Bench Grinder: Workflow Tips for Hard-Surface Prop Production

Bench Grinder: Workflow Tips for Hard-Surface Prop Production

Parth Naik shared plenty of details behind his 3D Bench Grinder: from texture padding and baking to working with a highpass filter in Substance Painter, setting up wear and tear, and presentation in Marmoset Toolbag.

Introduction

Hello, my name is Parth Naik I am a student originally from Mumbai, India, studying game art and simulation here in the US.

My first introduction to 3D was when I was in 8th grade. I had watched the movie Avatar and the environments in that movie had blown my mind, so I had decided to pursue the route of computer graphics. It was not until I played games like God of War and Uncharted that I realized I could work in the games industry. I used to watch the making-of videos and they got me really interested in the particular field of 3d modeling. After some research and browsing through ArtStation, I realized that the creation of props and environments was what I loved.

Currently, I am working on getting a degree and creating my portfolio to land a job in the games industry. I love prop creation and I would love to expand my horizons by entering the realm of environments. I know the pipelines are different and I have a lot more to learn.

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Bench Grinder: Goals

With the Bench Grinder project, I wanted to practice realistic prop creation and work on my modeling and texturing skills. I wanted to understand the construction of realistic props through the modeling process and the way materials react through the texturing process. I chose the bench grinder as it had some interesting wear and dirt collection and showed how the prop had gone through the ages of usage.

Reference Gathering

While I love to gather references by myself, some props or objects cannot be found close to where I live. In that case, the internet is the best place for reference gathering in my opinion. And for me, YouTube channels that show the restoration videos of various workshop tools are the best resources, as they provide zoom-ins and detailed breakdowns of the props. The zoom-ins help in the texturing process while the detailed breakdown helps to understand the anatomy and the mechanics of the prop which comes in handy in the modeling process.

Modeling

I follow the basic hard-surface modeling approach, i.e. I go from blocking out the model to high poly and then to low poly. While modeling the high poly, I try to stay true to how the model is made in real life; this helps me to maintain the right proportions so that the model remains true to its real-life counterpart.

While modeling from references, it is crucial to get the proportions right. It might be helpful to establish a unit of measurement in your ref that you could easily translate into your 3D software. This could be anything; for me, it is usually a nail or something that is small and simple, available abundantly in the refs, and can be easily translated in Maya.

For the low poly modeling, I try to retain details where they are absolutely required – these are mostly areas that affect the silhouette of the model.
At the same time, if I can get away by reducing the amount of geo used, I will go ahead and do that. For example, in this case of the screw, I was able to bake the detail onto one segment in the LP.
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UV Mapping

While I was aiming for a realistic look for the prop, I wanted to keep it optimized for games, thus I went with the approach of mirroring/stacking to maximize the texel density on the various parts of the grinder. I also decided on using a single texture sheet for laying out my UVs. The way I approach UV mapping is easy: I try to layout the UVs using the layout tool in Maya’s UV tool kit while keeping the given settings.

Note that these are not the ideal settings but the settings I use to get the results. I try to keep the pixel padding in order to ensure cleaner bakes. The padding also helps to ensure there is no bleeding when the textures are mipped to lower resolutions. The concept of pixel padding is crucial in order to understand how textures work in a game engine. This topic is explained in a super informative way in one of the tutorials by malcolm341 you can find below. His tutorials provide explanations of the various concepts in 3D, especially concepts related to game art. 

Another guide to texture padding can be found in this polycount thread.

Once the islands are laid out with the tool, I try to move islands a little to get a better TD. Once I’m happy with the packing of UV islands I move on to baking.

Baking

While baking the HP onto the LP, I try to reach the result as clean as I can. To make sure the bakes are clean, I follow a single rule: introduce UV splits wherever there are smoothing splits or hard edges. This is done to ensure that the gradient brought by the smoothing group split has enough blending space.

