Talk:Key:lit:perceived

Verifiability and other problems

Personally, I do find this key very subjective and calls for a lot of interpretation. For example: when is something 'daylike' or 'minimal'?

1. Minimal for one person is not the same as another and depends on what one wants to do.
2. For example: "Modern lighting fixtures emitting daylight like light, spaced densely enough". What is 'densely enough'? Every 5 meters, every 25? What is modern? This is a moving goalpost too.
3. "lighting is sufficient for you to recognize people's faces": not everyone has equivalent eyesight....
4. At last: "lit:perceived=colorless: Motorway-like light source (mostly Sodium-vapor lamp): amount of light is good but landscape appears colorless, making it a dull experience": this is problematic as well: this is a different aspect (street lighting color instead of brightness), and might not be verifiable by a colorblind person.

Pietervdvn (talk) 19:16, 30 November 2021 (UTC)

The text and the examples were written to try to address these concerns, but probably there's room for further clarification, and example pictures. Admittedly one could refer to technical road lighting standards, but they're mostly concerned with the evenness and minimum lighting levels, and the defined levels don't cover the full spectrum of present installations (from "further away from a dim lamp" to "like commercial indoor hallways"). And making a purely measurement based categorisation might have other uses, but is not directly related to the perception of lighting, and is way much more work to collect.

• In the context of street lighting, the objective is to use the road/way, so minimal refers to seeing the road as a pedestrian (so without your own light source); surface and obstructions, compared to a pitch black forest road away from light pollution.
• Modern could be reworded to LED or other high colour rendering index light source. Sufficient density depends on installation height and luminaire, so what counts is the evenness and for example the fact that an approaching persons face doesn't get unobservably dark when they're between some lamp posts - in urban settings the light can come from so many directions simultaneously that you don't only have a single line of luminaires.
• about the face recognition, it's about the fact that if you can recognize faces at a greater distance in daylight, the lighting has to be sufficient to be able to recognize the same face at the same distance. And likewise, telling red buildings apart from green buildings might be impossible for colorblind, but there's no problem tagging green and red buildings with facade colors, for example.

Alv (talk) 14:00, 12 December 2021 (UTC)

I agree to Pietervdvn we shall further improve definitions in the sense making them less subjective and interpretaion-dependant but more verifiability, inter-subjective.

1. @minimal: Current definition "one can see the ground if they're not an elderly person or otherwise visually impaired, but most people would have to focus on watching their steps" is IMHO a too faint hint that only major edges & structures like a step or a kerb=* shall be recognizable by eyes, but not ground details like stone type of surface=paving_stones, or whether surface=asphalt is smoothness=excellent or smoothness=good, or that recognizing dog's excrements will be quite difficult. Do you think explicitly mentioning this will help to achieve a more homogenous tagging?
2. @daylike: I like the approach by Alv to use a) high CRI (I'd throw in "at least around 80" as a threshold which is used in EU directive 1194/2012) as more objective & stable alternative to term "modern" and because CRI is in fact a relation to daylight thus has a connection to the value's name and b) a mostly even/constant lighting of the ground as criterion for "dense enough". Any concerns or opposing views? :-)
3. @"recognize faces" and "varying eyesight". Eyesight shall IMHO be moved out of single values (e.g. "if they're not an elderly person or otherwise visually impaired") to the overall definition, so all values have the same base reference – which is IMHO important to avoid in the long term two categories do overlap because of different reference base. How do you see this?
4. @colorless: Many pedestrian areas/streets with shops I know actually use Sodium-vapor lamps, and both definitions allow to recognize faces, so current definitions of "colorless" and "good" are overlapping. To make differenciation more clear, I suggest to add a CRI treshold (like with "daylike" but here 50 (so of bad Fluorescent lamp) seems sufficient) to tell apart. To make it even more clear that both are just color variances of good brightness level, I've the impression to reword "colorless" to "good_colorless" could be a simple yet helpful way. What do you think?

And maybe, after these refinements, we shall start a RfC to move direction "approved" in order to get it reflected in applications like StreetComplete or routers, so this tag becomes more useful. --Schoschi (talk) 20:19, 20 November 2022 (UTC)