Monthly Archives: February 2014

[HDRI] Parking Lot

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While driving home today I got hit by a giant thunder storm. One of my main roads home along with the nearby parallel ones were flooded, and when the hail started getting bigger I found a parking lot to hide in for a while. It was actually owned by a car wash company, so they let me stay as long as I got a vacuum as well (which was long overdue anyway). While waiting for the storm to die down I grabbed my camera and tripod and took this opportunity for a nice HDR pano.

I’ve found that pretty scenery usually doesn’t make for nice image-based-lighting, so it’s better to keep an eye out for ordinary places that have interesting lighting – under a tree, next to a wall or inside a restaurant. When using these images for lighting, you don’t see the epic landscape reflected in your characters’s eyes, you see the soft diffuse glow of the sky, the warm bounce from the grass and the harsh rays of the sun. In other words, most outdoor IBLs give you the same lighting, especially when you have your own ground plane.

Making-Of 2.70 Release-Notes Volume Image

270vol05

Being an artist member of the Cycles module of Blender, every release I get to make pretty pictures to illustrate the new features in the release notes. This time was of course volumetrics.

For now, getting data from smoke simulations is not possible*, so the next most obvious demonstration are some epic light beams.

2014-02_33_c

Meh.

I tried a few things, but most of them were pretty abstract and could probably be done with only some compositing.

So in the end, I decided to make some kind of epic mountain complete with surreal god rays casting huge shadows over an ominous landscape.

Starting with some geometry generated by the one and only ANT Landscape addon, I added a displacement modifier using a Voronoi F2-F1 cloud texture to give it a bit of detail:

ml-1

The material for the terrain is fairly simple too – just some rock textures mixed together to get the colour and detail I want, and some normal+height mask to put some greenery on the plane below the mountain (though you can barely see this in the render)

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The world material is a simple Volume Scatter shader with a white colour, 0.4 density and 0.0 anisotropy. 0.4 for density is actually really high for the world shader, but I used an extremely bright light to punch through it.

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The light setup is where it gets interesting:

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It’s a single spot lamp really, but I wasn’t happy with the falloff from the edge of the light’s influence to the center, so I placed a semi-transparent plane in front of the light that allowed me to create exactly the falloff I want, and also to create an elliptical shape instead of the normal circular shape of spot lamps. This really allowed me to focus the light on a single point and create very dramatic shadows in the world volume itself. Without doing this, too much light was scattering in front and behind the mountain, making hard to notice that the mountain was casting a shadow at all.

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Finally, the light ray was pretty boring and quite obviously came from a plain spot lamp, so I added a noise texture to the plane in front of the lamp. This breaks it up and creates all those fancy rays of light instead of just one.

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The noise is pumped through that ramp just to give the light a bit of colour variance. I knew I was going to desaturate it heavily in the compositor later, but I still wanted some subtle variance.

A little bit of compositing later and we’re done :)

One thing I noticed was that volume rendering is surprisingly fast. Doing the final render only took about an hour on my 2600K 2.4GHz i7 cpu, which isn’t much slower than your average cycles render. Sure there’s only one light and it is an homogeneous volume, but I was really expecting much worse.

Great work from Brecht and the rest of the gang as usual :) One step closer to being a true production-ready renderer.

* Though I’ve yet to try this addon.

Equi-Angular Homogeneous Volume Sampling

equiangular

    This adds an option in the Volume Sampling panel, which helps rendering lamps inside or near volumes with less noise. It can also increase noise though and needs improvements to support MIS and heterogeneous volumes, but since it’s useful in some cases already (especially world volumes) it’s there now.
    Based on the code in the old branch by Stuart, with modifications by Thomas and Brecht.

-Brecht, commit

Thomas rendered the image above with just 10 samples! Cycles isn’t as slow as you thought ;)

Commonly Ignored Feature #12: #drivers

drivers

Here’s an interesting one. Drivers can be created quickly by typing the python expression directly in the slider of some value, preceded by a hash.

You’ve probably seen many folk typing #frame into the Seed property for cycles renders, but it’s capable of a whole lot more than that. The simple example above uses the same ‘frame’ property, but multiplied by 0.2 to make a slow rotation* of an Empty that the camera is parented to. Instant turntable!

Since it uses python, almost anything is possible. Using #bpy.data.objects[‘objectname’] would give you access to any properties an object or its data has.

One slight disadvantage is that these expressions are only evaluated during animation, not in realtime like your usual transformation drivers.

* If you’re observant, you might be confused as to why the the rotation value is so high. If 0.2 * 5 frames is just 1 degree, how come on frame 5 it’s already nearly 60 degrees and growing fast? This is simply because Blender stores and sets rotations in radians, and only displays the values in the more intuitive degree unit.

Commonly Ignored Feature #11: Hover Copy/Paste

hover-cp

 

Ok, so everyone probably already knows this one. Still, it’s almost as invaluable as Continuous Grab to me. When hovering the mouse over any value, colour or text field, just hit Ctrl+C to copy the value and then Ctrl+V when hovering over another field to paste it there.

One could argue about how Blender is missing all sorts of industry standard features like particle meshing and alembic cache support, but honestly these tiny usability features are what I love most about Blender (apart from the great community of course ;) ). Though that’s not to say I wouldn’t like to have particle meshing and alembic cache support ;)