OV7251 tracking cam focus
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Is the OV7251 fisheye tracking cam supposed to be somewhat out of focus rather than being very sharp?
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@hmlow , the fisheye cameras typically have very short focal length and for OV7251 (fisheye version), anything that is farther than approximately 15cm (6in) away or even closer should be in focus for this camera. If you have a specific concern, please post an image capture with two high contrast objects : one 15cm away and one 1m away. Double check to make sure the lens is not dirty, otherwise you may gently clean it with a very soft microfiber cloth. Keep in mind the lens is made of plastic, not glass, so it can be scratched if you don't use a soft microfiber cloth.
If you have another identical OV7251 camera, you can compare them to check if the image looks similar.
Alex
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These two below are captured from a custom drone that is known to fly reasonably well in feature rich indoor environments.
When flying outdoors, even if the scene is feature rich and QVIO is actively tracking 20+ features, the quality drops drastically (to -1) if they are far away like more than 200m away. I have at least 10 identically built so far and they exhibit similar behaviors indoors/outdoors.The Murata box is placed at around 20cm and 60cm respectively:
I wont consider the lens to be sharp as you can hardly make out the words "murata" at 60cm. Got me thinking if the poor outdoor performance is due to the lenses being poorly focused.
Then, these two below however are taken from a brand new builds:
This im quite sure has got something wrong with the lens/focus isnt it?
I dont think the lens can be adjusted in the first place. -
Supplementary post to elaborate what i mean when i said that the VIO works well indoors but Qual drops instantly when the features are far away. The images arent exactly sharp:
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@hmlow , the second set of images (which looks blurry) is definitely not OK. Can you check if the lens is clear and not scratched? The lenses n fisheye ov7251 cannot be adjusted as far as I know, but i will double check.
Regarding far away features, this is normal behavior. If VIO only has features that are far away, it cannot determine their position in space unless there is significant motion (to help triangulate the features). In the capture you provided, there are only features that ate far away and none that are close, so those far features are not very useful (at least for position, but they are good for orientation).
Also the test case is not very realistic, if you just have camera looking out of the window at far features and not move anywhere. If the drone was able to actually fly out of the window (not suggesting that
), the motion would allow it to triangulate the features better and pick up new features.Ideally there should be features present both close and far so you will get really good position and orientation estimates from vio.
Alex
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Yes the lenses is clear and unscratched.
I just tried gently rotating the lens and it does rotate!
I have not tried rotating the rest of the OV7251 cam lens in case i end up inadvertently damaging them.Regarding your point about flying out the window -
I have flown these aircrafts outdoors before and even with motion, for as long as the features are far away, the quality metric is bad.However, i noticed that the quality metric shown here remains extremely good even though the features are more than 100m away:
https://forum.modalai.com/post/11882
Two key difference here though:
-OV9782 is used (higher resolution)
-Sharper images (you can see that the entire frame is sharp vs the regular OV7251 where the corner/edges are always soft (pillars in the opposite bldg)Should the OV7251 (even the regular, working ones) be better focused?
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@hmlow , the focus on the non-blurry image looks fine. Keep in mind that the resolution of the image is low (640x480).
If the blurry camera lens rotates (it should not), it is possible that it was not correctly focused during production, so I think you have two choices:
- try to focus it yourself (and then you would need to glue it in place (i will need to check what adhesive can be used to secure the lens, but do not use CA / super glue)
- return the camera and we can send you a replacement part
Please let me know what you would like to do.
Alex
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@Alex-Kushleyev I'll glue it back in place myself. Thanks!
