[Radiance-general] sky mapping

[Giovanni Betti]

Hi Lars, thanks for your reply, I've attached my scene description.
Sorry but I do not have an ftp where to upload them although thwy are
very very small files...

To reply your questions:
I do not have any bright ring in the source image which is an angular
fisheye view (180 fov) generated in radiance of a CIE sunny sky using
the option -s (I do not expect this technique to be of any use for
direct sunlight, only for the diffuse component) the image is uncropped
and the cal file says: Projection of 2d image fisheye picture to source,
applies to angular fisheye like Nikon 180 deg.
Although I cannot find any geometrical distortion, it's only the value
nearby the horizon that goes up.
For point 2, I have the error of 1% nearby the centre (really where the
"sun" should be) and then it goes up as it approaches the horizon...

Thanks,

Giovanni

-----Original Message-----
From: radiance-general-bounces at radiance-online.org
[mailto:radiance-general-bounces at radiance-online.org] On Behalf Of Lars
O. Grobe
Sent: 08 September 2009 19:03
To: Radiance general discussion
Subject: Re: [Radiance-general] sky mapping

Hi!
>
> It seems to work fairly well (the error at the centre is about 1% of
> the original image) but
>
> 1) a bright circle forms along the horizon
>
> 2) the remapped image is constantly less bright than the original one
>
It would be nice if you could share the scene as well as the resulting
image by e.g. uploading it to a web oder ftp server. Please not by
posting any attachments.. If you have a bright ring in the result - do
you have a bright ring in your source image, e.g. at the edge of the
image circle? How did you prepare the image, do you crop it? Does the
cal-file expect a 180 fov. and does your image provide that?

Under 2) you write that the image is less bright then the original, but
at the centre you have only an error of 1% - do you have a constant
error of 1%?

Are you sure that the fisheye projection assumed by the script assumes
your camera/lens projection?

Does the source image include direct sun (visible)?

Cheers, Lars.

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