This could be easily explained with an example. Consider two cubes: one having UV splits on smoothing splits (A) and the other with no UV splits on smoothing splits (B).

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When an HP model is baked onto cube A the result causes artifacts on the edges. This happens due to the absence of a UV split when there is a smoothing split.

When an HP model is baked onto cube B the result causes no artifacts on the edges.

This concept is explained in detail in this polycount thread.

Once I am happy with the baked result, I move on to the texturing part.

Texturing

When it comes to texturing, the first thing I do is go back to the ref and analyze the ref to see what materials the prop is made of. In the case of the grinder, I distinguished metal, paint, and plastic. The main body of the grinder is made up of metal covered with paint, so in order to stay as close to the source material as possible, I decided to make a base metal layer, cover it with grime to show how the metal has aged, and then add a coat of paint. A trick that I have learned from getting feedback and critiques is that the materials should look interesting on the most basic geometry, i.e. if your material looks interesting on a shader ball then you have a strong base to work from. Like I mentioned above, the grinder had two base materials, the metal and the paint, and they had to be authored separately. Once I was happy with both, I combined them using a black mask giving that peeled paint look.

For the peeled paint, I followed a tutorial by Stanislav Teslenko (see below). In that tutorial, he talked about how one can use a highpass filter in Substance Painter to get fake shadowing under the paint chips thus giving them a false sense of height. This effect can be used in making stickers and decals floating on the mesh.

Once the base materials for the grinder were done, I moved on to adding some details of wear and tear. This is the most exciting part for me as it takes the prop from a general bench grinder to a specific grinder. This is where one can think about the storytelling aspect and how the prop reflects that. I first start by putting all the decals like stickers and signs in their places. For the decals, I get the images from the web and alter them in Photoshop to get the result I want. Then, I import them into Painter and I add a black mask to get a worn look. After that, I add a layer of dirt and wear, and finally, the fake shadowing effect using the highpass filter tutorial which helps me ground the decals further.
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Once all the decals are in place, I start working on that wear and tear on the prop. This includes a layer of dirt and dust accumulated due to the grinder not being used for several years, smudge and oil stains on the plastic, and various other things. In my opinion, this is the process every artist should spend their time on as it adds some character to the prop. One handy tip that I got from watching Chun Chun Yang’s texturing tutorials is that one can extract alpha masks from the refs or at least interpret them to get closer to the reference. Here is a tutorial in which she talks about how one can extract alpha masks to use them on textures:

Even though I use different software (Substance), the concept remains the same.

Lighting and Presentation

Lighting and presentation, in my opinion, are the make-or-break stage. I know everyone is exhausted by the time they reach this step in the process, but this is where you need to push yourself in order to set up a presentation equal to the quality of your prop. And lighting makes all the difference.

Here is a render of the grinder with a flat lighting:

And here is a render of the grinder with a more thought-out lighting setup: 
For the lighting setup, I try to start with 3-point lighting as a base and then move from there. I tend to add more lights than just those three to get the look I want and concentrate more on the variation the light produces on the prop rather than worrying about the number of sources. The image below explains the process a little better.
One important thing to keep in mind while you are lighting in Marmoset is to increase the width of your lights to achieve softer shadows.
I try to play with the camera settings, especially the FOVs and stuff, to get varied looks. I also encourage people to play with the render settings to get the desired result.
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Once I am happy with the lighting, I go ahead and take shots for my posts. One problem I had with Marmoset renders was the banding that I got when the background had a gradient. This banding problem can be easily overcome by taking the image into Photoshop. There, I first mask out the prop to separate it from the background. When I have the background on an individual layer, I add a noise filter and after that, a surface blur filter. That does the job and takes away the banding resulting in a cleaner backdrop.

When I am happy with the screenshots, I move on to exploring different angles for my thumbnail. This is the one I ended up with for the bench grinder post:

Parth Naik, 3D Artist

Interview conducted by Arti Sergeev

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