Reading number plates on a cloudy day

[Luton Driver]

Hopefully you can see this screenshot of footage taken on a cloudy day. This is the tale of two cameras, there is the camera that takes clear photos of number plates of passing cars on sunny days but as soon as the sun goes in number plates become a fuzzy mess. This photo was taken while I was stationary as a lorry squeezed passed yet there is not a single frame where the number plate can be read. The camera has the lasted 3.3 software and uses a filter to cut the reflection. It is also at the maximum quality setting. Is it just me or is this a characteristic of the camera?

 

[Nigel]

I guess from the motion blur that the lorry didn't slow down much

Clearly, from the headlights, it was quite dark at the time, all cameras would have had difficulty.

 

[SawMaster]

100% plate capture is 'the holy grail' of dashcams and is equally findable

Phil

 

[jokiin]

100% plate capture is 'the holy grail' of dashcams and is equally findable

Phil

the holy grail is likely to turn up sooner

 

[Luton Driver]

The photo was taken at 3:15 almost 3 hours before sunset but the sky was really overcast. This is just an example screenshot as I can look at any footage taken on a cloudy day and have the same issue. Would it be any better at 1080p at 60fps rather than the standard 30fps?

 

[Deleted member 46308]

the holy grail is likely to turn up sooner

 

[TonyM]

The photo was taken at 3:15 almost 3 hours before sunset but the sky was really overcast. This is just an example screenshot as I can look at any footage taken on a cloudy day and have the same issue. Would it be any better at 1080p at 60fps rather than the standard 30fps?

The 60fps setting 'can' sometimes deliver better results in these overcast conditions by limiting the exposure time to 1/60s rather than 1/30s. However many cameras drop down to an effective 1/30s in low light and use frame-doubling to generate the 60fps. I can't remember if the A119 does this.

Try parking at the side of a road with generally consistent traffic speeds and switch between modes then compare.

As we go into autumn and winter you may want to consider removing the CPL, since your video may be affected more by the reduction in light than by the reflections the CPL removes.

 

[eezytiger]

It's been cloudy all day here and I thought I'd review some footage from my journey this morning under overcast skies. I use full resolution at 30 FPS and have a CPL filter fitted. My observations are that depending on closing speed between the vehicles there is a variable sweet spot for reading number plates. The faster the approach the more distant the vehicles need to be for a sharp image. The problem here is that the further away the vehicles the smaller the details, so it is worth navigating frame by frame to find the largest frame which is "sharp" enough. It also helps if the approaching vehicle is on a trajectory for a close pass. Not so good if there is a wide separation, e.g. a lane apart.

For example, in this shot my wipers are on intermittent wipe as it is drizzling. This is probably the best frame, with too much blurring as the truck gets closer and details becoming increasingly too small at greater distances. Nonetheless the plate can be made out.

https://photos.google.com/share/AF1...?key=ZXRWYkV1dkVQczF5Y2dDalVfYzc3T05pUjhmSU5B

Some more examples where I picked the "best" frame, so it can be done. Results might improve with the CPL removed as having it fitted will at least halve (or worse) the light available to the camera. Whether things do improve is down to the increase in reflections which might follow.

https://photos.google.com/share/AF1...?key=VUIwaGxOOVd1elRyZngweHIzY1dTb1RKYjlib3Zn

https://photos.google.com/share/AF1...?key=Z0ktam5iY21ublZsYXlQZzA1X0VvdTFLTkdub3N3



As speeds increase quality of results can be expected to fall.

 

[lacibaci]

Need bigger sensors, more pixels and better lenses

 

[Tatty]

Viofo 119 uses the same trick as many cameras today.Because of the tiny lens,when set to 60 FPS you really need a very good light to catch the plates number of moving cars.Even in bright lighted areas,this is impossible for fast moving cars (80 km/h or more).The situation is even worse in low light,because the camera is lowering the fps to 30,and if that is not enough the exposure time for the 30 fps is increased,which in fact has the result of making a blurry image.You should have for this sensor size at least 40mm lens diameter to have a useful image at night and a sharp recording of fast moving objects.But this lens will obviously cost more than the camera itself...

 

[ChannelZ]

This is why the Transcend DrivePro 200 was such a good camera for picking up number plates - a big lens. Shame it was pretty rubbish otherwise - 32GB card limit, wobbly fixed mount, and mine developed an audio rattle and also shimmery video (like videoing a constant heat haze).

 

[eezytiger]

Even at the pricier end of the spectrum results can be poor....

But also quite variable - sometimes good, sometimes less so.