My map and anchor residuals are worse when I use control points

  • Updated on Feb 4, 2025
  • Published on Jan 3, 2024
  • 1 minute(s) read

Issue description

It seems like when I use control points they make the quality of the scan worse and not better.  

Troubleshooting procedure

  1. There could be an issue with the surveyed control points file. To determine if it is this issue, contact the person who surveyed the points.

  2. An issue with the sensor frame (IMMS calibration file), in particular with the belt hook sizes. To determine if it is this issue issue check the following:
    Open the sensor_frame.xml  file from the Dataset with the issue and compare it to a sensor_frame.xml file of another device (which is known to function well). On an example below the device with the perceived issue is on the  left and good one is on the right.

  • If you look at the L size of the belt hook, you can see that the z value is ~10cm off from the other VLX.

  • Also comparing the L size to other sizes (M, S, XS) we see that the values are not in an equal sequence with around 3cm space between the (along z axis).

  • This is a good indicator that something is wrong with the calibration file, if this is the case contact support@navvis.com and a new file can be generated.

  1. An issue when capturing control points.

Check the control points location on the panorama images and compare them to the marker on the quality map. For example, points 68 and 69 are placed on the container (we call wall-mounted points). The black cross that marks their location on the quality map (picture below) should therefore be directly on the white line representing the surface of the container. However, this is not the case and it indicates that the Add button was pressed too soon or too late.

For comparison, a wall-mounted control point should look like this, directly on the wall:

You will know if you have captured a wall-mounted control point correctly during the scanning if the circular yellow marker looks perpendicular to the viewing perspective. Compare how it looks for a control point on the floor and the one on the wall (named "wall1"):

Reference

Review how to correctly capture a control point, refer to the control points.

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