[Radiance-general] Textures: perturbations in x,y,z normals

[alira at gsd.harvard.edu]

Hi Greg,

In effect, what I get is the resemblance of a shpere the larger the
object. For this reason, I feel that I'm using "texfunc" in an improper
way for what I need. My objective is to modify the x, y and/or z normals
of a surface in order to analize how much R, G and/or B is being
absorbed/reflected. I know that depending on the texture of a surface, for
example, shortwavelenghs of the spectrum are more reflected than the short
waves of the spectrum. What I need is to create a "bumpy" surface in order
to see how much blue is reflected depending on the scale of this
"bumpiness" ( from very small scale-microscale, if possible, to
macroscale) and by having control of the perturbation of the x, y and z
normals. Is there a logic way in how to do this?

Adriana


> Hi Adriana,
>
> What do you want your surface to look like?  What do you want your
> normals to do?
>
> The string arguments of the "texfunc" primitive define expressions
> for a "perturbation" of the surface normal, i.e., a value to be added
> to the default surface normal.  In your example, depending on the
> values of A1, A2, and A3 (and assuming "PZ" should have been "Pz"),
> you would get a surface normal that would change gradually according
> to the position in 3-dimensional space, forcing whatever object was
> covered to have a surface normal resembling that of a sphere the
> larger the object became.  This seems a very strange goal to me.
>
> -Greg
>
>> From: alira at gsd.harvard.edu
>> Date: April 24, 2006 12:17:50 PM PDT
>>
>> Hi all,
>>
>>    I want to experiment with the texture of the materials by
>> modifying the
>> x, y and/or z normals of the surfaces in order to see how the
>> reflected
>> light changes in its characteristics. However, when I modify the
>> normals, using texfunc as the following example, apparently, just the
>> main normal is modified.
>>
>>    void texfunc id
>>    3 Px*A1  Py*A2  PZ*A3
>>    0
>>    3 A1 A2 A3
>>
>>    Does anyone have any suggestions on how I can make a "grid of
>> normals"
>> in order to modify the normals of smaller regions of the surface? and
>> how can I change the scale of that "grid"?
>> Thanks in advance,
>>
>> Adriana Lira
>> Master in Design Studies, 2003
>> Candidate for Doctor in Design Studies
>> Harvard Graduate School of Design
>
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Adriana Lira
Master in Design Studies, 2003
Candidate for Doctor in Design Studies
Harvard Graduate School of Design