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Guide to Volumetric Shading in Blender 2.50

13

Here's a quick guide to the different settings for Blender 2.50's volumetric shader.

Stratus3D writes:

This is a html/pdf guide to all the parameters of Blender 2.50's volumetric shader. It contains images illustrating what every parameter does and explains the basic of how it works.

I have been working on this guide for several days and have rendered dozens and dozens of test renders. I have just posted it on Stratus3D.com. You can read it there and download the pdf. This guide is a work in progess and I will continue to update it as I learn more.

Link

About Author

Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.

13 Comments

  1. Matt, I have literally worked (in my spare time) for months on volumes and I still am not certain on various settings etc even with your documentation. Here's the thread:

    http://blenderartists.org/forum/showthread.php?t=166174

    It is my hope that one day a documentation writer will sit down and stream what's in your head into a good couple of chapters. the problem with trial and error is that volume renders take a while to render and you must spend a lot of time to really familiarize with what they do. I would love to see animations where the settings are animated and rendered so you can see in a video what changing various sliders do. PLEASE do not take this in any way other than helpful suggestions, I have nothing but gratitude for your and Farsthary's work, I am just remarking that the blender foundation could make a lot of money documenting what you've done (and they probably will). I for one will buy it.

  2. nrk: i'm more than happy to answer questions, though you know i can't monitor every forum that's out there. Documentation is a task that more than just coders can do and I'd love to see more people helping out here- like i said, happy to answer questions :)

  3. Nice, Thanks Stratus3D!
    Finally an interesting and the most useful kind of contribution!

    No need to waste time by watching a Youtube video style!

    Thank you again!

    Cheers

    /*** Mr BlenderGURU think about it! :p

  4. Thankyou very much!

    I agree with the other person who said it, this for every feature of Blender (While surely a huge task to perform) would be excellent, and teach a lot about how to use Blender.

  5. This resource is not helpful in a variety of circumstances, and it actually misleading in others. The official Blender documentation, mentioned by others, is much more accurate.

    First off, the model used is a sphere. While this may be good for surface material previews, it doesn't really do a lot for volume shading. The official documentation uses a complex, smoke like model to demonstrate the features. This gives a more accurate view of how the shading parameters would affect a real world model. Also, the official documentation shows what happens to shadows cast by the volume as the parameters are changed, which is very helpful for understanding how the volume will interact with the rest of the scene. Some of the images in the resource seem to have shadows cast by the volume (though it is really hard to tell), but if they exist they are always hard shadows, which is very unrealistic.

    Some of the comparisons don't make any sense. For example, when the step calculations are compared, one image has external shadows, and the other doesn't! Also, various lengths of constant steps are not compared. You need to show how a constant step and small step size reduce noise (but at the cost of rendertime).

    Finally, the Anisotropic Scattering section of this guide is just plain wrong. This value does not control how bright or dark (or flat or full) the volume is. This is very misleading. In order to see the difference between the various values of Asymmetry, you need to look either nearly directly from the light's perspective, or nearly opposite the volume away from it. If the value is positive, then the volume is going to look brighter when viewed opposite from the light source than it would from the sides or the light's perspective. The single view from the side incorrectly indicates that both positive and negative values have the same effect, and that that effect is similar to decreasing the scattering parameter.

    I would not recommend this resource to anyone actually attempting to understand volume shading. It presents only a partially accurate view of the parameters, probably because it tries to relate the volume shading to surface shaders. This is not a good idea. Many of the concepts that work just fine for surfaces have no meaning for volumes, and vice versa. If volumes are to be compared to anything, it should be sub-surface scattering, which is in itself an approximation of true volume rendering. In short, this document needs significant improvement if it should be considered a valid, accurate, and useful resource.

  6. Maybe you could make us a better one then Jason? ;P

    Optimally I would love a document that not only covers this but also shows where the buttons and controls are in the GUI, and how to get to them. Step by step instructions on how to create an object, apply the effects, as well as what each setting's effect is on the object. As well as a variety of 3D objects to see the render results. Such as a sphere, cube, smoke shaped object like Jason said, a character (like a human perhaps), a car, and maybe one or two others. Just to get a good feeling for how to do each of the effects, and what effect they have.

    And that for every feature in Blender would be just terrific! And would make Blender possibly the best documented piece of software every created. (I can dream can't I?)

    But, I won't complain about this as it is, because it does teach me something I didn't know, and the person who put it together has done a nice job of it. Even if it's not perfect, it's nice of the creator to give it a go. One more resource can't hurt.

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