I tried to make some graffiti in PS and use it as top texture layer
with alpha channel (from the layer opacity) on otherwise finished
texture. The problem is getting the nice transparent edges to appear
the same in povray. Before the file is saved it must be flattened
and this means there must be some color below the graffiti layer.
That color is the broblem because there isn't a color that will
make the upper layer look right because it will be mixed with
the upper layer and creates a visible edge in the rendered image.

Here is how to export partially transparent layer from Photoshop
with colors and transparency intact.

1. Create new channel from layer transparency:
   Select/Load Selection/Channel: Layer Transparency.
   Click on "Save selection as channel" button on
   Channels window. Select/Deselect.

2. Restore full colors on layer. Repeat the following 8 times:
   Layer/Duplicate Layer. Layer/Merge Down.

3. Layer/Flatten Image. It doesn't matter what is on the bg layer
   because it is completely masked by the alpha channel.

4. Save as 32 bit tga.

Use the tga like this: pigment{image_map{tga "layer.tga"}}.

Anyone know why the top layer finish is applied to all layers? It sure
makes things complicated.


_____________
Kari Kivisalo

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Here's how I make tgas with a partially transparent background.

Create the image on the first layer with a black background (It could be any
colour)
Select the black background
save as a alpha channel mask(button on bottom of channels box)
at this point one could add pattern to the background
remove the selection
make sure the bits you want transparent are black - you may need to invert
the alpha channel
save as 32bit tga
Don't bother to flatten

If you want partial transparency make the black bits of your alpha channel
a grey.

Mick

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Mick Hazelgrove wrote:
> 
> Here's how I make tgas with a partially transparent background.

Consider this. You have image with one transparent layer only. Paint
on it with airbrush. Now try to apply the layer as texture so that
the effect is same as if you airbrushed directly on the texture layer
below. Not so easy.

Here is a pictorial presentation of the problem. The bg color green
could have been _any_ color and it would still show up on the render.
The checker pattern that shows through transparent layers is duplicated
as the bg layer in povray.
http://www.pp.htv.fi/kkivisal/layer.jpg


_____________
Kari Kivisalo

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On Wed, 29 Aug 2001 17:05:17 +0300, Kari Kivisalo
<ray### [at] engineercom> wrote:

>Anyone know why the top layer finish is applied to all layers? It sure
>makes things complicated.

Because it's the first one the ray hits. Being the outermost, and
finish being related to surface properties makes some sense although I
agree about the complicated part.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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"Peter Popov" <pet### [at] vipbg> wrote in message
news:l3iroto55d17qbh27674cmocob1ohgqsho@4ax.com...
> On Wed, 29 Aug 2001 17:05:17 +0300, Kari Kivisalo
> <ray### [at] engineercom> wrote:
>
> >Anyone know why the top layer finish is applied to all layers? It sure
> >makes things complicated.
>
> Because it's the first one the ray hits. Being the outermost, and
> finish being related to surface properties makes some sense although I
> agree about the complicated part.
>
>
> Peter Popov ICQ : 15002700
> Personal e-mail : pet### [at] vipbg
> TAG      e-mail : pet### [at] tagpovrayorg

I've long felt the finish statement should have all of the same mapping support
'normal' and 'pigment' have. I can see where this would complicate the parsing
though, given the large number of parameters possible in a finish statement. The
only workaround I know of uses material-maps, but it sure is expensive with
respect to memory.


--
Batronyx ^"^

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