Are you referring to the obstacle avoidance system when mentioning VPS-cameras? The obstacle avoidance is not operational during an autonomous flight, meaning when flying a grid, double grid, or circular mission with Pix4Dcapture. It is recommended to make sure the flight plan is defined in a clear area and high enough to avoid obstacles.
On the other hand, obstacle avoidance should be enabled during the free flight missions.
As for the vertical surface, you will have to use the Free Flight mission. Images are captured given a space interval (vertical / horizontal distance), meaning the user does not need to trigger the camera shutter but has to manually control the drone. Flying with the app is not required to successfully process projects, but it aims at assisting our users to optimize their flight plans. This is the only option for now.