[Pano] Golden Gate

GoldenGate_600p

 

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Turns out pretty scenery does actually make for nice image-based-lighting ;)

I went on holiday with my family last weekend to the Golden Gate Highlands National Park, just North of Lesotho and down the road from Bethlehem (not that one).

I took a crapload of photos that I’ll upload sometime, surprisingly even more than I did when I went to see Rex in Scotland for three weeks (which I suppose I never mentioned here), but that’s probably because many of them were sets of different exposures as well as two (HDR) timelapses and two of these HDR panos (yes, another one coming in a few days :) )

 

And Then There Was Cake (WIP)

conciliate_02_HR

 

conciliate_02_screenshot

Last weekend’s challenge on BA was themed Conciliate - which is basically the root word for reconcile - and means to stop someone being angry, or make them a friend.

I had something a bit more ambitious in mind, but I worked all day Saturday and Sunday and could only get this far. So, I’ll continue this later when I have some more time!

This is actually the second time I’ve modeled a Companion Cube… no idea what happened to the other one, but it probably had crap topology anyway :P I’ll upload this one (and the cake) to blendswap sometime soon.

World Volume Tests

Most of you have probably downloaded the 2.70 RC by now and probably started playing around with volumetrics in cycles. Immediately you probably noticed how slow it renders, although that was probably expected. Here are the results of a little test I did to find out exactly how to speed up volume rendering for the world up so that it’s actually usable.

The very first and foremost thing you need to know about volumetrics is the difference between Homogeneous and Heterogeneous volumes. Basically, a volume where the density is driven by some texture is a heterogeneous one, and a volume with consistent density is a homogeneous one. The difference in render time and quality is… well, quite drastic:

Homogeneous vs Heterogeneous

Homogeneous (2m 40s, 512 samples) vs Heterogeneous (1h 4m 55s, 128 samples)

Yep, you read that right. Under 3 minutes for homogeneous volume and over an hour for a quarter of the samples in the heterogeneous volume. The heterogeneous render seems to have a less dense volume, and I guess it does since it was driven by a noise texture where I couldn’t easily control the density and honestly couldn’t be bothered to wait long enough to give it a decent try.

Strangely enough, homogeneous is off by default – so make sure you change it:

homo

In all the next examples the volumes are homogeneous, rendered at 512×512 with 512 samples (a coincidence) and use the Path Tracing integrator

The next thing to note is the difference between a mesh light and regular lamps:

01_mesh_vs_point

Mesh with Emission shader (1m 15s) vs Point Lamp (1m 8s)

Not only do regular lamps produce a much cleaner render, but they also respect the Homogeneous Sampling method in the render settings:

Distance vs Equi-angular

Distance vs Equi-angular

samp

View the renders full size and you’ll notice that the Equi-angular mode is much cleaner in general, but especially closer to the light source. The render times were basically the same, 1m 8s for the Distance mode, and 1m 19s for Equi-angular. One thing I noticed though is that volumes in regular materials (not the world) render much cleaner using the Distance mode, the other way around, and sometimes spot lights are more noisy with an equi-angular world volume – so you’ll just have to try both.

By default, volume bounces are set to 1. This is a decent trade-off between render times and accuracy, but if you want to accentuate the light rays or give the scene a bit more contrast, reducing the volume bounces to 0 will speed it up quite a bit. Then naturally, increasing the bounces slows it down a lot:

03_bounces

0 bounces (1m 19s), 1 bounce (2m 26s), 2 bounces (3m 26s), 10 bounces (9m 22s)
Bounces and rendertime scale linearly it seems

No only do more bounces mean a slower render, but a noiser one as well. If you want an image that lacks contrast like the 10 bounce render, I’d suggest using only one bounce and just adding a large fill-light behind the camera. Or just reducing the contrast in comp.

Finally, you’ll have noticed the abundance of fireflies in the renders with more than 0 volume bounces. To cure this, we simply need to call our old friend the Clamp property:

04_noclamp_vs_5clamp

2.70 now has separate clamp options for direct and indirect light, so we can preserve the brightness of the highlights and still reduce fireflies by clamping only the indirect rays (rays that bounced off something and then light something else). Here the Indirect clamp was set to 5, and only increased the 3m 26s render by another 10 seconds.

Hope this saves you some frustration! But still go and do your own testing as well, you’ll probably learn a whole lot more, and then share it with the rest of us!

I’m particularly curious about making some procedural mist or fog with variable density, but still rendering it efficiently somehow.

 

PS: Heterogeneous is a funny word I hope I never have to spell so many times again.

[Pano] Parking Lot

parkinglot_600p

 

render

 

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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)

ml-2

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.

ml-4

The light setup is where it gets interesting:

ml-3

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.

ml-5

ml-7

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.

ml-6

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 ;)