> 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. 

<figure><img src="/files/zyTitrX2q4T5nPfh6bsI" alt=""><figcaption></figcaption></figure>

1. Once the scanner has been turned on, calibrated, and mounted, proceed with these steps.
2. Make yourself a new dataset.&#x20;

{% hint style="info" %}
I**f you close the dataset you will not be able to add to it again.**&#x20;

However, you can combine two datasets after extracting them from the scanner during processing stages.&#x20;
{% endhint %}

### Scanning Interface

Begin the scan only after you have understood the interface and spatial requirements of the VLX.&#x20;

* New dataset > name your dataset > start mapping
* This screen will now show up (LIDAR mapping of your environment)

<figure><img src="/files/ZG5wTcz9Y1gH0FUq1rFA" alt=""><figcaption></figcaption></figure>

Use the pause/start button when

* people or moving objects are entering the environment to minimise noise and alignment issues.&#x20;
* 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

<figure><img src="/files/zJlTdlfhfm9si81ET1xQ" alt=""><figcaption></figcaption></figure>

* 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.

<figure><img src="/files/w05pMNFH95F93LdtocPN" alt="" width="563"><figcaption><p>Locating the manual photo button</p></figcaption></figure>

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. &#x20;

* These options can be selected in settings OR if you have already started scanning, but tapping the button displayed below

<figure><img src="/files/muDD98vP81n1HYXlPPHo" alt=""><figcaption></figcaption></figure>

* You can review photos in the photo viewer. Here you can also delete photos containing unwanted elements to exclude them from the colour information.&#x20;

<figure><img src="/files/op3CDPcrKgklsrowIvEI" alt=""><figcaption></figcaption></figure>

{% 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.&#x20;

**Drift**

SLAM is therefore an incremental process, which means that small mis-alignments will accumulate over large distances; this is called **drift.** &#x20;

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.&#x20;
* Alternatively, you can scan the problem area again in a different dataset.&#x20;
* Both options reuquire post-processing.&#x20;
* Allowing **loop closures** while scanning will reduce the possibility of drift.

## Loop Closures

Points where you overlap point-cloud data are called loop closures.&#x20;

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.&#x20;

{% 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.

<figure><img src="/files/Gxf0ASm0RIKwo8oARypx" alt="" width="563"><figcaption></figcaption></figure>

<figure><img src="/files/hS1nSCSIjFe0KDWyWAkv" alt="" width="563"><figcaption></figcaption></figure>

<figure><img src="/files/0hUZiBiSJ7o12UIpKvix" alt="" width="563"><figcaption></figcaption></figure>

{% 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. &#x20;

**Do not scan in high temperatures.** The scanner can overheat if it exceeds 35 degrees Celsius. &#x20;
{% endhint %}

**Lighting conditions**

Overcast light produces the best colour info from the photos, however bright light and dark light are suitable to scan in.&#x20;

* Please note than in bright light, reflective surfaces may not scan properly.&#x20;
* 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.&#x20;

**Obstacles**&#x20;

More info on how to navigate obstacles and environmental factors while scanning is provided on the next page