…and not for the first time J
- ½
From:
owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Daniel Rind
Sent: 22-Feb-07 12:19
To: XSI(at)Softimage.COM
Subject: Re: 16bit Zdepth?
Each pixel is sampled at least 22min
times and at most 22max
times in each direction.
The "in each direction" is new I think, that wasn't always there. I
guess it's a typo.
2007/2/22, Halfdan Ingvarsson <hingvars(at)softimage.com>:
Not quite. It's 2^max samples on a side, or in other words:
2^max * 2^max == 4^max == 2^(2*max)
Pretty pictures: http://lamrug.org/resources/samplestips.html
- ½
Also
means that the mental ray docs are wrong.
The pixel
isn't sampled between 2^2*min and 2^2*max times, but between 2^min and 2^max
times. So sampling at 1/1 means 2x2 samples per pixel, not 4x4 like the manual
suggests.
2007/2/22,
Halfdan Ingvarsson <
hingvars(at)softimage.com>:
Mental
ray samples on pixel corners but filters from the pixel centre.
With that in mind, the only way to get a non-shifted, non-blurred,
point-sampled image is to render with sampling at 1/1 and using a triangle
filter at 1. This ensures that only the center sample is used in the final
output, with the rest thrown out.
Unfortunately, it is also hideously expensive.
- ½
-----Original Message-----
From: owner-xsi(at)Softimage.COM
[mailto:
owner-xsi(at)Softimage.COM] On Behalf Of André Adam
Sent: 22-Feb-07 11:54
To: XSI(at)Softimage.COM
Subject: Re: 16bit Zdepth?
The minimum filter range is 1 pixel (radius), and since the samples are
shot in a one-sample-per-pixel raster, the filter will *always* reach
the neighbouring samples. The trick is to use a filter with a
zero-weight at the maximum extent, like triangle or gauss. Box will have
a 1 weight throughout the whole distance, therefore combining the
original pixel's sample value with the neighbouring ones.
Oh, and I guess the jitter option should be turned off for all of this
to work; haven't tried that, but it should cause problems due to the
need for an even sampling raster (see above).
Cheers!
-André
Daniel Rind wrote:
> It's Sampling at 0 / 0, and filter size at 1 (the minimum).
>
> Each pixel is sampled at least 2^2/min/ times and at most 2^2/max/
> times in each direction.
>
> So for 0 / 0 this means 1 x 1, and for 1 / 1 it would mean 4 x 4, or
> 16 samples per pixel.
>
> The filter /shouldn't/ make any difference, but oddly it does. Box
> filtering adds blur and shifts the whole image down and left by half
> a pixel (really odd), so take triangle filtering.
>
> Ciao, Daniel!
>
>
> 2007/2/22, Tim Leydecker < BauerOink(at)gmx.de <mailto:BauerOink(at)gmx.de>>:
>
> Hey,
>
> thanks alot guys! I´ve had great success with a
projection
> of a gradient piped into a constant shader and
that one
> assigned the partition (like it simple, the
backroundpartition).
>
> It´s just that rendering bit that puzzles me. To
rinse and repeat,
> I use Filtering set to 0/0, or is it 1/1?
>
> That´s the bit I don´t get, how to make sure I
have no AA at all.
>
> From there it´s still somewhat challenging to get
the correct
> mapping (e.g. linear instead of gamma corrected)
out of XSI
> but that one I should get together by rendering to
float/linear.
>
> I can´t test the above today since I´m still
working in Maya
> but allready do most of my personal stuff in XSI
(at home) it
> would be great to also optimize that in depth once
and for all.
>
> The more I have the chance to compare the apps,
the less
> satisfied I am with Maya, btw. Especially when
shading and
> rendering with passes in mind. Oh, boy.
Additionally, it´s Maya8...
>
> Cheers
>
> tim
>
>
> ----- Original Message -----
> From: "Joe Laffey" < joe(at)laffey.tv <mailto: joe(at)laffey.tv> >
> To: <XSI(at)Softimage.COM <mailto: XSI(at)Softimage.COM>>
> Sent: Thursday, February 22, 2007 4:18 PM
> Subject: RE: 16bit Zdepth?
>
>
> > On Thu, 22 Feb 2007, Kim Aldis wrote:
> >
> >>> -----Original Message-----
> >>> From: owner-xsi(at)Softimage.COM
<mailto:
owner-xsi(at)Softimage.COM>
> [mailto: owner-xsi(at)Softimage.COM <mailto: owner-xsi(at)Softimage.COM>]
On
> >>> Behalf Of Andreas Bystrom
> >>> Sent: 22 February 2007 13:25
> >>> To: XSI(at)Softimage.COM <mailto:XSI(at)Softimage.COM>
> >>> Subject: Re: 16bit Zdepth?
> >>>
> >>> grab a scalar-state, plug that into a
change_range node and
> finally
> >>> plug the change_range into the
surface port, leave the
> scalar-state
> >>> settings as it is and set
the "new range start" to 0 and "new
> range
> >>> end" to 1 in the change range
node, your old and new-range
> parameters
> >>> should be set to the distance where
you want the depth-pass to
> start
> >>> and end, you can link these 2 values
to nulls with an
> _expression_ and
> >>> use those to control the depth-pass
> >
> >
> >> You may also find that a linear falloff
isn't necessarily what
> you need.
> >> Plugging the output of the change range
into a grad will allow
> you to tweak
> >> it, if you need to.
> >>
> >
> > I think the non-linear mapping would be
better done in the
> compositor, though. That
> > way you have the option of linear or putting
a curve on it.
> >
> > --
> > Joe
Laffey |
Visual Effects for Film and Video
> > LAFFEY Computer Imaging |
> -------------------------------------
> > St.
Louis, MO
| Show Reel http://LAFFEY.tv/?e04685
> > USA
|
> -------------------------------------
> >
.
| -*- Digital Fusion Plugins -*-
> >
>
--------------------------------------------------------------------------
> > Mail here will be rejected --> "Real
Trap" <
> r_trap(at)laffeycomputer.com <mailto:r_trap(at)laffeycomputer.com
>>
> > ---
> > Unsubscribe? Mail Majordomo(at)Softimage.COM
> <mailto: Majordomo(at)Softimage.COM > with the following text in
body:
> > unsubscribe xsi
>
>
> ---
> Unsubscribe? Mail Majordomo(at)Softimage.COM
> <mailto: Majordomo(at)Softimage.COM>
with the following text in body:
> unsubscribe xsi
>
>
---
Unsubscribe? Mail Majordomo(at)Softimage.COM
with the following text in body:
unsubscribe xsi
---
Unsubscribe? Mail Majordomo(at)Softimage.COM
with the following text in body:
unsubscribe xsi
|
