Studio@jumpers-inn.de

Played a bit with physics simulation in Blender and rendered the image with Luxrender. Fun stuff!

Falling chairs!

Raytracing techniques are making rapid progress enabling almost realtime raytracing. Check out this demo of VRay RT:

This is all cool, but VRay is a commercial software that officially only supports 3DS Max and Maya, costs quite a bit, so nothing a true Blenderhead is excited about. But the good news is that the open source community is already on it! SmallLuxGPU is the project you’ll want to have an eye on:

SmallLuxGPU v1.5 (OpenCL) from David Bucciarelli on Vimeo.

The more I play around with Lux render, the more I like it. Two main reasons for that: first, you can fairly easily achieve convincing result because of the good material presets it brings along, second, it’s got super nice network rendering capabilities.

So in this post I want to show you the newest project I’ve been doing using Lux render. While browsing the web looking for inspiration for photography (see last post) I stumbled upon this image by Derek Cooper:

Inspirational image by Derek Cooper

This is a rather simple scene consisting only of the bottle, the glass, a flat table and a background. Even though content-wise it is simple, the lighting and slight depth of field effect make it a challenging subject for photography and more so for rendering. But that also makes it a perfect practice subject for playing around with a raytracer like lux. Modeling effort required is rather low and so you can pretty soon concentrate on getting the light and dof right.

Scene setup in Blender

Modeling this scene in Blender is very easy. I just used the image as a background image, traced the outline of the bottle and the glass with a polygon and then spin duplicated it from the top view to get a complete mesh. After that I cut off the top of the bottle (the blue part), as this would get a different material. I also added a subdivision modifier to each object to get it nice and smooth. The label of the bottle is an extra mesh that I bent using a shrinkwrap modifier onto the bottle. The glass is pretty much the same, I cut off the filled part and made it a unique mesh with the same material as the main part of the bottle. The table is just a plane textured with some wood texture. The background is a L-shaped mesh with an added subdivision modifier to make it like the typical background piece of table top photography. I then added two light sources and that’s about it (compare the setup shot below and download the .blend file at the end of the article). Next thing is the material setup in lux.

I set up the materials as follows:

• Bottle (main part): Rough glass with slightly yellow transitional
• Bottle (top): Matte blue (should probably be a tiny bit glossy)
• Glass (filled part): same as bottle main
• Glass (unfilled part): Glass (standard)
• Table: Matte with wood texture
• Background: Matte, grey

The result of this can be seen below. I set the output resolution to 1024×768 then cropped the final image. As lux keeps improving the image as long as you let it a good result can take quite some time. I used four machines in total, my laptop and three remote machines to render this in network mode. Total render time is approx. 16 hours. As you can see the render does not totally match the original image in lighting and materials. I find it pretty hard to adjust the lighting with lux as it takes quite a lot of time to see the first results. I guess this needs more experience. The different materials also would need more tweaking, especially a liquid filled glass bottle probably needs a different approach. Next time I’ll try to model the liquid as a separate mesh and see if this looks better. Maybe one can also get away with a more sophisticated glass material. Anyway it was fun and these kinds of scenes are great training for getting to know lux!

Final image rendered with Lux render

Download the Blender file here: Lux render example scene -

Note: textures are not included in the .blend file. The file is provided under a Creativ Commons License

Lux render test von Alexander Kasper steht unter einer Creative Commons Namensnennung-Keine kommerzielle Nutzung 3.0 Deutschland Lizenz.
Beruht auf einem Inhalt unter www.derekcooper.com.
Über diese Lizenz hinausgehende Erlaubnisse können Sie unter http://studio.jumpers-inn.de erhalten.

As you probably know, there’s quite a lot of raytracers out there that have exporters for Blender. Some time ago I tested Yafaray as an alternative to the Blender internal raytracer. Results were pretty good, especially for architectural scenes this is a really good raytracer.

Recently I stumbled upon Lux Render, which claims to be a physically correct raytracing solution. It’s also open source so definitely worth checking out. The gallery on their homepage surely is impressive so it was time to test how its usability is for a hobbyist like me. Installation is straight forward (at least in Windows) and there’s a nice export script for Blender. One thing I immediately liked about Lux Render is the documentation. There’s a whole lot of it which is pretty up to date and gets you easily going. If you’re using Blender just check out the “First scene tutorial” and you’ll have a sweet render in no time.

Render results are good, but as always one needs to get used to the specific interpretation of light values and other stuff. There’s also another thing I found rather odd: when rendering there’s no progress bar or anything to give a hint about when the render is finished. Why is that? Short answer: the render is done when you think it’s done. Lux render iteratively renders images, improving the quality in each iteration. You can follow this progress in the render gui and in the first few iterations the improvments are quite noticable. After a while though there hardly seems to change anything. This is irritating first, but has the advantage that preview and final image only depend on how long the raytracer is allowed to render.

Here’s my first (and so far only) test with Lux render, way to go to the level of their gallery images

Simple lux render test