[Radiance-general] materials and texfunc

[Rob Guglielmetti]

Hi Jia,

Some quick answers:

1. The Luxal resource is an excellent starting point for values, but yes measurement of your own samples is the best way. The macbethcal procedure that is documented in Rendering with Radiance is very useful, too. If Ecotect is giving RGB values in the 0-255 range, then yes you would divide the color channels by 255 to get a 0-1 value that Radiance expects. 

2. textfunc is a Radiance material primitive, not a program, so there is no manual page for it. Its use is documented in the Radiance reference manual and several other places. Linkage:

http://radsite.lbl.gov/radiance/refer/materials.pdf
http://radsite.lbl.gov/radiance/refer/refman.pdf

3. To use a .png as a pattern, you need to save it in .hdr format for Radiance to use it. if you first convert the .png to .tiff, you can then use ra_tiff to convert it to .hdr format thusly:

ra_tiff -r pattern_image.tif pattern_image.hdr

Axel Jacobs has some good stuff on using images as patterns in his tutorials.

Hope this helps...

- Rob

On Jul 6, 2010, at 8:25 PM, Jia Hu wrote:

> Hi all:
>  
> I have some questions.
>  
> (1) Besides measure, through which methods I can find the common values of material property, such as RBG, reflectivity and roughness value? I know two places: Colar picker at http://luxal.eu/resources/radiance/index.shtml  and Ecotect which provides some examples, but RBG values are not 0-1, should I divide the RBG value by 255?
>  
> (2) When typing "man texfunc", I can not find the command. Is that my installation problem?  I use ubuntu and Radiance version 4.0.
>  
> (3) Is that right I can add texture and pattern by using procedural functions (e.g. wrinkle.cal) and bitmaps accoring to http://www.artifice.com/radiance/rad_materials.html ?  If I have an image with an .png extension, how can I add the image as the the pattern ?
>  
> Thank you.
>  
> Jia
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