# m500 estimated flying paths

Source: https://forum.modalai.com/topic/719/m500-estimated-flying-paths
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2022-02-08 02:11:31 UTC by yu zhang
Replies: 4 · Views: 939

## yu zhang · 2022-02-08 02:11:31 UTC

Hi team,

I output this figure by px4 flight review: 
![Screen Shot 2022-02-08 at 11.51.19 AM.png](https://forum.modalai.com/assets/uploads/files/1644285626205-screen-shot-2022-02-08-at-11.51.19-am.png) 
I am enabling outdoor flight mode by GPS settings.

1. I am wondering how the estimated path (red line) is generated? Is it generated using VIO or GPS only or VIO + GPS? Where could I locate the source code for this path estimation? 

2. I am also wondering what does the "Setpoint" in the right corner legend represent for?

3. For the GPS showing in the figure:
![Screen Shot 2022-02-08 at 1.07.31 PM.png](https://forum.modalai.com/assets/uploads/files/1644286090234-screen-shot-2022-02-08-at-1.07.31-pm.png) 

Is it possible to improve both H and V position accuracy by GPS settings on m500? Could I modify the num satellites used? What does the GPS Fix stand for?

Thanks.

## Reply by Eric Katzfey (ModalAI staff) · 2022-02-08 16:43:58 UTC

@yu-zhang These are all questions that would be better answered by the PX4 community. Also, all of the PX4 software is open source so you could probably look through it and find the answers that way.

## Reply by yu zhang · 2022-02-08 23:26:26 UTC (in reply to Eric Katzfey)

@Eric-Katzfey I thought the estimated path was generated by voxl VIO. All right, I will have a look at px4 community and check if this is a default path estimation by px4.

## Reply by Eric Katzfey (ModalAI staff) · 2022-02-09 00:12:18 UTC (in reply to yu zhang)

@yu-zhang Sorry, didn't see the VIO part. VIO will send an odometry mavlink message to PX4. Code for that is here: https://gitlab.com/voxl-public/modal-pipe-architecture/voxl-vision-px4/-/blob/master/src/vio_manager.c

## Reply by yu zhang · 2022-02-09 06:36:18 UTC (in reply to Eric Katzfey)

@Eric-Katzfey Thanks, I am looking for this one ;)