Unreal Engine Part 14: Post effects

In chapter 14 of Rob Redman's comprehensive video introduction to Unreal Engine, learn how to apply cool and interesting post effects...

Previous tutorials

Part 1: Setting up a new project
Part 2: Introducing materials and landscapes
Part 3: Adding foliage and rocks
Part 4: Particle smoke
Part 5: Introducing the skybox
Part 6: Setting up cameras and post-effects
Part 7: Teleporters
Part 8: Adding random assets
Part 9: Destruction
Part 10: Adding sound
Part 11: Linking audio to actions and objects
Part 12: Using the matinee tool
Part 13: Lighting

When you are working on a non-interactive 3D project it's easy to get carried away, adding all manner of effects to your scene. Help details pop with ambient occlusion, sell your skin shaders with subsurface scattering. Ramp up the global illumination settings and have your lights bouncing thrugh your scenes. The reality is that you only need to render out once and you are done. In game engines this isn't possible but that hasn't stopped Epic introducing some neat tools to allow you to utilise some of those ideals to help you tell your story or set the scene.

In this instalment I'm going to show you a few items in the post effects system that will help you get the best quality visuals that will aid you in your storytelling. There are many post effects options but once you've used a couple you will be able to experiment with the rest very easily.

Step 01: Set the scene

It doesn't make too much difference which level you are working on here, as we aren't working on game mechanics or specific in game processes. The whole point is to add effects after everything else is done.

For my example I'm using a scene from the learn section of the loader. I've stripped out anything I didn't need but otherwise it's untouched.

Get your scene ready. Once you are happy with the gaming side of things we can move on.

Step 02: Pump up the volume

First of all we need to define an area for our post effects. Add one from the Volumes menu by dragging it directly into your main viewport. You will see a yellow wireframe cube. Resize this so it is a little larger than the area you want to affect. In this case I made it a little larger than the whole three room setup.
If you select the volume in the outliner you can then head to the details area and, under Post Process Volume, unfold the settings arrow, to reveal all the options we have available.

The yellow cube shows us the size and position of our post processing volume.

Step 03: In the grade

I'm looking to give my level a slightly more filmic look, so I need to make a few subtle (or not) changes to the colour and saturation. I unfolded the relevant areas and start by reducing the colour levels by around ten-percent. Once you're happy with your saturation you can move down the list and adjust contrast. If you are used to standard image editors you might be put off by the XYZ controls rather than RGB but it's really just a naming convention and it doesn't take long to get to the point where you don't think about it anymore.

Now I like to use the colour and saturation controls but you can do things differently if you wish. Further down the post settings you will find the film section, where you can do all kinds of things like adjusting contrast, adding a shoulder. If you are familiar with film grading you will find the settings here.

I had a slight Michael Bay moment here and went heavily teal and salmon with my tones.

Step 04: Blooming lovely

Sticking with the visual theme you may want to add some lens effects. Head down the list and open up the bloom section. You can have a number of different blooms but to keep it simple I stuck with just one. Reducing the threshold will increase the areas of bloom and the intensity is just that. This is recreating the look of highlights blowing out a little with some diffusion into closer areas of the frame, and can add a lovely feeling of airiness.

Open up the tint section to adjust the colour of the bloom. I went for a warm colour to match the highs in the scene.

Bloom can give the air in your level a richness that might otherwise be lacking.

Step 05: Focus

One thing that is more directly obvious when creating a filmic look is shallow depth of field and we have a post process for this too, so open it up to access the controls.

There are lots of options here but, using the circle method the most import are F-stop which controls the shallowness of the focal area, and Focal Distance which tells the camera how far away from the lens the focus should be.

If you combine this with some Motion Blur (settings in the image - really simple) you can guide the player through the level or control how much they see, which can make for a particularly immersive experience.

My settings for DoF here are quite extreme and in some cases that might be appropriate but usually you will want to increase the F-stop setting to something above 4.

Various lens blurring tools can be useful in not just the look but also guiding the player in their emotional response to the game.

Top tip: Watch films!

If you are looking for a specific look and are unsure how to achieve it then watch a film that has that look and pause often. Analyse what the colours look like and what is in focus and you will pick things up in no time.

Related links

Part 1: Setting up a new project
Part 2: Introducing materials and landscapes
Part 3: Adding foliage and rocks
Part 4: Particle smoke
Part 5: Introducing the skybox
Part 6: Setting up cameras and post-effects
Part 7: Teleporters
Part 8: Adding random assets
Part 9: Destruction
Part 10: Adding sound
Part 11: Linking audio to actions and objects
Part 12: Using the matinee tool
Part 13: Lighting
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