# Attempt to improve odometry using Opticalflow(&rangefinder)

Source: https://forum.modalai.com/topic/3521/attempt-to-improve-odometry-using-opticalflow-rangefinder
Category: VOXL 2 and VOXL 2 Mini (https://forum.modalai.com/category/26/voxl-2-and-voxl-2-mini)
Tags: voxl-2
Posted: 2024-06-04 10:59:49 UTC by Jetson Nano
Replies: 1 · Views: 428

## Jetson Nano · 2024-06-04 10:59:49 UTC

Hey @Eric-Katzfey, @James-Strawson  @Tom-Kaufmann, 

I've been using Starling for quite a while. Congratulations on a great product.
One of the things I noticed was that when using voxl-mapper for a significant time (like 15mins), the accumulated drift becomes a serious issue. I want to try and reduce the accumulated drift.

An option to solve this issue is to use an OpticalFlow/Rangefinder with an external FC. I have completed this setup successfully. I can use my MAV in position mode with the fused odometry without issues. VOA works as well.

I know from the docs and GitLab that voxl-mapper takes 2 inputs whub_body_wrt_fixed and tof. Is there a way to pass the fused odometry instead of whub_body_wrt_fixed? [ I want the mapper to use this data instead of whub_body_wrt_fixed]. The message type of the fused odometry is nav_msgs/Odometry.

1. Will I need to modify the voxl-mavlink-server to achieve this?
2. How do I get the mapper to use the fused odometry data?
3. How do I synchronize these new position estimates and the pointcloud?

I'm currently working on this project. So any suggestions or ideas will be instantly implemented, tested and reported back. i hope to hear from you.

Thank you

## Reply by Jetson Nano · 2024-06-13 10:08:01 UTC

@Chad-Sweet, @James-Strawson, @tom any updates?