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1

Wednesday, May 27th 2009, 4:20pm

Sampling and FOV

Hello,

How is the sampling done when you transform a sphere to a cube pano? I have an 8k x 4k sphere panorama that I wanted to downsample to 512 cube faces. The scene has some people with striped tops, and trees, and it looks very aliased, almost as if the sampling were nearest neighbor.

I have not tried the -oversample option, but wasn't sure what to input. Is the oversample the size of the destination panorama width (a cube side, or the whole sphere width)? Or is a factor (oversample by 2x, 3x, etc)? And does oversampling create larger version of the destination panorama, then resize it down? If so, shouldn't there be an option to determine the downsampling method, like the -filter option in kmakemultires?

Finally, with the "view" mode is the FOV horizontal or vertical?

2

Tuesday, June 2nd 2009, 12:38pm

Hi,

currently only "linear" filtering between the source pixels is used, no "sampling" when the output is smaller,

"oversample" will internal render it a high resolution and then downsample it with the lanczos filter, this was intended to use when the output size was set to a much smaller size then original one to avoid aliasing,
in your case (a 512 cubesize from 8192x4096) I would recommend using a oversample value from 2 to 4,

the fov in the "view" mode is vertical one,

best regards,
Klaus