# SLAM

While most SLAM data is captured indoors, without GNSS reception, it is important to begin your data acquisition outside to allow the system to receive at least GPS time and preferably record an initial position to globally reference your indoor scan. Note that georeferencing will be more robust if your scan has several periods of GNSS reception at different places intermixed with periods of indoor scanning.

To get started with SLAM, mount the antenna as shown. You can use the plate that was attached to the unit in the package as a handle. Power on the rover outside. Connect via the [web interface](https://docs.phoenixlidar.com/lidarmill-rover/connect-to-rover/connect-via-web-interface) and click "Start Rover". Once you see the system tracking satellites in the NAV tab (19 satellites in the following screenshot), activate the LiDAR sensor in the SENSORS tab:

![](/files/-M_cXzNUpZEwtKkOwWcu)

Keep the unit steady and with a good view of surroundings for the first 10 seconds once you see LIDAR data come in. This is to build a good initial map for SLAM to orient itself in. Then perform a smooth sweeping motion while scanning, as shown here:

![Sweeping motion to capture surrounding surfaces](/files/-M_cePmtEIZvLphl2vRl)

Continue performing a smooth sweeping motion while you collect LiDAR data. As you continue your scan indoors, be aware that LiDAR pulses may reflect off of glass windows and doors, resulting in an undesirable georeferencing of the resultant point. 

![Scanning indoors with SLAM](/files/-M_chg2Zk8cEGFKmvtqM)

{% hint style="info" %}
Be aware of the limitations of the LiDAR sensor itself. For instance, small rooms may require extra scanning, as many of the LiDAR pulses will not register as a return due to the minimum range of the scanner; with the Velodyne VLP-16, this minimum range is 1 meter. As well, ceilings and floors will require more deliberate scanning than features at eye-level, as the field of view on the LiDAR scanner is narrow and will not typically receive many of these points. 
{% endhint %}

* Click [here](https://docs.phoenixlidar.com/lidarmill-desktop/post-processing/slam-workflow-beta#performing-acquisition) for more information on SLAM Acquisition


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