[Radiance-general] Ambient exclude transfomed materialin instances
Jack de Valpine
jedev at visarc.com
Tue Apr 3 19:40:21 CEST 2007
Hi Giulio,
I just checked out your RadBlog. There are some nice tips, tricks and
hints here.
Best,
-Jack
Giulio Antonutto wrote:
>
> some UV stuff here and hopefully not too many mistakes...
>
>
>
> http://web.mac.com/geotrupes/iWeb/Main%20site/RadBlog/3690C181-7F9F-43AD-B5B2-A5D239AD503E.html
>
>
>
> G.
>
>
>
>
>
> ------------------------------------------------------------------------
>
> *From:* radiance-general-bounces at radiance-online.org
> [mailto:radiance-general-bounces at radiance-online.org] *On Behalf Of
> *Jack de Valpine
> *Sent:* 03 April 2007 18:10
> *To:* Radiance general discussion
> *Subject:* Re: [Radiance-general] Ambient exclude transfomed
> materialin instances
>
>
>
> Hi Iebele,
>
> To use local u,v coordinate mapping (Lu,Lv) you need to use obj2mesh
> rather than obj2rad.
>
> Here is the process for making a mesh element:
>
> Define mats.tree.rad using simple materials first as an example. The
> names of the materials must correspond to the names of the materials
> indicated for the .obj geometry (take a look in the .mtl file to get
> the names).
>
> mats.tree.rad:
>
> void plastic Bark
> 0
> 0
> 5 1 1 1 0 0
>
> void plastic Leaf
> 0
> 0
> 5 1 1 1 0 0
>
> Generate tree.rtm as follows:
>
> obj2mesh -a mats.tree.rad tree.obj > tree.rtm
>
> Creat tree.mesh.rad as follows:
>
> tree.mesh.rad:
>
> void mesh tree
> 1 tree.rtm
> 0
> 0
>
> Test you mesh:
>
> objview tree.mesh.rad
>
> Now lets apply more complex materials using local u,v coordinate
> mapping. To do this you need the following image data:
>
> 1. bark.pic
> 2. aspect ratio for bark.pic (y/x), lets call it <arB>
> 3. leaf.pic
> 4. aspect ration for leaf.pic (y/x), lets call it <arL>
> 5. leaf.matte.pic - this is the alpha/matte channel for the leaf.
> The correct way to setup the matte is for white to represent
> the leaf and black to represent what is not the leaf. This means
> that you may have to invert the matte the comes from xfrog.
>
> Now lets create the complex materials in mats.tree.rad
>
> mats.tree.rad:
>
> #BARK definition
> void colorpict bark.tile
> 7 red green blue Bark.pic . frac(Lu) frac(Lv)*<arB>
> 0
> 0
>
> bark.tile plastic Bark
> 0
> 0
> 5 1 1 1 0 0
>
> #LEAF definition
> void colorpict leaf.tile
> 7 red green blue Bark.pic . frac(Lu) frac(Lv)*<arL>
> 0
> 0
>
> leaf.tile plastic leaf.map
> 0
> 0
> 5 1 1 1 0 0
>
> leaf mixpict Leaf
> 7 leaf.map void green leaf.matte.pic . frac(Lu) frac(Lv)*<arL>
> 0
> 0
>
> Now recompile your mesh:
>
> obj2mesh -a mats.tree.rad tree.obj > tree.rtm
>
> Now view it:
>
> objview tree.mesh.rad
>
> You should add Bark and Leaf to your ambient exclude file/list if you
> do not want them in the ambient calculation. You can use tree.mesh.rad
> along with replmarks, xform or some other method to deploy the tree
> object in the scene.
>
> This should work fine. Let me know if you have any questions.
>
> -Jack
>
> Gregory J. Ward wrote:
>
> Hi Iebele,
>
> I can't be much help on this, as I'm not familiar with the model, but
> the general idea with local coordinates is that you don't have to do
> the mapping yourself. It's supposedly handled by the mesh generation
> software, and isn't affected by transformations as a global coordinate
> mapping would be.
>
> I hope this is a helpful clue, as it's about all I have to offer.
> -Greg
>
>
> From: iebele <info at iebele.nl> <mailto:info at iebele.nl>
> Date: April 3, 2007 8:39:12 AM PDT
>
> Thanks Greg an Jack for your excellent and very helpfull suggestions.
>
> I now have succesfully converted the .obj file to rad, using obj2rad (
> polytrans did indeed work with Xfrog obj-files, but meshlab did not
> accept these files Lars ).
>
> However I can't get the mapping right. I've tried a lot, but with no
> succes. Would you please share with me an example of the materials you
> use for the bark and the leaves?
>
> I just don't really understand when and how to use Lu and Lv or
> frac(Lu) and frac(Lv) in the colorpict modifier and how these can ever
> be placed in a reasonable way on each triangle in the output of
> obj2rad, which in my case is like :
>
> leaf_col_leaf2 polygon leaf22836.60976
> 0
> 0
> 9
> -0.250204 0.195593 13.838
> -1.00383 -0.956752 13.8816
> -1.21881 -0.19178 13.5622
>
> I never really understood the meaning of texture-coordinates, but at
> this time I feel that is what is missing here.
>
> Is there a difference in using obj2rad and obj2mesh for this purpose ?
> I tried both but with the some odd results concerning the coordinate
> mapping.
>
> -Iebele
>
>
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>
> --
> # Jack de Valpine
> # president
> #
> # visarc incorporated
> # http://www.visarc.com
> #
> # channeling technology for superior design and construction
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--
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#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction
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