How dark may photos be


#1

It is getting winter again and the days are getting shorter and shorter.
I do a lot of my mapping after work and a relevant question is, how dark may photos be, before they become unusefull.
I took a sequence this week and didn’t upload all photos, because it was getting really dark (around 16:30)

Where should we draw the line, and does it mather if the location already is mapped or not?

Please come with your own exempelphotos


#2

I would say once it’s too dark for your camera to keep up without blurring, that’s the level of darkness that’s good. In your examples, I would say 1 and 2 are fine, but the last 4 are getting too blurry to be useful (#3 is okay…). Sure, you can vaguely see some features, but if there are signs, I can’t read them.

In this sequence of mine, I started riding home at 16:55 in February. I finished at 17:34, sunset at 17:36.

This is the beginning:
https://www.mapillary.com/app/?lat=40.72428055555556&lng=-77.93255277777779&z=17&pKey=fVgaaaUMJ1YJ0_a0H1PB6w&focus=photo

This is right near the end, when I shut off the camera because I felt it was getting too dark:
https://www.mapillary.com/app/?lat=40.81774722222222&lng=-77.85126666666666&z=17&pKey=ESh7PVkLmarzYw-MtvPHLQ&focus=photo

Then again, I’ve had problems with blurring on reasonably bright days on hikes in the woods, so it’s not easy to judge darkness. Our eyes are too good for that. But generally speaking, I find that between sunrise and sunset are good. If my bike GPS switches to night mode, I know it’s probably too dark.

I know we say that anything is better than nothing, but if that anything is really blurry, I’m not too sure. Your last photo shows that the road is probably asphalt, but that’s pretty much all you can get from it.


#3

Both your photos are still perfect I would say.
I took the photos I showed on last wednesday, and I was to lazy to turn the camera off. The sequence I upploaded ended between photo 2 and 3, but it has som dark sequence in the forest.
But that the only use for the dark photos is that you see it is asphalt is mot true. You see there are no streetlights and maybe you could see how reflective the roadsigns are


#4

As long you can read the traffics signs with the natural light, photos are bright enough I’d say.


#5

You can also see the number of lanes, the type of divider. I agree with the general notion that even bad photos are better than none. Even from the low quality ones, a lot of information can still be taken. Now if there already are daylight photos available for this road then I’d say you don’t need to upload these photos, but elsewise they are valuable.


#6

Too dark for what? Both people and AI has a variety of uses for these photos. There’s still a lot of information in those blurry ones.


#7

https://www.mapillary.com/app/?lat=36.028075&lng=-83.87621944444444&z=17&pKey=xywX9pTqjKWMh2ViEgzf9g&focus=photo.

https://www.mapillary.com/app/?lat=41.39491944444447&lng=-87.32614722222222&z=17&pKey=CINP6mN23KxMFBD0u3tBPA&focus=photo


#8

This is one I struggle with a lot, too. I often end up taking sequences when it’s “too dark” so I have data to update OSM with. Unfortunately, they tend to be in less-traveled areas that I know I won’t get back to anytime soon. So then I have to decide when to stop uploading. :frowning:


#9

My smartphone has a luxmeter.


#10

After reading this thread I started my phone/camera going this morning more than an hour before the sun rise. I was surprised the amount of information one can get with high beams on back roads.
If this morning’s pre dawn pictures are of no use, someone can toss them.
I did this as an experiment.


#11

I am lucky that my work is not in the East neither my family.
If you want to take the sun in account planning a trip, use suncalc and the weather forecast.
Or mooncalc :smile:


#12

I run out to Iowa tomorrow. It will be dark on both ends. Memory and uploading will be my limitations.


#13

I know the night pic thing / blurry / not great photo thing is up for debate. One of my thoughts has been it’s about data for the AI, for the computers. They may not be able to do something now with them but down the road they may be useful.

I just noticed on the speed limit 35MPH game that the AI is able to figure out the speed limit sign despite it being night. Sweet, eh? :slight_smile:


#14

With respect to “how dark” I agree that at some point dark photos will be useful. However, while they’re still working on getting the image interpretation bit working, it’s probably best to have bright, high-quality pics so they can…well, figure out how to get it to work.


#15

So there is no excuse for making pictures which hurt the eyes ?
Do they still advise one picture survey a month, or may we take pictures as fools ?


#16

I’m not sure what that means, @JackTheRipper. As shown, they’re able to interpret dark pics.


#17

I keep my camera rolling every day. There may be some bit of value we may never know about.


#18

@allen What I meant was that, while they are still working on getting image interpretation implemented, it is generally best to have high-quality pictures to test on. Once they get it working well with high-quality pics, then they can start on lower-quality (and darker) pictures and get interpretation working on those, and so on.


#19

And don’t forget the humans. I would not want to be a Chinese professional mapper who has to look at …'s highway pictures.


#20

There are now 6 pictures of increasing blurri-ness in the original post. I’d say first 5 are definitely useful, assuming there are no other recent pictures on that road. For example, on the 5th you can see that the buildings exist, and you can map building:levels for them. That’s very useful, especially if those are the only images in the area.
The 6th one is a bit less so. If you are in some super-remote place, it would still be something, but I’d probably not upload it in Europe :slight_smile: