# Indoor Altitude Estimate Divergence

Source: https://forum.modalai.com/topic/3970/indoor-altitude-estimate-divergence
Category: Development Drones (https://forum.modalai.com/category/44/development-drones)
Tags: starling
Posted: 2024-11-22 19:23:53 UTC by griffin
Replies: 1 · Views: 435

## griffin · 2024-11-22 19:23:53 UTC

Hey All,

Testing indoors I've had several instances of altitude estimate divergence requiring reversion to manual control and an emergency landing on a starling 2 max.

![altitude_plot_divergence.png](https://forum.modalai.com/assets/uploads/files/1732303157877-altitude_plot_divergence.png) 
![throttle_plot_divergence.png](https://forum.modalai.com/assets/uploads/files/1732303214672-throttle_plot_divergence.png) 

It seems that the error begins when I activate the offboard mode with the default figure 8 loaded.
My assumption is that as the drone yaws it loses some of the VIO points and is uncertain about its altitude causing a rapid climb in offboard and position modes.

What would the best way be to correct this issue? 
- I could try to add visual markers (i.e. april tags) to the warehouse walls to provide more references?
- Does the starling 2 max use both forward and downward facing cameras for VIO? I thought I saw a post about this feature being enabled in the nightly builds but am unsure.
- Should I expect these issues to improve inherently by moving into a more visually active space (inside an unoccupied office area)? I am hesitant to fly in more confined areas without being confident in the aircraft estimate and position holding reliability.

Kind regards,
Griffin

## Reply by griffin · 2024-12-04 23:48:37 UTC

@admin @Moderator Any suggestions on how to prevent this altitude divergence? This happens somewhat regularly and requires reversion to manual control.