Greenhouse: Vegetation and Lighting Workflow in UE4

Goals of the Project

My main goal was simply to make vegetation to break out of my pattern of hard-surface while exploring more of Unreal. At DICE, I had worked in Frostbite for several years but since I joined Midwinter, it was all about Unreal and I wanted to get more comfortable in the engine as a whole.

With this in mind, I started thinking of environments that were somewhat easy to scale in size and a natural place for vegetation, which led to some serious googling of greenhouses and botanical gardens. 

We were already approaching the pretty depressing autumn period in Sweden (when the colorful leaves are gone but before there is any pretty snow in sight), so I was naturally drawn to images with sunny skies and lush vegetation.

I found a perfect greenhouse in the UK as the main inspiration for my scene. Even if it didn't end up being a 1 to 1 resemblance of that specific greenhouse, it was nice to have it as a reference for how they stack things, how the windows work, how the light behaves, etc. just to better sell the functionality of that environment.

The Blockout

The first part of the project was all about getting big brush strokes in place in blockout form (the building, the pots, the tables, etc.), get the idea of the lighting in place (the sun direction, an HDRI that contained the summer sun) while combining that with slowly figuring out how to construct the Hydrangea from scratch (since this part was completely new to me).

I continued building blockouts in sessions where I had limited time (usually weeknights), and as soon as I had several hours in a row to spare (usually weekends), I would dive in and focus on individual assets that require more brainpower.

For the second part of the project (when I started to feel that I had an understanding of how to actually build everything), I wrote down all individual assets on a paper and started to estimate how much time I had left on them before being able to call them done. This was mostly for me to get a grip of when I really could finish the project (I find it helpful to get this in black and white instead of leaving it at a gut feeling... even if the truth hurts). Luckily for me, it was around the same time when all Megascans content became available for Unreal users. So this meant that I could cross off things like buckets and shovels from my list while adding more plants without making my scope explode (Thank you, Quixel!).

The third part of the project was all about strengthening themes within the greenhouse (by prop dressing and adding a few well thought through assets like the awnings), getting the atmosphere in place (a shallow dive into cascade), getting the backdrop in place, color balance textures, etc.

Working with Megascans

So the absolute best part – according to my humble opinion – is the time you save on not having to build every single asset from scratch yourself when using Megascans. The service lets me focus on what I want to learn and build while letting me fill in the gaps with their assets. And I guess it is fair to say that this is the way you would work on any professional production as well. Any level, area or object that you make is usually part of a team effort.

The live link is what makes the experience with Megascans extra smooth when it comes to individual assets. You download an asset, click a button, and the asset is set up with shaders and LODs a couple of seconds later in Unreal. And if anything stands out in the terms of base color or roughness from your existing environment, you have everything ready to adjust that in a freshly created shader instance tied to that asset.

Tweaking the Assets

The vast majority of assets are either uniquely unwrapped with one UV set (like the pots) or using tiling textures (like the building itself) but I did set up a couple of things that diverted from these set-ups.

Ivy and Fern  
I needed to create my own meshes for the Ivy and Ferns (I had nice atlases from Megascans but needed to create the shapes), and I found it very helpful to use the curve to ribbon tool (Maya bonus tools). This gave a good mix of control and speed to create the shapes I needed. 

Tables
I started out just using a tiling texture from Megascans for the table but felt that I needed more variation and dirt on top of it, so I combined it with a dirt overlay that had a lower density but got me larger unique details for variety.

Concrete Floor

For the floor, I combined different materials that I created in Mixer. I wanted them to be based on each other but still provide variety. On top of this, I took a masked material straight from Megascans for the small rocks and then puddles in the end. I then used the vertex painting tool inside of Unreal to mask the different materials using RGBA. 

Production Tips

I worked with Patrick on Star Wars Battlefront a couple of years back, so I was really happy that he made this deep dive tutorial into vegetation after seeing his work at DICE.

For me, it was just very valuable to get a method for the entire workflow from start to finish. How to break down the entire plant into manageable details and how to rebuild it from the bottom up. It is like cooking. I had the ingredients but had no idea of how to make a dish out of it. But this gave me that.

I had kept several Hydrangeas on my balcony last summer, so I used them as a base for my in-game assets. The only thing I regret was that I took the photos at the very beginning of autumn, so the colors aren't as vibrant as they would have been in late spring. You can see some of the leaves starting to turn a tiny bit of red as well, so if I would do it all over again, I would try to time it differently. I should also add that I took the pictures of the separate leaves on a cloudy day on my kitchen table using my phone, so it was a very modest setup.

Working with Color and Materials

The truth is that it was a very iterative process. I think the white-painted greenhouse worked well as a canvas for the green/brown bounce light coming from the plants and pots. This gets lifted and enhanced by the warm HDRI and the warm yellow sunflower outside as a contrast to the cooler inside. To bind all of this together, I used a fog with a slight tint of yellow-green. Pretty late on in the project, I lower the roughness on most plants to make the entire interior appear moister as another contrast to the drier exterior.

But apart from that, it is so important to revisit your references and to get someone else to take a look at your work and give you feedback. Because you will get blind, and when you do, it is hard to put your finger on what is missing or what is off. A new set of eyes will help you out of that mode.

Background

I didn't have a clear vision for what to put in the background when I started the project. My first thought was that dirty windows combined with a blurred HDRI background would be moooore than enough for a background, but I soon realized that it wasn't doing the project a favor since so much of the depth got lost.

Instead, I started to accept the fact that the best approach would be to create a simple outside to mask the horizon. This is where I got lucky because Megascans had a pretty sunflower family that I could use as a soft wall outside of the greenhouse to cover the horizon and I found a perfect matching HDRI at HDRI Haven, which was taken next to a sunflower field.

I combined the sunflowers with a small patch of terrain, created a couple of terrain materials (that I got from Megascans), added some small and mid-scale scattering and used the HDRI as a visible sky.

Last but not least, I made some untextured fences just to get another silhouette going. And done!

Lighting

This is a static lighting setup with one stationary directional light and stationary skylight. I also added one point light at top of the Bonsai to give it a bit of a rim light boost where I used light channels to only make it affect the Bonsai.

All vegetation is set to movable and is lit by the Volumetric Lightmap but I added a static version of all the plants as well (that casts a hidden shadow) to get the green bounce light on the walls. In order to achieve a good result with the Volumetric Lightmap on an interior with relatively thin walls, I had to lower the cell size and be extra careful with the light mass importance volume. 

The glass in the roof is created by two layers of glass. One masked alpha layer (the completely opaque layer) and one translucent layer (semi-transparent layer). I also cheated and added a vague emissive to some of the windows to get a backlit appearance.

Time Spent on The Project

I started the project around six months ago but it's hard to say exactly how many hours I spent each week because the amount varied a lot from week to week. 

A rough estimate would be 5 – 10 hours each week. I think the most time-consuming assets were the Hydrangea and the Bonsai while nailing the overall lightning was another never-ending story when I was in the middle of it all.   

Jessica Helgesson, 3D Senior Artist

Interview conducted by Kirill Tokarev