mapping texture

Hi, all:

I am new to radiance. I have asked one question about mapping texture and thanks very much for your answers. But now I am still not clear about those functions.
I use "frac(U) frac(V) " to tile the texture just like an example I found on the Internet. But I found there are other methods to do so such as "tile_u tile_v". I have searched in the book "Rendering with Radiance", but can not find explanation about it. Also I can not find further explanations of function clip( ) and noop( ). Is there anything I can refer to or are they just somwhere in the book "Rendering with Radiance"?

Would you please help me on this naive question? Thanks a lot.

yours,
Huang

Huang,

the ultimate mapping solution is to use the mesh primitive,

you may create an UV map within your favourite 3D modelling application
and forget about Px Py and all the xform instances....

I use cinema 4d and it works brilliantly... also in conjunction with
bodypaint is a killer...

You may also use the UV map to generate procedural patterns... just
change Px with Lu and Py with Lv....

This is an example:

By means of .obj file format you can import the geometry into radiance:

something like:

obj2mesh -a material.mat model.obj > model.mesh

The obj file includes already the UV coordinate system.

You need just to define radiance materials in material.mat.

If you have a pattern and you want to tile it, just use this syntax into
the material definition:

void colorpict pattern

7 red green blue image.pic . (A*Lu-floor(A*Lu)) (Lv-floor(Lv))

0

0

pattern plastic finalmaterial

0

0

5 1 1 1 0 0

where A is the ratio between the Xmax and the Ymax in the image.

finally you need a radiance file that loads the mesh,

this is achieved with the mesh primitive:

void mesh painting

1 model.mesh

0

0

and so on.

No light sources can be included into meshes, so remember to split your
scene.

hope this helps,

ciao,

giulio

···

________________________________

From: [email protected]
[mailto:[email protected]] On Behalf Of
Huangwx@kyotoUniv.
Sent: 20 July 2005 02:59
To: [email protected]
Subject: [Radiance-general] mapping texture

Hi, all:

I am new to radiance. I have asked one question about mapping texture
and thanks very much for your answers. But now I am still not clear
about those functions.

I use "frac(U) frac(V) " to tile the texture just like an example I
found on the Internet. But I found there are other methods to do so such
as "tile_u tile_v". I have searched in the book "Rendering with
Radiance", but can not find explanation about it. Also I can not find
further explanations of function clip( ) and noop( ). Is there anything
I can refer to or are they just somwhere in the book "Rendering with
Radiance"?

Would you please help me on this naive question? Thanks a lot.

yours,

Huang

Hi Huang,

One good resource, is the file: rayinit.cal, which should be in your lib
directory as well as picture.cal. The former will give you some sense of
what frac(x) actually calculates, the latter will help with tile_u and
tile_v. Picture.cal is the basic procedural function for mapping an
image texture onto geometry using the "colorpict" material modifier
type. The function clip(x) makes sure that the value x is forced to the
range [0,1] while the function noop(v) simply return the value v without
any modification.

Huangwx@kyotoUniv. wrote:

···

Hi, all:
I am new to radiance. I have asked one question about mapping texture
and thanks very much for your answers. But now I am still not clear
about those functions.
I use "frac(U) frac(V) " to tile the texturejust likean example I
found on the Internet. But I found there are other methods to do so
such as "tile_u tile_v". I have searched in the book "Rendering with
Radiance", but can not find explanation about it.Also I can not find
further explanations of function clip( ) and noop( ). Is there
anything I can refer to or are they just somwhere in the book
"Rendering with Radiance"?
Would you please help me on this naive question? Thanks a lot.
yours,
Huang

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Hi Huang.

Sorry for the late reply, I hope you did not despaire yet.

You can find a few of the mapping types illustrated here:

http://home.arcor.de/tbleicher/radiance/imagemaps.html#mapping_types

I wrote this two years ago and can't remember where I got my
information from in the first place; probably try-and-error.

Hth, Thomas

···

On Wed, Jul 20, 2005 at 10:58:32 +0900, Huangwx@kyotoUniv. wrote:

I use "frac(U) frac(V) " to tile the texture just like an example
I found on the Internet. But I found there are other methods to do
so such as "tile_u tile_v". I have searched in the book "Rendering
with Radiance", but can not find explanation about it. Also I can
not find further explanations of function clip( ) and noop( ). Is
there anything I can refer to or are they just somwhere in the book
"Rendering with Radiance"?

Would you please help me on this naive question? Thanks a lot.

Hi Thomas,

this is an interesting amount of work you've put up on your website, for unknown reasons I haven't heard of all this before..

I just started looking at Blender some days ago, and I am currently a bit overwhelmed by it, too. So it's the Blender part of the matter which still
delays any further occupation with it on my side, btw the same holds true for Francesco's work. But there will come the time when I catch up with both of you on this. It would be definitely interesting to connect all our activites in some way...

-greetz
Carsten

Hi,

one hint, the tile-functions are explained (on the really nice webpage,
maybe the most comprehensive page to learn about mapping with radiance) to
give always a square picture. AFAIK that's why one should give the aspect
ratio of the picture on the third line, e.g.

void colorpict mymap
7 red green blue myimage.pic picture.cal tile_u tile_v
0
1 2.5

Hope I'm not wrong, I am currently sitting in an internet cafe in Istanbul
without access to my radiance installation :wink:

Have a nice workshop next week!

CU Lars.

Thanks for that. I didn't try it yet but I'll have to
research this mapping stuff sooner or later in detail
to give a more complete coverage in the page.

Right now I'm having fun with other things, though.

Thomas

···

On Sun, Aug 07, 2005 at 17:29:21 +0200, Lars Grobe wrote:

void colorpict mymap
7 red green blue myimage.pic picture.cal tile_u tile_v
0
1 2.5