[Radiance-general] Reflectance data

[Greg Ward]

You can use the routines defined in src/common/ccolor.h to convert from spectral measurements to a CIE color and from there to RGB:

#include "ccolor.h"
{
	C_COLOR		clr;
	float				spec_data[MYNWL];
	float				rgb[3];
	double			myLuminance = 0.5;

	/* set spec_data[] array] */
	c_sset(&clr, 344.0, 1045.0, spec_data, MYNWL);
	ccy2rgb(&clr, myLuminance, rgb);
}

Note that you have to decide the number of wavelengths ahead of time, and they must be evenly spaced.

I've arbitrarily set the overall Y value to 0.5, but of course you set it to what you need.  I can't help you with that part.

Cheers,
-Greg

> From: Jia Hu <hujia06 at gmail.com>
> Subject: [Radiance-general] Reflectance data
> Date: September 3, 2014 8:02:35 PM GMT+01:00
> 
> Hello, I use a device to measure the reflectance from 344 to 1045 wavelength, 
> How could I convert these measured data into Radiance RGB,  and how could I calculate the overall reflectance from the measurement?    
> 
> I try to use weights of RGB channels in Radiance, but which wavelength out of 344 - 1045 should I select for each channel?  
> 
> Thanks,
> Jia
> 
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