Blender 2.43

February 26th, 2007 . 6 comments

I’m only about a week late, but I might as well do the customary ‘New version released!’ post, so here we go: Blender 2.43 is released! There, that’s better.

A challenge leading up to this release was getting the new website together. I’d pretty much finished the design last year, but it took a while for the admins to get the new server hardware ready, and for Bart to do the work integrating the templates with the CMS, Typo3.

The release provided as good an incentive as any to get the site ready, and thankfully this time with the new hardware, the website was pretty solid, despite it being thoroughly barraged by visitors via various news outlets around the web. There’s still a fair bit to do though, there are plenty of stale old pages in need of a refresh, and the forums and wiki design still needs to be integrated.



New Blender.org

As far as the release itself goes, here’s another little list of my favourite contributions this time around.

There’s one bit of disappointing news though. The next release was planned for a while to be a UI-centred Blender 2.5 release, for which Ton would do the huge and time consuming necessary internal upgrades that would allow features that I’ve been working on such as drag and drop in the outliner, a customisable toolbar, and radial menus to be implemented.

It seems now that once again, it has been decided for this work to be postponed in favour of a version 2.44 with smaller projects, meaning that it’s going to be at least May or June before any of these UI projects can be integrated. It’s a lot of difficult work for Ton to do, and it’s up to him to decide what he wants to work on, but it’s also frustrating and demotivating for me, because I’ve been waiting so long, being prevented from working on these sorts of improvements release after release. I offer my apologies to any of you who are waiting too.

Melbourne Graffiti Redux

February 14th, 2007 . 2 comments

Over the holiday break I spent a couple of days in Melbourne, and of course went on a graffiti spotting tour again to some of the excellent locations there. There are a few alleys that are pretty much outdoor art galleries, with art all over the walls that’s seemingly not only tolerated, but encouraged.

I’ve got the film back from processing and scanning now and uploaded to flickr. Interesting to see how things have changed from the last photos I took in 2005…



Artwork in Centre Pl

Unsharp Mask & Ambient Occlusion

February 8th, 2007 . 11 comments

A couple of days ago, I was experimenting with unsharp masks in Blender’s compositor when I came across an interesting paper by Thomas Luft, Carsten Colditz, and Oliver Deussen, Image Enhancement by Unsharp Masking the Depth Buffer. The paper describes a number of image manipulations that can be done by finding areas where there are sharp discontinuities in depth, one of which is quite useful as a way to fake an ambient occlusion effect in post.

Unsharp mask is a popular way of sharpening images, which generally gives much better results and flexibility than simple convolution filters. It may not be widely known, but it’s actually a wet darkroom technique, and is very easy to recreate with some simple blurring and blending. Unsharp mask finds areas of high local contrast by comparing the original image to a blurred version of itself, checks where it differs the most, then uses this mask to enhance constrast in those areas, usually in the luminance channel. The blur radius determines the size, or frequency of features that will be found.


This is quite simple to rig up in the compositor, below is an example with a deliberately grainy and blurry render to clearly show the effect of the unsharp mask.

Unsharp mask demo and node setup

Now that I’ve got an unsharp mask, it’s easy enough to follow through and look at implementing some of the techniques mentioned in the paper. One that interests me the most is where they use the depth buffer to give a kind of ‘drop shadow’ behind foreground objects, using the unsharp mask to find discontinuities and and mask foreground/background. This can be used like a fake, post-process ambient occlusion. With a low radius, it can be used to act like a dirt shader, darkening cracks and wrinkles, and with a higher radius it can act more subtly on larger features.

Below is an example of using this fake AO technique. I didn’t actually use this on the Waiting in the Basement image, but the model is a nice test case. I start by finding the creases and corners from the depth channel using the unsharp mask, then I do some tweaks to the intensity since what comes out of the unsharp mask isn’t immediately useful by itself, and doesn’t cover all the areas I want to darken. Because it’s using a non-antialiased Z buffer, I do some small blurring to the mask at the end to make it a bit smoother, and then use that mask to darken the image slightly, giving the detail shadows.

Note that I’m using the Min and Max options on the Map Value nodes to clamp the channel to between 0.0 and 1.0 before blurring. Since the channels are all float values, giving a range greater than 0-1 can make the blur nodes work in strange ways. The effect is much clearer on the full size image, especially around the collar and folds in the face, so click to check it out. Here’s the .blend file (2.43 RC+ required)

Fake AO by unsharp masking the depth channel

Waiting in the Basement

February 3rd, 2007 . 4 comments

I finished a new image today. I came upon this idea while sketching a week and a bit ago, and it was a good excuse to do some sculpting.



Waiting in the Basement

(click for full size)

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