Hi all, I have a project based on live logging of luminance of streets on drive. How I can do it with an Arduino based system? Any Help??
Do you need to measure absolute values or are you just interested to know that lamp A is 50% brighter than lamp B.
The latter is relatively easy to do with a Light Dependent Resistor but I have no idea how you could calculate absolute values.
Tell us more about your project.
You can use this Adafruit TSL2561 Digital Luminosity/Lux/Light Sensor Breakout
That looks like a very useful device. I may even get one myself to measure the output of my LED lamps - I suspect it declines significantly with age.
However, AFAIK lux just tells you the intensity at a specific location whereas the true output of a lamp is the integral of the lux values over the surface of a sphere or hemisphere. Lamp manufacturers like to keep us in the dark.
Please define further. You might want to look at the sd card which is an extra bit. Alternatively, raspberry pi has a large enough sd card and a 32 bit operating system suited to work as a web server. What do you mean by "live" ? If you are talking about logging and immediately appending to a chart on a web page the average light level every minute for a month, you also need to think about weatherproof boxes and which parts to locate indoors and outdoors.
I'd be using the Adafruit sensor (with a (black) Elizabethan collar), then pointing that directly up at the lights as i passed. Almost any arduino plus a GPS/SD shield, then drive around all you like. Logging the location*, time and light levels.
All you have to do is make sure you're under the lights. The logging could be continuous, or triggered with a button press, or peak trigger on adjacent sample values.
There! done. * yes, you can reconcile the sample locations on Google maps for a real-world plot of relative levels.
lastchancename: then drive around all you like. Logging the location*, time and light levels.
All you have to do is make sure you're under the lights.
Sounds very hit and miss to me.
Sure the OP would have a collection of numbers. But whether the numbers mean anything useful is an entirely different matter.
The OP has not told us how he intends to use the data.
Sounds very hit and miss to me.
I believe the collection mechanism is legitimate, but what protocol he uses to collate and filter/process the data is entirely subjective. Cheers
lastchancename: I believe the collection mechanism is legitimate,
I wonder ...
Won't there be different values depending on how far the sensor is from the light source?
The OP will know how much light falls on his sensor, but he won't know much about the street lamps.
If he's driving at street level with the 'collector' pointing straight up, and passes directly beneath, or as close as feasible to all the lights, the results will be relevant to the light falling on those same points in the varying circumstances. I believe close-enough for typical auditing... but it won't 'see' dead lights! He needs a logging button for that!
Some light poles will be taller etc, but the light on the road will be scaled & distributes appropriately - based on the light output, height, lens, offset etc. To account for all those (see below).
Yes, there will be spill from other light sources / night sky etc - so OP has to narrow the field of view etc.
The onjy other way i can see to be very accurate, would be to throw a light blanket over each luminaire, and poke the sensor up next to the light source !!!?
I don't disagree with anything in Reply #9 but, as we have not heard from the OP we don't know what he would like to do with the data.
He doesn't need an Arduino if the only purpose is to report failed lamps to the Local Authority or whoever is responsible for maintenance.
But if he wants to compare Lamp Brand A with Lamp Brand B or compare the actual output to the manufacturer's specification the data will not be good enough IMHO.
In the UK it would be virtually impossible to drive a vehicle with any part of it directly below a lamp without driving dangerously.
My own slight interest in the lux detector in Reply #2 is to monitor the performance of LED lamps in my boat. In that case I have complete control of the test conditions.