10 meters is the lowest altitude that Pix4Dcapture supports for all automated missions, including single grid, double grid, circular, and polygon.
You can fly a Freeflight mission lower than 10 meters above ground level with Pix4Dcapture, however, I do not recommend that you fly a Free Flight mission to capture your project area. You can learn more about planning and flying a Free Flight mission at: How to prepare and start a free flight mission.
I have taken the opportunity to share your interest in flying an automated mission below 10 meters for consideration as part of the ongoing development of Pix4Dcapture.
Please keep in mind that your drone will fly at the same height above its home point, so you must take extra caution when flying an automated mission at a low altitude, especially when the terrain elevation varies. Your drone will not automatically follow the terrain and I recommend that you do not rely on your drone’s collision avoidance system to account for changes in terrain elevation.
If you have not already done so, please consider checking if you will be able to identify your project’s smallest features of interest with the ground sampling distance you will achieve when your drone flies at approximately 10 meters above ground level. You can estimate your project’s ground sampling distance with Pix4D’s Basic GSD Calculator and find all of the camera parameters you need for the calculation in the Bundle Block Adjustment Details section of your recent Pix4D Quality Reports. You may find that you are able to gain all the insight you need when flying at 10 meters above ground level, or even higher.