# Optical flow usable distance

**URL:** <https://forums.openmv.io/t/optical-flow-usable-distance/7945>\
**Category:** OpenMV Boards\
**Created:** [February 9, 2023, 3:31am UTC](https://forums.openmv.io/t/optical-flow-usable-distance/7945 "2023-02-09T03:31:13Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Lukita](https://avatars.discourse-cdn.com/v4/letter/l/ba9def/32.png) [@Lukita](https://forums.openmv.io/u/Lukita)\
**Post date:** [February 9, 2023, 3:31am UTC](https://forums.openmv.io/t/optical-flow-usable-distance/7945/1 "2023-02-09T03:31:13Z")

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Hi, I’m currently testing the openMV optical flow on a drone which the camera pointing down to the surface to stabilize the drone. At 3 to 5m above the ground, it works fine. But is it possible to work at the height of 50m.  
Thank you.

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**Author:** ![kwagyeman](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/kwagyeman/32/4_2.png) [@kwagyeman](https://forums.openmv.io/u/kwagyeman)\
**Post date:** [February 9, 2023, 5:18am UTC](https://forums.openmv.io/t/optical-flow-usable-distance/7945/2 "2023-02-09T05:18:25Z")

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Hi, I can’t answer that. I’d do a generic search on the web to see if the technique is valid for that type of distance and what resolution and FPS you need.

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**Author:** ![Lukita](https://avatars.discourse-cdn.com/v4/letter/l/ba9def/32.png) [@Lukita](https://forums.openmv.io/u/Lukita)\
**Post date:** [February 9, 2023, 6:25am UTC](https://forums.openmv.io/t/optical-flow-usable-distance/7945/3 "2023-02-09T06:25:49Z")

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> [@kwagyeman](#):
>
> that. I’d do a generic search on the web to see if the technique is valid for that type of distance and what resolution and FPS you need.

I’m using the mavlink\_opticalflow.py code, in which the resolution is 64x32 and around 25 - 30 FPS. Thank you

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**Author:** ![oramafanis](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/oramafanis/32/1783_2.png) [@oramafanis](https://forums.openmv.io/u/oramafanis)\
**Post date:** [February 9, 2023, 11:08am UTC](https://forums.openmv.io/t/optical-flow-usable-distance/7945/4 "2023-02-09T11:08:16Z")

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what focal length lens work for 5 meters?  
did you try to increase it and test?

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**Author:** ![longwuhen](https://avatars.discourse-cdn.com/v4/letter/l/dec6dc/32.png) [@longwuhen](https://forums.openmv.io/u/longwuhen)\
**Post date:** [October 12, 2023, 7:43am UTC](https://forums.openmv.io/t/optical-flow-usable-distance/7945/5 "2023-10-12T07:43:14Z")

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Is the test continuing? How does it work?