# Automatic Block Division
For a one-time import of hundreds of thousands of images for aerial triangulation calculation, Get3D Mapper supports automatic division of blocks through algorithms, and the whole process is convenient and efficient without manual effort.
In Aerial Triangulation Setting Interface, select **Auto Split** and set the **block image number**.
Split Setting
The software will quickly and automatically divide the sub-blocks by algorithm.
Dividing sub-blocks helps to improve computing efficiency, increase cluster utilization, and facilitate parallel computing in the cluster.
**Version Before 6.2**
The automatic block division in version 6.2 operates as follows:
For an imported block, select it, right-click it, and click **Split Sub Block**. the Split Photo Group window will pop up.
Select the block, click **Auto Split**, and enter the number of photos you want to include in a single sub-block. Click **Start Split** in the upper right corner.
Split Photo Groups Interface
Auto Split Interface
The software will quickly and automatically divide the sub-blocks by algorithm.
Click **OK** in the lower right corner to finish splitting the sub-blocks.
When a single block contains many images, clicking Submit AT brings up a pop-up that suggests dividing sub-blocks.
