How to add destruction to a 3D scene part 1: building a city pre-flood

Introduction

For this project I’ll be showing the before and after of an apocalyptic scenario across three locations: city, suburban town, and a rural setting. I had to come up with different kinds of apocalyptic events to showcase each piece. This was a challenge just to get started because you’re not just thinking about how this shot will look, but when you’re setting up the before, you’re having to also factor in how the other after shot will look. So you’re kind of composing two shots simultaneously. It’s also hard to figure out which apocalypse event will be best for each location and making sure to give each its own unique demise!

I listed out each setting and noted the kinds of changes we’d want to see in the after shot. I began working on the city first and for this scene I chose a cataclysmic flood. It was important to know this when setting up my before shot because it would preclude certain camera angles, namely any shots looking up (because we wouldn’t be able to appreciate how flooded the location would be if we can’t see the water!). That’s an example of how careful I had to be when thinking of two images in one. With that in mind, let’s get started on my typical first steps.

Research

This is a real-world city scene and so the burden of research was less than if it were a fictional or period scene. But once I know the kind of scene I want to make, I will spend a lot of time looking at other pieces of art that I feel are successful within this theme. It’s important to know what art already exists so you can work towards that standard. While a city scene can be fairly easy to imagine, what’s harder to imagine is a city scene with good cinematography. I gathered about a dozen such pics from my favorite artists and put them in my usual PureRef window (PureRef, for those who don’t know, is a great free tool for organizing your reference images). These images served as a quality bar so I could set my sights high enough but also to help stimulate ideas. I might glance over and get reminded to try a certain angle or lighting set up.

To keep getting better at your craft, you have to know the art that’s already been done to a high standard, and aim towards it. You’ll never ‘arrive’, so this step will likely never get skipped!

Resource gathering

I almost always use 3D software to create concept art/illustrations, and when you’re making a very complex busy scene in 3D, you pretty much have to source models. You can’t just be building cars and a dozen buildings and characters and props or it’ll take you a month to create a single image. Once I’ve done my art research and I know roughly the direction I’m taking, I’ll start pouring through every resource I can to find free or cheap models. It’s surprising what you can find that’s either free or close to it.

For this scene I mainly used three sources for models: Sketchfab, Turbosquid, and Kitbash3d. Seeing as this is a tutorial about turning a scene from pre to post apocalypse, I didn’t want to make it about modeling but rather about lighting, composition, and the fine Photoshop elements necessary to take the 3D to the next level of believability. With Turbosquid you can sort by free/low price and with Sketchfab you can sort by downloadable. I actually got the majority of my building models from Kitbash3d when they were giving away free samples of their Cyberpunk Mini-kit. That mini-kit alone is enough to cater to much of your gritty urban city scenes. Other resources such as textures came from textures.com.

A digital artist’s bread and butter is their resource of models and textures. Make yours grow fatter every single month until one day you’ve got just about everything you need and your hard drive is bursting!

Getting started in Blender

Why did I choose Blender? Well, simply because the Kitbash3d models that I downloaded (when I downloaded them for free) were already in Blender format. But this particular tutorial is not software focused. In fact, I’d rather have chosen Cinema4D as Blender has some crazy quirks that I still haven’t overcome and it did slow me down. But one good thing was that in 2.83 it has de-noising, which shaves the render time by a fraction! Cycles is not quite as quick as Octane for quick real-time test renders, but in this scene (and just about any scene I make) I use heavy amounts of volumetrics. And that’s always going to slow things right down! Now, although this tutorial isn’t software-orientated, I believe it’s important to use something that can handle volumetrics well. It just adds depth and realism to your scene. With that in mind, I placed all my models into Blender and lit them with a HDRI from hdrihaven.com.

city landscape setting illustration planning
For many scenes, especially dense urban scenes, try to use software that handles volumetrics well.

Finding the shot

This is one of the hardest steps and took up the vast majority of the time I spent on this whole piece. Mainly because of how slow the render times are. Every tweak takes about 30 seconds to a minute to know whether it’s worked. During this stage I’m just trying to be open to possibilities and to try anything. As I said at the beginning, my main goal was to make sure I could get a nice shot with the ground plane visible. What’s key here is making sure the lighting is as close to perfect as I can get it. To that end, I’m making sure the light is hitting the buildings in such a way as to create a very simple read. I made a render to illustrate this point.

city landscape setting sunny day

Here there are no light blockers and the sun is just shining on all the buildings. As you can see it’s extremely chaotic to look at and this is why we have to control where our light lands by introducing large objects to block out all the light except for where we want to draw the viewer’s attention.

