Embedded Alpha channel is ignored

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AStef AStef
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Embedded Alpha channel is ignored

Hi,

I have some image (png or tiff) with embedded alpha/transparent pixels. They are always displayed as fully opaque by the gdal driver.

I'm aware of the "opacity" tag for "image" but it change the opacity as a whole. And using the "transparent_color" tag does not fit my needs, as it leaves some nasty colored pixels around masked out zones (as if the image was anti-aliased by osgearth *before* alpha-test)

Did I missed something? (note I'm using a FadeLayerNode, if that helps...)

thx
gwaldron gwaldron
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Re: Embedded Alpha channel is ignored

Does it appear correctly without the use of FadeLayerNode?

Glenn
Glenn Waldron / Pelican Mapping
AStef AStef
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Re: Embedded Alpha channel is ignored

No, I have the same visual output with or without a FadeLayerNode.

Note: I use
<layering_technique>multipass</layering_technique>
along with the FadeLayerNode. Is this correct?
Also, can
<loading_policy mode="preemptive"/>
 be used along them?

Thx
jasonbeverage jasonbeverage
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Re: Embedded Alpha channel is ignored

Hi Asteph,

The FadeLayerNode isn't compatible with the multipass mode since the
FadeLayerNode expects multiple texture units to be used and in the
multipass mode only a single texture unit is used.

Preemptive mode isn't compatible with the multipass mode but should
work fine with the FadeLayerNode.

Thanks,

Jason

On Wed, Jul 21, 2010 at 11:52 AM, AStef [via osgEarth]
<[hidden email]> wrote:

> No, I have the same visual output with or without a FadeLayerNode.
>
> Note: I use
>
> <layering_technique>multipass</layering_technique>
>
> along with the FadeLayerNode. Is this correct?
> Also, can
>
> <loading_policy mode="preemptive"/>
>
>  be used along them?
>
> Thx
>
> ________________________________
> View message @
> http://forum.osgearth.org/Embedded-Alpha-channel-is-ignored-tp5321390p5321646.html
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