Experiments with Blender 2.8, Eevee and how it compares to Cycles in 2.79.

[Jim Craig]

Hey, folks, 

I've finally figured out how to automate the 5-camera set up in Eevee and done some comparisons with Cycles running in Blender 2.79.

Here are some of my findings (which are not promising):

For simple scenes, there isn't appreciable time savings with Eevee. In fact, it can take longer to render scenes than it does in Cycles. Each image renders faster in Eevee (in my example, 2.19 seconds per image as compared to 6.25 in Cycles) but you have to render five images for each frame of the final animation so this offsets the speed. 

The setup is more cumbersome. In Cycles, I set up a single fisheye camera, set up one output file and render from that. To automate the rendering with Eevee, I need to create five cameras, bind those to an empty that handles the pan/tilt of the rig then bind that to an empty that acts as a dolly for the rig. Then, only after I've made sure that everything is exactly how I need it for the final render, I have to make 4 identical duplicates of the scene, select which is the active camera to render that image then set the five output files. If I need to make a change, I need to delete those copies and do that setup again.

Once I've set up the scene, I have to exit Blender, open a terminal window (a command line interface for the Windows users out there) and type in a fairly long but easy to follow string that executes the program and renders all the scenes to their correct directories. The automation doesn't work from the GUI. It has to be executed from a command line.

After that has finished, I have to stitch the images together to make a dome master. I can do this in Blender using Cycles and that's actually fairly quick.

There are also some things that Eevee doesn't do well, chief among them being how it handles shadows. Eevee isn't a ray tracing rendering engine but a raster rendering engine which is more like the kind used in video games. Shadows are approximated then baked onto the scene. I tried using a transparency map to create the rings of Saturn and while the rings themselves looked pretty good, the shadows they cast on the planet weren't even remotely acceptable. 

The biggest advantage I've found to using 2.8 is that it still supports Cycles and, unlike its predecessor, it allows you to use the GPU and the CPU together in Cycles. This means slightly faster rendering times and fewer "CUDA out of memory" errors because it uses your computer's main memory and not just the memory on your graphics card.

The latest version that I've downloaded, 2.80.37, supports the panoramic equidistant fisheye camera so it's still quite usable for dome video production.

Here are the times for a very simple scene that included a mapped environment, two primary objects (a moon and the LEM) and a single light source set as a sun lamp.

Eevee render time - 56 minutes, 42 seconds

Eevee conversion time - 6 minutes, 44 seconds

Total - 1 hour, 3 minutes, 26 seconds

Please note that this doesn't include setup for the camera rig.

Cycles render time - 31 minutes, 49 seconds

The results speak for themselves.

If you get a file that was created in Eevee, it's not possible to get it to render correctly in Cycles, even in 2.8 because there are so many differences in the way these to rendering engines handle light sources. So if you receive a file like this and want to render it as an all-sky image or animation.

If anyone is interested in that, let me know and I'll continue with the rather lengthy tutorial I've been creating.

Jim Craig

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[Jim Craig]

I did a somewhat more complex scene and saw how vast the difference between Cycles and Eevee can be. It's a dumb scene but it was for testing purposes so I didn't expect too much. :)

Here are frames side by side with the comparisons. 

As you can see, Cycles took much longer but made a more realistic image. 

So whether or not you use Eevee will depend entirely upon what you're trying to do.

This said, I'm no expert in using Eevee but plan to experiment further to see what kind of results I can get.

JC

[Jim Craig]

Open the image in a new tab if you want to see it full sized. 

JC

[Ken Murphy]

Thanks, Jim, for doing all this investigative work.  I hope you continue to work on your tutorial.  It's nice to have options when trying to create scenes with just the right look and quality.  I'm beginning to see that I will likely do most of my fisheye work in Cycles but at times turn to Eevee to produce scenes when going for a particular effect.  I'm teaching a Blender class on my campus and the students seem to really like 2.8/Eevee (mostly for flat viewing).  We will be completing our first complete animations tonight and viewing them after spring break as a class.  Keep up the good work!

Ken