Final details in 3D

What I started to realize for this scene was that I wanted the before image to be busy and congested so that the after shot would be showing nature reclaiming the land and all the chaos of human activity would be gone. Once I’d found the final camera angle I began building up lots of gritty details and activity on the ground plane. As I mentioned earlier, I went to Sketchfab and looked through all the available free cars and various other models and started building up a sense of dirt, traffic, and pollution. Those cars are also going to help drive (no pun intended) the composition, so that we’re moving through the scene toward the focal point of the far buildings. I’ve also shown what the whole scene looks like in Blender.

city light blockers blender scenery

Note the big light blockers to help build the shadows.

Rendering system

This part is also time-consuming and often depends on how fast your render engine/computer combo is. Because I wanted to add motion blur to the cars in Photoshop, I had to render out what was behind them and then render them separately. I’ve found this is a good practice because often you really need your layers in Photoshop to reflect a natural order of far to near objects being separate. So I will render farground objects, midground objects and near objects separately so I can avoid painting on top of things that are under things… it gets complicated.

Now, in Blender 2.83, there’s still no way to render a traditional ID pass/puzzlemat. So to get clean alpha masks for your objects, you’ll have to hide all but the object you want to get the mask for, and render that in Workbench render mode and use flat shading to make it so the object is white on black. For this you’ll have to turn off your volumetrics so they don’t muddy the solid read. Here I’ve shown all my rendered elements.

photoshop organising adobe planning
Organising your render elements takes time but means you can relax a little in Photoshop.

Assembling in Photoshop

So when I get into Photoshop, I’m back into my comfort zone and can relax a little. No more rendering and crashes and Googling why such and such keeps disappearing when I do bla. I get right into assembling all those rendered layers, cutting them out using the black and white masks and essentially making the document make logical sense. Trust me, I’ve done jobs years ago where I didn’t do this step and my document was a total nightmare and really slowed down my process.

Once I’ve done that, I quickly throw in an initial sky, a basic contrast improvement (via an adjustment layer or two) and in this case a bit of fog (just a big soft round brush on low opacity) just to take out any sense of sterility or 3D-ness. This sky is actually my second sky pass where I’d spent some time working on it, but initially I’ll throw in anything that looks half decent just so I’m looking at something more photographic and less fake-looking. Now we have our base on which to build up the fine details. We’re going to be honing the composition with every step going forward.

lighting and shadows large city buildings
Make sure your Photoshop document is squeaky clean!

Detailing phase 1

At this stage it’s important to make the city come to life in terms of human activity so it can then be devoid of it later. Here I’ve added a few lights in some of the windows that might come on at this time of day as well as some gritty signage and a bit of smoke and smog. The city lights are just from night photography of cities where I’ll find a few good windows and paste them in using the color dodge blend mode. That near building needed a lot of work to look believable because it’s a fairly low poly model and is also fairly close to the camera. So I worked on just about every facet of that using texture overlays. It’s pretty important to do this when treating your 3d renders – work over the top with photo textures to remove the stiffness. Destroy hard edges and replace low detail areas with photography where possible. Notice how I did this with the upper windows in the near building too – just replaced them altogether. They were too simple and looked fake.

urban city life busy environment
Bringing the city to life.

Detailing phase 2

Now, it’s very much worth noting that to make this image work, while adding detail, we need to always be focusing on the composition. It’s no good adding details that distract and create visual noise. This was something that used to trip me up – why is it that when I add detail, it makes the piece more fussy? It would drive me crazy. You have to take measures to manage how these details read so that they don’t jump out and pull our attention here and there. After you learn this, you start to do it without being too conscious of it. In a scene with any type of atmosphere or simple lighting setup this is reasonably easy – you can just lightly airbrush over large contrast-y areas with a low opacity soft round brush. Try different values, not to  bright, not too dark, just right. This will knock back the darks and brights and make that area jump out less.

Compare the before and afters below with and then you’ll see how I knocked the contrast back with atmosphere.

busy city urban 3d landscape
smoke effects vfx city busy
busy environment design 3d modelling

These final details add one further level of realism. There’s cracks in the foreground pavement and some generic old metal texture for the long rectangular area in the foreground building which otherwise looks too simple. There’s also some smaller smoke elements to again reinforce life and suggest pollution.

One final thing I do with my paintings (along with my routine check for areas of distracting contrast) is to smudge away any hard edges that draw too much attention. It’s very subtle but every eliminated distraction from the focal point (in this case the tops of the far buildings and the cloud) helps your image to read well, and read is everything!

composition photography  real life 3d model
Never sacrifice your composition in the pursuit of detail.

Sketchfab Models Resources

  • Sabri Ayes
  • Reenafax
  • Sattak6
  • Bart
  • Smallpoly
  • Anathlyst

Read part 2 of this tutorial: How to add destruction to a 3D scene part 2 - after the flood

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