Week 3 - Growing the foliage!
- Morgan Jones
- Feb 4, 2018
- 4 min read
Working out a suitable way of re-topping this tree was a huge challenge! I tried all of the automated methods I was aware of to even get a starting point but it was a very temperamental process because of the nature of this very complex volume. I decided in the end that I was being lazy and decided to take the best result that I had and manually edit the topology from there to get a good edge flow and level of detail in the Low Poly. This model came in around 50,000 triangles mostly because I wanted to get enough verts for an effective vertex paint in engine as well as the fact that it was a hero asset and needed really smooth edges that lit correctly in engine. This was a very experimental process from the get go, however I'm happy with the result.
The next step for this model was the unwrap. This was another tricky process because I had specifically put in an edge flow that I could unwrap to allow the Tiling textures to twist up the tree when flattened. If I had modelled the geometry straight up the tree I wouldn't be able to get the textures to line up, which was necessary for the design of the tree to get right. As you can see in the image below I tried to get the seams to the best of my ability to run up the twist of the tree so that I could line up the UV islands appropriately to the texture. The branches were much easier because I was just able to unwrap them separately, as you would a normal cylinder.
After I was satisfied with the unwrap, I separated the parts of the model that I had sculpted on to a different material ID in 3DS Max. The reason for this, is so that I can get all of my baked detail onto the necessary areas of the tree and then place tiling textures onto the rest of the model. I would then be able to use the 'blend angle corrected normals' node inside UE4 and the textures would blend together nicely. The images below show the quality of the sculpted bake onto the low poly model. I'm really thankful that this process was painless and worked first time, which is something that I never say when baking a model! Now that I am satisfied with how the bake came out, its time to get this model in engine and start working on making it look more alive, with some delightful foliage as it is a very prominent feature in the concept art.
Step one of creating the stylised leaves was to create some high poly models inside of 3DS Max. I wanted to keep the shapes nice and simple because they would have to read well from a distance. The texture was also going to be pretty low pixel resolution because of the visual real-estate the leaves individually take up in the scene is very minimal. I then created the stem with simple splines and baked all of this detail onto a low poly plane which would result as being the model that I use later on. I then edited the resulting alpha card to fit the shape of the leaves better and warped the model to give it more dimension.
The resulting images are of the base colour that I painted in Photoshop using the ambient occlusion and curvature as a base to work from as well as the resulting normal. Due to the nature of having these textures low resolution meant that I had to be very forgiving with detail and keep everything, especially the resulting alpha mask very clean. If I didn't do this, you would see very clear edges on the alpha as the stencilled shape bleeds onto the background leaving a nasty edge highlighting effect.
To finish off, I create a basic volume inside of 3DS Max that I would arrange my foliage around. This volume will also have a simple tiling leaf texture applied to it to allow for having fewer alpha cards, saving on unnecessary amounts of overdraw in engine. This mesh is still high density considering these factors, so imagine how much higher it would have to be without the volume to still get the same level of visual density in the canopy. When I was happy with the model, I sent it inside of UE4 to test the alphas and see what kinds of effects I could get with lighting and subsurface within the material editor. The result in engine can be seen below the crude max screen grab!
I'll talk more about what I did in engine to get these right next week when I've made some more finalised tweaks. I have also started messing around with my tiling bark texture on the tree which I feel is starting to really sell the level of detail that I am aiming to achieve in this scene. I started messing around with fiber-mesh today within Zbrush to try and get believable Spanish moss, which has been an ordeal in itself as it has already gone through at least 5 iterations to get to this point so I look forward to talking about this fun little detail. But as for now, I am definitely pleased with how this scene is coming on and Ill check back with you next week when I've experienced some more fun and challenging escapades on this scene!!
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