In this tutorial I will teach you how to use the Quad Draw tool found in Maya 2015 to create a low-resolution mesh out of your high-resolution sculpture created in ZBrush, Mudbox or whatever sculpting program you prefer, and keep it usable in your game or film project.
Sculpting is amazing and it is one of my favourite parts of the character-creation process. It feels great to have a super-highly detailed 3D character that has pores, wrinkles, tiny textures on cloth and every other surface. However, if it doesn’t run in your game or your chosen animation software, it’s basically useless.
We have to lower the resolution while keeping the right edge flow so that the mesh deforms correctly during animation. This is why you will need to have a solid understanding of what a good model looks like in wireframe. If you haven’t created a low-resolution model before, it’s important that you research correct mesh topology as they are used in the games or film industry.
As a teacher, I often see my students type topology into Google Images and use the first image that pops up as their reference. This is lazy and it’s bad practice. There are too many bad examples out there. If you’re looking for reference, go after the stuff that is created by professionals.
This part of the character-creation pipeline is called retopology and it is extremely important to get it right. In many cases this will be the final mesh that you will use for the rest of the character’s life.
Something to remember when creating topology is that when modelling a real-time mesh, it’s absolutely fine to have tris, but remember that every edge has to be there for a reason. Proper edge loops are crucial and should always adhere to the high-resolution model’s silhouette.
If this is your first attempt, realise that you will make mistakes. If you do, don’t stress. Making mistakes is all a part of the learning process and they have to be made so we can learn from them. If there is a part of the mesh that isn’t working properly, just delete that section and start again – it’s a lot easier than trying to fix bad edge flow! Like sculpting, regular practice and repetition goes a long way.
The character featured in this tutorial is fan art based on a character from Carbine Studio’s game, Wild Star.
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Step 01 – Export from ZBrush
Once you have your high-resolution mesh completed in ZBrush, it’s time to reduce its polycount before exporting to Maya, as on most machines a 10-million tri mesh will not successfully run.
Merge SubTools that you want to keep grouped together in Export, as this will make the retopology process much easier. Go to Zplugs>Decimation Master>Pre-process All. Once the pre-processing is done, go to Zplugs>Decimation Master>Decimate All. Your model is now at 20 per cent of the original polycount. Now export your model from ZBrush and import to Maya and put each grouped high-poly piece on its own separate display layer.
Step 02 – Plan and use reference
Before you attempt retopology on your model, make sure you gather reference. A good place to start is the 3D Artist gallery, or Polycount’s wiki page. There is a section devoted to topology if you follow the links in the Character section. Make sure you have a whole bunch of reference for the different parts of the character and from different angles. Another good idea is to get a screenshot of your sculpt and draw over it in Photoshop, trying to make a plan for your retopology before you even open Maya.
Step 03 – Make live and start to quad draw
It’s time to retopologise! Make sure your high-poly model is on its own display layer. This is so that you can hide parts that you aren’t working on at any particular time. Select your high-res model and make it live by using the magnet symbol at the top of your screen, or go to Modify>Make Live. This enables you to create polys on top of your sculpt. The verts will also stick to the mesh, which will help you to keep the same silhouette. The tool you will be using is the Quad Draw tool.
Step 04 – Retopology time
Activate the Quad Draw tool. As long as you have made your high-poly model live, you will be able to add points to the surface and turn them into polygons. If you click on the surface, a green dot will appear. You can move them around by using middle-click. Create four points, hold Shift and hover your mouse cursor in-between the four points, then click. This is your first poly! Now you can create two green dots near an existing edge. Quad Draw will recognise the existing verts and you can create another polygon.
Step 05 – Learn the shortcuts
Learn the keyboard shortcuts for Quad Draw, as if you don’t, you will be severely limited in what you can do. Here is a list.
Drag or MMB+drag = Tweak components
Shift +drag = Relax vertices
Shift+MMB+drag = Relax a certain selection of vertices
Cmd/Ctrl-click = Insert edge loop
Cmd/Ctrl+MMB click = Insert edge loop and snap to centre
Cmd/Ctrl+Shift-click = Delete components
Cmd/Ctrl+Shift+MMB drag = Move a specific edge loop
Tab+drag = Extrude edge
Tab+MMB drag = Extrude edge loop
Step 06 – Use Shrinkwrap to finish
While retopologising you will find that doing large surfaces and cylindrical objects like the arms, torso and fingers gets very tedious. A tool for simplifying these is Shrinkwrap. In this example I have retopologised the left arm. I created a cylinder that was eight-divisions round, five-divisions high and zero-divisions on cap, which I then deleted. I positioned the cylinder roughly over the arm, then went to Edit>Shrinkwrap. This snaps all of the cylinder’s vertices to the high-poly model. Then it’s a matter of selecting Quad Draw and relaxing or tweaking, and continuing with retopology.