Cheese Board Material Study Process Document

Introduction:

My name is Kevin Kincaid. I am a graduate student at Savannah College of Art and Design, and studying Interactive Design and Game Development. This project was created for my Materials course, and has helped me improve my 3D modeling and material creation skills in many different ways.

For this project we were tasked with creating a scene in unreal to demonstrate our material creation and texturing ability. The task was to create at least six biological materials in Substance designer. The scene was going to be rendered twice, once in a normal version, and the second time after some form of biological damage had been inflicted on the objects. We had to create all the materials and models were were going to use. I think the final video I think is one of the best projects I've ever made:

Concept:

When initially choosing the project, I wanted to pick something that would have a variety of materials while being easy to model. After some consideration, I decided to go with a cheese board of assorted food. I felt it would be relatively simple to model, seeing as most of the items could be duplicated and adjusted slightly, and provide a wide assortment of textures for me to create. For the decayed version, I decided to show the food after having been left out for a period of time and subsequently becoming moldy and rotten.

Modeling:

The Modeling was done in Maya. This initial model used simple and geometric shapes. I created each individual food and then duplicated them to create the board.  In retrospect, some of the items were too simplified. In particular the apple slices and the brie cheese stand out as looking too precise and inorganic.

However, despite the problems with the model themselves, I was happy with the layout of the cheese board. I would keep a similar layout through this project. 

Additionally I was satisfied with the assortment of food. The ten foods are blueberries, grapes, apple slices, cheddar cheese cubes, brie cheese, salami, ham, crackers, jam, and honey.

The first draft used four materials: The inorganic, meat & apples, blueberries & grapes, and the remaining were on a single texture.

They had accurate texal density and were laid out correctly, but were too compact for the high quality render that was intended for this project.

Initial Material Creation:

After looking at cheese boards and individual ingredients for inspiration, I made a selection of ten foods to use in the project.  Each food has either one or two materials. The apple peel, brie rind, grape stem, and salami casing required an additional material to be created. 

As I was staring the material creation process, I worked on improvements for the model. In order to provide better resolution, I separated some of the items so that there were seven different materials on the object.

Process:

This class was my first real exposure to material creation. There were two projects before this, but those only used inorganic materials.  Still, I had a basic process.  I would work in greyscale to create the basic texture pattern, and adjust it as needed for the normal maps, ambient occlusion, and roughness. I also knew I needed  the materials to have user adjustable settings to assist me while working in substance painter.

Making the first organic materials after only working with inorganic textures was a bit challenging. I spent awhile experimenting with patterns in order to figure out how to make the objects look organic. There was a large amount of trial and error. 

Particular challenges were in trying to figure out how to make the surface of the jam and brie have correct height maps. 

After creating most of the materials, I exported them and painted the first draft in substance painter.

At this point several issues were clear. The meshes were were too geometric. Additionally, the food with two types of materials had harsh lines of separation. 

Materials wise, the crackers are also particularly clumsy. They looked decent in substance designer, but trying to apply it to the geometry had issues in painter. The apples and grapes also have very little visual interest. There was a lot of work still to do, and I wrote down as many improvements as I could think of.

However, the most crucial piece would be the addition of Subsurface Scattering, which we were just learning in class. 

Subsurface Scattering:

Mesh Improvements:

I began improving the geometry of the platter. This essentially amounted to rebuilding the whole model in the same layout. I worked to make several items smoother, in particular the apples and brie cheese, as well as curving the surface of the liquids. 

Subsurface Scattering:

I understood the concept of subsurface scattering, but it took me awhile to implement it correctly. The technical setup gave me some challenges. I had to continually return to my notes to confirm I had the correct settings. Even after overcoming that challenge, I would still take me a good amount of trial and error in order to correctly create the maps for SSS. 

However, learning about this technique made it clear what my materials had been lacking initially. I had been totally lost on how to create the shading effects on some objects, in particular on the cheese cubes. While figuring out subsurface shading, I made many other improvements to the materials. The jam in particular was a highlight. I added seeds and height, and the result was very visually appealing.  I switched inspiration on the crackers to a design that had less prominent holes. I think the first cracker design would only work if I changed the geometry of the object.

After making these improvements, I began painting the second version. I was still unsure about proper implementation of subsurface scattering, and only used a paint layer  rather than adding it to the materials I designer. After painting the model, we went a step further and imported the model and textures into unreal. 

The first set of materials in unreal turned out rather well, in fact it was much better than I expected. The background a was still a work in progress, but I felt everything was very visually appealing. However, there were a couple issues in both material design and mesh geometry.

Specifically, on the object there were a couple issues created with the displacement. The bowls would mess up when rendering from a specific angle, and the cheese cubes had some similar problems when the camera moved too close. Additionally, the honey did not have the look I was going for at all. I discussed these issues, and eventually came up with some solutions for the final version. 

I began to work on correcting the geometric issues, but first there was the challenge of aging the materials.

