> For the complete documentation index, see [llms.txt](https://ms-kb.msd.unimelb.edu.au/next-lab/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ms-kb.msd.unimelb.edu.au/next-lab/3d-scanning/guides/vlx/preparing-to-scan.md). # Preparing to Scan ## Interface ### Datasets This section provides an overview of datasets. Familiarise yourself before beginning your scan.

1. Once the scanner has been turned on, calibrated, and mounted, proceed with these steps. 2. Make yourself a new dataset. {% hint style="info" %} I**f you close the dataset you will not be able to add to it again.** However, you can combine two datasets after extracting them from the scanner during processing stages. {% endhint %} ### Scanning Interface Begin the scan only after you have understood the interface and spatial requirements of the VLX. * New dataset > name your dataset > start mapping * This screen will now show up (LIDAR mapping of your environment)

Use the pause/start button when * people or moving objects are entering the environment to minimise noise and alignment issues. * the device is being where you do not want to scan or take photos, but still want to continue capturing in the same Dataset {% hint style="info" %} **Note:** In pause mode, only the 3D scan process is paused. Localization is always running. To avoid impairing the quality of the recorded map, **do not** move faster or less carefully than normal. {% endhint %} {% hint style="warning" %} **Caution:** If the speed indicator turns red, it means that the user is moving so fast that the quality of the dataset might suffer. Move or rotate more slowly. {% endhint %} ### Photo Settings

* Point cloud colour is achieved by projecting a photo onto the point data. * There are two methods for taking photos; 1. **Manual:** Trigger the photo manually using the button below the screen / above the handle.

2. **Automatic:** Once you travel the specified distance, the scanner will automatically take photos (adjustable in settings). You can take additional photos manually while automatic mode is switched on. * These options can be selected in settings OR if you have already started scanning, but tapping the button displayed below

* You can review photos in the photo viewer. Here you can also delete photos containing unwanted elements to exclude them from the colour information.

{% hint style="info" %} It is recommended to take photos every 1m for good point-cloud colouring. In more open spaces a photo every three meters is sufficient. {% endhint %} *** ## Plan Your Scan #### SLAM The VLX 3 uses LiDAR-based SLAM (Simultaneous Localisation and Mapping) technology. SLAM is able to map out, **and** place the device spatially within the environment while moving. As you walk, it will continuously capture data and align it, building up a digital environment. **Drift** SLAM is therefore an incremental process, which means that small mis-alignments will accumulate over large distances; this is called **drift.** On the dashboard, this may looked like curved forms where it it is actually linear, or overlapping, misaligned point clouds. * If this occurs, return to a point of the scan that has been scanned with higher accuracy, and make your way towards to the problem area. * Alternatively, you can scan the problem area again in a different dataset. * Both options reuquire post-processing. * Allowing **loop closures** while scanning will reduce the possibility of drift. ## Loop Closures Points where you overlap point-cloud data are called loop closures. While you loop around the site during the scan, come back to points you have already scanned to create points of reference and better align your data. {% hint style="success" %} Your original path is shown as a solid line on the user interface. Cross this line to create a loop closure. {% endhint %} Examples of how you might do this (in plan view) are below.

{% hint style="info" %} Ensure loop closured every 15 - 30m of your scan. This can get complicated so where possible, plan ahead. {% endhint %} *** ## Time Limits Each dataset has a limitation of 1 hour for manageable file-sizes.\ If your project may exceed this time in size, please refer to the section on Large Sites in the next article. **Battery Life:** 1.5hrs for 2 batteries, hot-swappable.\ **Charge Time:** 2hrs.\ \ With the four batteries, you should be able to get up to 3 datasets (1 hour each). ## Preparing the Space To ensure the quality of the scanned data, prepare the site so that you do not encounter any obstacles. Where possible, complete the steps below: * Open all the doors with doorstoppers * Turn on all lights and open window coverings, such as curtains and blinds. * Move obstacles and any confidential material out of view. * Ensure the batteries are fully charged. * Ensure the SSD is inserted correctly into its slot and is ready to receive data. {% hint style="danger" %} **Do not use the scanner in the rain.** If it starts raining during your scan, move to cover immediately. **Do not scan in high temperatures.** The scanner can overheat if it exceeds 35 degrees Celsius. {% endhint %} **Lighting conditions** Overcast light produces the best colour info from the photos, however bright light and dark light are suitable to scan in. * Please note than in bright light, reflective surfaces may not scan properly. * If you are scanning in the dark, photos will bot be able to pick up colour information. Also be wary of your surroundings and do not risk falling. **Obstacles** More info on how to navigate obstacles and environmental factors while scanning is provided on the next page