[Bf-committers] A new photo format

Lars Krueger lars_e_krueger at gmx.de
Fri Jun 24 09:21:55 CEST 2011


-------- Original-Nachricht --------
> Datum: Thu, 23 Jun 2011 10:33:16 -0400
> Von: Shaul Kedem <shaul.kedem at gmail.com>
> An: bf-blender developers <bf-committers at blender.org>
> Betreff: Re: [Bf-committers] A new photo format

> This is insane. I wonder if you can derive better meshes or alpha maps
> from this.

The camera does not obtain 3d information. Neither does it capture sufficiant info to compute a depth map. You would still need two of them and do stereo. However, a stereo light field would be incredibly cool.

> 
> Also, this can add to image tracking techniques and 3D objects in
> 2D+lightmaps images/movies.
> 
> Just hope it's as good as it seems :-)
> 
> On Thu, Jun 23, 2011 at 10:19 AM, Lars Krueger <lars_e_krueger at gmx.de>
> wrote:
> >
> > -------- Original-Nachricht --------
> >> Datum: Thu, 23 Jun 2011 10:50:04 +0200
> >> Von: Knapp <magick.crow at gmail.com>
> >> An: bf-blender developers <bf-committers at blender.org>
> >> Betreff: [Bf-committers] A new photo format
> >
> >> Is it possible to get blender to do this?
> >> http://www.lytro.com/picture_gallery
> >
> > short version: Yes, all effects can be rendered.
> >
> > long version: If you read the thesis, you'll see that the camera is a
> technically a plenoptic camera. That means, in very simple terms, for each
> group of pixels, e.g. 16x16 there is an individual lens that focuses the
> light from the main lens (that is similar to a conventional camera) so that the
> whole image fits onto the 16x16 pixels.
> >
> > The effect is that you get lots of 16x16 pixel images that look in
> slightly different directions. If you know which pixel looks where, you can do
> compute something that is called a light field.
> >
> > A light field records for each pixel from which direction what amount of
> light was received. Given the light field, there are algorithms to
> different things: shifting the focus to the front, or the back, or focussing the
> whole image.
> >
> > In a conventional camera, you have to decide if you want to focus on the
> foreground or on the background. You have to select an aperture. All this
> is mechanics, little motors shifting around pieces of glass. In other
> words: It takes time.
> >
> > Other drawbacks of conventional cameras are that you have to choose
> between getting a lot of light to the sensor (i.e. larger aperture), which
> results in a limited depth of field. Only a small depth range is sharp, the
> rest is blurry.
> >
> > Here comes the advantage of the plenoptic camera: It doesn't have
> mechanical parts, hence it doesn't need time to focus. Since it is a plenoptic
> camera, you can fix the focus depth later. In addition, you can pick an
> aperture so that you get a more bright image, with less noise, at shorter
> exposure times than a conventional camera.
> >
> > The real advantage of the lytro camera lies in the fact that you can
> take images with a stong depth progression in a snap, without thinking about
> which point to focus on.
> >
> > Take a look at the gallery: All images have structures from close to the
> camera to far away. This is what the camera probably does best. Think of
> the situation, when you try to take a photo of the kung-fu guy with the
> spear. With a conventional camera, you press the shutter and the camera
> focuses. Somehow it focuses on the guy, instead of the spear directly in front of
> you as you wanted. With the Lytro, you would take the same photo, but could
> later shift the focus back to the top of the spear. Try it in the gallery
> to see what I mean.
> >
> > In blender, we usually do this with the defocus node. As it is fully
> animated, you can shift the focus depth around. If you want an infinite depth
> of field, simply render without a defocus node.
> >
> > If you want to be compatible with Lytro's tools, you would have to
> render a light field compatible to the file format. Although possible (there is
> an extension for it) I would see that as a research tool only. The strength
> of a plenoptic camera lies in the fact that it can generate images that
> are sharp regardless the distance to the object, something that is not that
> easy with a conventional camera but very simple with blender.
> >
> > To quote the reply from kalast: What uses do you have in mind?
> >
> > --
> > Dr. Lars Krueger
> >
> >
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-- 
Dr. Lars Krueger


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