Hard-surface sculpting
Zihao Zhu reveals some tips and tricks for hard-surface sculpting in Zbrush
Discover the essential techniques for sculpting hard surfaces in Zbrush
In this tutorial, I will be sharing the approach I usually take when creating a mechanical sci-fi character inside Zbrush. I will be focusing primarily on how to sculpt a clean hard surface efficiently, along with the essential tools you will need to know and some handy tips to make things easier. I will also share some of my thoughts on design in general.
From my understanding of design, there are several keys to creating a successful character. The first key is the silhouette. The silhouette can help the viewer recognise a character faster, even from far away, and a good silhouette can add characteristics and dynamics to a character. The second key is the rhythm. Rhythm exists everywhere; the line of action, the shapes, the colour scheme, and so on. Rhythm is a design language that has variety, yet is consistent. The complexity versus absence of detail, the dynamic nature of a pose, action versus still, and soft versus sharp are all rhythms that can appeal to the audience. The third key is anatomy. Every character should have proper anatomy, even a robot. I believe anatomy is basically how things are functioning in order for a character to move properly.
And last but not the least is the communication. There needs to be communication between the viewer and a character. A successful character should feel present. Gazes, expressions or poses are means to communicate with the audience.
01 gather references
When designing a character, it is important to gather enough references. In this piece, I got inspiration from Evangelion, W.A.S.P by Marco Plouffe, and Zetman. After gathering the images, make a collage and import it as a background in Zbrush, through the Texture menu. I am designing a humanoid robot like Evangelion, so keep the human anatomy in mind.
02 Blocking out
I personally like to put a general idea on paper before I sculpt, because it saves having to adjust things later. However, in this project, I am starting from scratch in Zbrush, which gives you quick feedback on how the overall shape and silhouette looks. In concept sculpting, I prefer starting from a sphere, with Dynamesh turned on, and then use brushes like Clay Build Up (my go-to volume build up) and Move (to move the polygons for adjusting silhouette and form).
03 find A rhythm
This is the stage to add general detail and develop your design. Find a rhythm of hard and soft edges, dynamic shapes (try to stay away from vertical and horizontal lines). For this piece, there are lots of curves on most of the hard surfaces. If you find there are too many curves in one area, use some sharp lines to break it up. This also applies to detail sculpting.
The brushes used here are Dam_standard (create general detail, and guidelines), Hpolish (suggest where the general hard and flat surface is), Trim Dynamic Brushes (clean hard edges, with Alt key to add volume), and never forget the Clay Build Up and Move brushes.
These special curve tools are extremely important for hard surface sculpting. They save you a tremendous amount of time, compared to the polish brushes. The Clip Curve tool will cut a mesh, Dynamesh might be required. Slice Curve creates two polygroups on each side of the slice with a perfectly clean polygroup border. Mask Curve creates a sharper mask.
At this stage, we need to break the modelling into parts. One essential ingredient to building a complex and realistic mecha robot is layers of mechanics. On the top layers we have the armour, and then there are layers of synthetic muscles, layers of wires, and other mechanics. And even on the top armour layers, we have armours
covering each other up. All of these layers will add shadows and Ambient Occlusion details, which will make your model more realistic.
06 sculpt the Armour
We will focus on the armour, since it is easier to sculpt other mechanics individually and use them as an Insertmultimesh brush. Begin by masking selections with the Mask tool and then polygroup them. Separate each polygroup into its own Subtool. Clean up the edges with the Slice Curve brush. Using Zremesh, clean up topology. Use the Panel Loop tool to add thickness. Crease the edge using Crease Polygroup Border and Zmodeler.
Make good use of Zremesh and poly-loop, as they will save you a lot of time later if you decide you want to retopo the model.
07 ADD crease lines to the Armour
After separating a piece into a Subtool, use the Slice Curve brush to create two polygroups. Use Zremesh with Polygroup turned on and Smooth Group Border set to 0. Use panel loop with Ignore Group turned on. Now crease and divide. Use the Polish By feature with the circle turned on to polish the two polygroups and crease the group border at the same time.
If the panel loop has Ignore Group turned off, it will create two separate mesh bases on the existing face’s polygroup. This can be used to create clean panel lines.
08 freehand sculpting
Using Dynamesh set to a higher value, extract a piece from the polygroup created in step 6. Clean the edge, Zremesh, and panel loop (with a higher Thickness to give room from sculpting), Dynamesh, and then sculpt however you feel comfortable. I like to use the Planer brush, because it is great for creating a perfectly flat surface, +Alt for filling in. The surface norm will depend on the surface norm of the very first polygon where your stroke starts.
The Planer Cut brush is also useful to cut in or elevate (+Alt). The Orb Brush Pack by Michael Vicente is fantastic for panel lines. Get it from https://gumroad.com/l/ nokhw.
09 ADD Detail
Detail can be added using alpha, and panel lines can use Dam_standard or using the panel loop option (see step 7). The alpha is purchased from Jonas Ronnegard. Clip Curve, Musk and Transpose can also be used to create details.
10 insert multimesh Brush
Let’s move on to other layers of mechanics. When building a robot, we need to think of how the robot can move. This robot primarily uses cylinder joints and hydraulic pistons. So I build those parts with separate tools, with the advantage of radius symmetry, and deforming options. Merge the Subtools and create a Multimesh brush (I made a pack of Multimesh brushes, available from https://gumroad.com/l/dqjr).
11 ADD variety
A good design needs a variety in shapes, forms and dynamics. It is better to add some ‘soft’ components like tubes, synthetic muscles, and fabrics. I will first create tubes or muscles using Curve tube brushes. Duplicate the Subtool, divide, inflate the tubes (to make sure that there are no gaps between the tubes), and then Dynamesh. Use Slice Curve to select an area where you want fabrics and panel loop it to get the thickness. We have a piece of mesh-warped around the tubes to sculpt.
12 pose the character
It is very important to refer to human anatomy. I use Transpose master. Pay attention to how the joints and hydraulics works.
I first pose the base mesh created in the concept sculpt stage, which is faster and safer to use than the Transpose tool. The entire detailed model is too heavy to use the Transpose tool. After you’ve finished posting the base mesh, I match each limb of the high-poly model to the base mesh one by one, and then pose the hydraulics, tubes, and muscles.