Re: Unwrapping chrome ball pictures...

[Francois Lord <francoislord(at)gmail.com>]

What is called a light probe in HDRShop is effectively a lollipop 
projection.
From the HDRShop site:
"The angular map format is similar to the mirrored ball format, except 
that the radial dimension is mapped linearly with angle, instead of 
getting squished towards the edge of the circle like the mirrored ball; 
this gives you better sampling around the edges."

In the interface, angular map is called "Light Probe (Angular Map)"


Schoenberger wrote:
> I would say that lollypop is not the same as a lightprobe projection.
> With a lollypop projection a pixel distance on the image is always the same distance on the sphere.
> (if you take the main directions right-left or top-bottom)
> With a lightprobe the distance on the sphere increases the more you get to the rim of the sphere.
>
> Holger Schönberger 
> technical director
> The day has 24 hours, if that does not suffice, I will take the night 
>
>  
>
>   |> -----Original Message-----
>   |> From: owner-xsi(at)Softimage.COM 
>   |> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Francois Lord
>   |> Sent: Thursday, June 01, 2006 6:17 PM
>   |> To: XSI(at)Softimage.COM
>   |> Subject: Re: Unwrapping chrome ball pictures...
>   |> 
>   |> The lightprobe projection is natively supported by mental 
>   |> ray and is 
>   |> called lollypop. It would only be a matter a writing an 
>   |> environment 
>   |> shader with that projection. however you would still need 
>   |> to convert the 
>   |> mirror ball picture to light probe format.
>   |> If someone knows the calculation required in this 
>   |> conversion (HDRShop is 
>   |> not open source, unfortunately), it might be possible to 
>   |> have the birror 
>   |> ball projection directly in the shader.
>   |> 
>   |> Martin Belleau wrote:
>   |> > That's a very good question... In another software 
>   |> package, for HDR, they
>   |> > have  "Light Probe" as a projection which automatically 
>   |> unwraps the image.
>   |> >
>   |> > Is it possible to do this with an existing Node?
>
>
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