Rotten Version

Examination of Aging:

As established, the second version of this scene would show the food having decayed after being left out for some time. I began to examine the different ways that the decay would take place. I decided some of the materials, such as the cheese and salami, would become moldy, while the fruit would become rotten. The honey would crystallize, instead of decaying like the rest of the items. The amount of time that has passed in the scene is unspecified, as the rates of decay vary between items. Additionally, the brie rind would remain the same since it’s already mold.

Decay Creation Process:

I decided to design the materials so that there would be a single opacity slider to transition them between the normal and decayed versions. I would still adjust the input colors for the materials in substance painter, but the opacity slider took care of all changes to the normal, ambient occlusion, roughness and height maps. I first used this design in the previous class project, and it worked well.

For the most part each material falls into one of two categories: molding or Rotting. For the materials that would mold, I manipulated textures to create an image that resembled a single mold growth. I then fed the image into a tile generator and manipulated the results to blend with the clean versions of the maps. The parameters are exposed so I could adjust the mold patterns and colors in substance painter. The one exception to this process was the salami, which uses a single adjustable mold growth on the surface.

For rotting materials, I made use of height maps to deform the surfaces. The ham was the simplest, just warping outward slightly. For the fruit however, I designed the height maps to be used with a negative height multiplier. This allowed made the fruit to appear withered and shrunken. There is some slight complications with this technique. The grapes don’t use displacement in the clean version, so they’re simple, but the blueberries use displacement for the stem. As such those elements have to be accounted for when adjusting the mask to work on a negative multiplier.

The honey was still a work in progress at this stage, but the main changes would eventually be increasing opacity and applying displacement to the surface of the liquid. 

The material creation went rather smoothly. Once I figured out the node systems to create mold or rot, it was a matter of making simple variations on those systems for each material. . The initial version of the decayed scene is shown below. This still uses the same model as in the previous section, so some of the issues are still present. Additionally, not all of the materials had a dirty version when these images were taken.

Refinement & Improvements:

Modeling:

I once again returned to Maya to make adjustments to the model.

One thing I was learning through this project was in how to effectively make geometry that assists in material creation. For example, the previous version of the materials used displacement on the cheese cubes, which caused some rendering issues on the rounded corners of the cheese. I made the cheese cube edges more rounded in Maya, thus removing the need to use displacement map for the clean version. I also smoothed the transition between the brie materials brie, curved the cracker edges, and rebuilt the bowls to fix a hole. The last one actually created a different problem, because in recreating the bowls I somehow reduced the number of sides they had. This resulted in a very polygonal look that would need to be fixed later. The major geometric improvement I did was to the honey. I made the material cling to the edges of the container and added spheres to give the appearance of bubbles within the material.

The other changes I made were in editing the UV shells. This version increased the number of materials from seven to ten for greater detail. I also made edits to the UVs to help hide seams on the fruit and adjusted the wood board so that the planks would line up correctly.

Materials:

The majority of changes to the materials were simple. This stage was mostly focused on minor adjustments and changes. One larger thing I did was in adding subsurface maps directly to the materials in designer. I would still add to this effect when working in substance painter, but this gave me detailed surfaces that I would have been unable to create working in painter alone.

The largest material change was to the honey. After discussion with my teacher, it was decided the best way to adapt the honey was to treat it like colored glass. It took some experimentation with opacity and refraction index to get the effect correct.

At this stage, I also reorganized the materials to make them presentable. I deleted any unused nodes, straightened the graph connections, and added additional labeling to help demonstrate my process and the different sections. I also made sure the exposed parameters were well labeled.

Presentation:

The materials were transferred through the process to move them into unreal. This time, a full video of the entire process was rendered, which was the item that was turned in for the class assignment. I played around with camera angles, and did my best to give each material a good amount of focus in the rendered video. I was very satisfied with the submission, but there were still additional improvements that could be made.

Based on the feedback I received, I made a few changes to create this final version of the project. I adjusted the jam to prevent the seeds from creating overly impactful displacement on the surface. Additionally, I added height to the rotten ham to make it appear deformed and smoothed the surface of the bowls. The largest changes were to the grapes and the honey. I increased the roughness of the grapes and added additional subsurface shading to make them appear softer and squishy. They are quite reflective in the first version. I also finally achieved the intended appearance of the honey and created a much better crystallization effect on the surface.

Finished Materials & Renders:

Conclusions:

Overall, I am very happy with both the finished product and how my skills developed during this project. When I first conceived of this idea, I was unsure if I had the skills to create a project that would live up to the concept. This was a large undertaking, but it proved a wonderful learning experience. In addition to learning subsurface scattering and techniques for making biological materials, I think my greatest takeaway was in learning how to effectively model objects to be used with biological materials. Editing the cheese board was very time consuming, and if I had designed the objects differently in the first place, I would not have needed to make so many revisions to the mesh. I learned a lot about deciding whether aspects should be created through geometry or material design, and it will help me be more effective in the future. 

This class was my first real foray into making procedural materials, and I enjoyed it a lot. It is always a challenge to create materials that effectively imitate the references, and it takes a lot of trial and error. I am excited to continue developing my material creation skills and see what I will create in my next project.