# Vertical Only Adjustment

If GCPs are present in a project, they will, by default, be enabled for use in LiDARSnap:

<figure><img src="/files/uCxPXDhUTVoM96BpeFBH" alt=""><figcaption></figcaption></figure>

When performing trajectory optimization with GCPs enabled, LiDARSnap will consider the vertical position of control points when determining trajectory adjustments.&#x20;

{% hint style="info" %}
GCPs marked as **check points** are not used by LiDARSnap.
{% endhint %}

{% hint style="warning" %}
It's generally not advisable to enable GCPs when running LiDARSnap on aerial data sets, as the influence of the GCP on LiDARSnap and the adjustment made to match the GCP is not easily reportable. Only enable GCPs with LiDARSnap when data sets are particularly difficult to optimize, such as data sets where the processed trajectory quality is low.&#x20;
{% endhint %}


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