Data shown in the software interface is correct. In the example below, the time period of the trajectory is 175344.001-184407.005, while the beginning and ending time of laser file are -1, which means the time period of the laser scanner file is not in the time period of the trajectory file. Therefore the result is 1KB.
A: When there is abnormal information in the log, the software log window will display “WARNING” in red. This indicates the software has encountered an exception to the data but this generally does not affect the georeferencing results. This is shown in the figure below:
As seen above and below, the software log window is displaying an error in red. This indicates that the some problems are found in the georeferencing process. Under this circumstance, there will be either no point cloud output, or unqualified result. Users need to find and correct the errors before they can get a satisfying result.
A: The severe distortion of the result is usually caused by an error in the Laser Rotation Matrix setting, and it needs to be rearranged according to the installation of different components of the device. The following screenshot shows point cloud data which is distorted because of the wrong laser rotation matrix.
A: This is usually caused by an incorrect leap seconds setting. The time of the point cloud in the software will be transformed to UTC time. Please confirm that the POS time is UTC time or GPS time. If the POS time is UTC time, the leap seconds should be set to 0, otherwise it should be set to -18. Note that some RIEGL instruments have the synchronize-offset. This synchronize-offset value is provided by the instrument supplier. Users need to add this synchronization-offset to the leap seconds.
A: The filtering condition is used to remove the noise. But if users set the parameters in filter improbably, the power line may be partially removed as noise. To solve the problem of missing power line in the result, suitable filtering conditions should be set to filter the data. Or it may be caused by the maloperation to the aircraft during the data collection and the quality of the point cloud is not good.
A: When flying closely to the transmission tower, the maloperation to aircraft may result in the inaccurate POS result. And that will lead to the misalignment of the power line in the result.
A: The timestamps of the point cloud is corresponding to the time records in POS files.
- Check whether the Camera Installation is checked in the software.
- Check the Camera File and the Images. The images should be put in the Image folder.
- Check if the timesteps of images match with the GPS time, if the Split by GPS Time function is used.
A: If the color rendering result is incorrect, this is usually due to the incorrect Camera Rotation Matrix. If the color information of the point cloud translates along the flight direction, it may be caused by mismatching of image data and Cam information.
A: No. LiGeoreference set the software language according to your computer OS language. If the OS language is Chinese, LiGeoreference will be in Chinese version. Otherwise, it will be in English version.
A: There may not be enough space in the output path disk. This will cause errors in writing LiData data. Please make sure that there is enough storage space.
A: To solve this problem, you may need to:
- Check if the timestamps in your POS is proper in LiGeoreference. In LiGeoreference, timestamps are in UTC second of week. Therefore, the timestamps in POS file should be in UTC second of week as well.
- Check if the data in PCAP file is synchronized. For detailed information, please referred to Velodyne LiDAR VLP-16 User Manual. The information of GPS data synchronization with laser scanner is in the chapter 7.4. The information of the timestamps format of PCAP file is in chapter 22.214.171.124. The information of data synchronization is in chapter 9.3.3. The information of point timing calculation is in the chapter 9.4.