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Josh Yu
Josh Yu
Associate II
March 24, 2018
Solved

VL53L0X Calibration Target - What to use?

Posted on March 24, 2018 at 14:24

The user manual mentions using one 88% reflectance target and 17% reflectance target for calibration. I don't know what material has those reflectance values. What exactly should I use for calibration and where can I get those?

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John E KVAM
John E KVAMBest answer
ST Employee
May 7, 2018
Posted on May 08, 2018 at 01:26

It’s called Munsell Color Paper

X-rite Inc

4300 44th street S.E.

Grand Rapids, Mi 49512

Tel 877-888-1720

The stuff is expensive. Like $26 per sheet expensive.

We use 5%, 17%, 42% and 88% reflectances in our testing. One color per sheet.

MUNSEL NOTATION N2.75/

STM275MA4

5% REFLECTANCE

STMN475/MA4

17% REFLECTANCE

STMN95/MA4

88% REFLECTANCE

STMN675/MA4

42% REFLECTANCE

But standard Photo grade white paper is close enough to 88%, that it will work unless you are really particular.

Black spray paint is 5% reflective. Use a couple of coats. Doesn't matter if it's flat or gloss.

I don't have a good source of 17% gray.

If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.
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4 replies

Anonymous
March 24, 2018
Posted on March 24, 2018 at 22:07

Hello,

Have a look at this lecture presentation: 

https://www.cs.cmu.edu/afs/cs/academic/class/15462-f09/www/lec/lec8.pdf

 

Also, Wikipedia offers quite good explanation: 

https://en.wikipedia.org/wiki/Reflectance

 

However, I wasn't able to find some online trustworthy database of reflectance of various materials.

David

Josh Yu
Josh YuAuthor
Associate II
March 25, 2018
Posted on March 25, 2018 at 05:25

Thanks David! The two links you posted explained what reflectance is pretty well. It sounds like the white target is probably something opaque and with a smooth surface finish. And the dark target is probably something with a rougher finish?

I found this chart on Google. I don't know how trustworthy this is but I thought it was interesting enough.

https://www.automation.com/images/uploaded/chart1.bmp

Josh Yu
Josh YuAuthor
Associate II
March 26, 2018
Posted on March 26, 2018 at 05:46

I've found this sentence from the VL53L0X datasheet (under 'Performance' -> 'Measurement Conditions'):

Reflectance targets are standard ones (Grey 17% N4.74 and White 88% N9.5 Munsell charts).

So it seems like the targets are Munsell color cards. Now the problem becomes how to get those color cards... A quick search online only reveals small pocket sized color cards, which is probably not big enough...

John E KVAM
John E KVAMBest answer
ST Employee
May 7, 2018
Posted on May 08, 2018 at 01:26

It’s called Munsell Color Paper

X-rite Inc

4300 44th street S.E.

Grand Rapids, Mi 49512

Tel 877-888-1720

The stuff is expensive. Like $26 per sheet expensive.

We use 5%, 17%, 42% and 88% reflectances in our testing. One color per sheet.

MUNSEL NOTATION N2.75/

STM275MA4

5% REFLECTANCE

STMN475/MA4

17% REFLECTANCE

STMN95/MA4

88% REFLECTANCE

STMN675/MA4

42% REFLECTANCE

But standard Photo grade white paper is close enough to 88%, that it will work unless you are really particular.

Black spray paint is 5% reflective. Use a couple of coats. Doesn't matter if it's flat or gloss.

I don't have a good source of 17% gray.

If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.
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