XGRIDSDocs

Precautions

This chapter summarizes the key points to note during scan startup, scanning, control point mode, RTK mode, colorization mode, and accuracy verification.

Scan Startup Stage (Instrument Initialization)

  1. Avoid shaking; it is recommended to place the device on flat ground for static startup. When the device starts, keep it as steady and shake-free as possible (support it if possible), and make sure no person or obstruction is in front of the LiDAR. After startup, wait at least 10s after the point cloud appears on the phone screen [if you are using the latest LixelGO V1.1.0, pick up the device only after LixelGO indicates initialization succeeded], then pick up the device to capture. Pick it up slowly and avoid abrupt movements.
  2. During initialization, the operator should avoid blocking the LiDAR and stay somewhat farther from the device. Aim the LiDAR at an area with more features, avoiding feature-poor environments such as open plains, environments with refraction such as large glass surfaces, and areas with many moving objects, so as to ensure sufficient initialization features and better data results.

General Precautions

  1. Avoid large, fast body rotations or sudden stops, which cause the device to also rotate and swing fast and widely, affecting the accuracy and quality of the point cloud mapping to some extent.
  2. When scanning, a normal walking speed is recommended. For situations with few features, narrow spaces, or turns, slow down.
  3. When scanning, tilt the device slightly forward by about 15° for a more complete field of view. When walking normally, the device tilt must not exceed 20°. In some narrow areas where you need to scan the full ground or a ground target, the tilt may briefly exceed 20° but must not exceed 30°.
  4. Avoid large-scale object obstruction within 1 m of the LiDAR's field of view for extended periods where the obstruction exceeds 50% of the LiDAR's field of view.
  5. To ensure scan quality and accuracy, keep at least 0.5 m from the scanned object when scanning.
  6. To ensure the scan data results, when scanning some important ground data, scan at a closer distance where possible, and keep the correct posture: hold the scanner in the center of your body and avoid getting too close to the ground.
  7. Outdoor scenes such as roads and streets have many moving objects like pedestrians and vehicles; avoid aiming the LiDAR at moving objects when scanning. When conditions allow, if there are many moving objects on one side, aim the LiDAR at the other side to avoid too many moving-object features in the LiDAR's field of view.
  8. For indoor scenes involving multiple rooms or floors, open the indoor doors in advance. When passing through a door, scan slowly and pause sideways at the doorway for a while so that features on both sides of the doorway can be scanned at the same time. If a door is not open during scanning, turn slowly before approaching it, keep the instrument facing away from the doorway, open the door with your back, and enter slowly.

Control Point Mode

  1. When setting the instrument down to mark a point, avoid heavy impacts with the ground that cause vibration; when picking the instrument back up after marking a control point, pick it up slowly and steadily, otherwise abrupt movements will affect accuracy.
  2. Mark the control point first. After LixelGO confirms the control point was added successfully, pick up the device and circle around the control point 1–2 times or pause for a while to obtain a more complete point cloud around the control point.
  3. After marking a control point, if you want to end the project recording, wait at least 15s before ending it.
  4. To ensure post-processing accuracy, the control point spacing must keep the distance between two points < 50 m, and the points must be evenly distributed within the survey area. Note: control points must not lie on the same line.

RTK Mode

  1. The RTK module can only be used when RTK signal is available; it cannot be used indoors where there is no signal.
  2. Pay attention to how you hold the device. For the new tilt RTK bracket, under normal conditions keep the device tilt within 20° so the RTK antenna is vertical; the RTK antenna tilt must not exceed 10° at most.
  3. Minimum requirement [absolute coordinate conversion is possible, but accuracy will be reduced]: to ensure the post-processing point cloud coordinates can be converted, pay attention to the scan spatial range and ensure a certain open area within the region. The scan area must be above 10 m and there must be at least > 20 valid RTK data points [valid data: valid points > 20 as shown in LixelStudio].
  4. For accuracy verification, the capture route must be over 100 m and not a straight line.
  5. To ensure post-processing point cloud accuracy, keep any continuous non-fixed RTK section < 50 m where possible.

Colorization Mode

  1. To ensure colorization results, the data capture must last more than 2 minutes, and you must move during capture; do not keep the scanner still in one position.
  2. Point cloud colorization depends on the surrounding environment and ambient light. For dark environments, if colorization is needed, turn on lights to ensure even brightness around. Also avoid overexposure and excessive light during scanning.
  3. Pay attention to how you hold the scanner during capture. Avoid blocking the panoramic camera or the onboard camera, or having objects on one or both sides of the camera for a long time, so as not to affect colorization.

Accuracy Verification

For accuracy verification, at points where targets are attached, scan around the target or pause appropriately at the target to obtain a more complete target point cloud, which improves the success rate of automatic target point extraction during subsequent accuracy verification.