[Bf-committers] A new photo format

Shaul Kedem shaul.kedem at gmail.com
Thu Jun 23 16:33:16 CEST 2011


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

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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