Our thanks to Sami Tarvainen for this tutorial
Here we’ll be going over a workflow for baking textures using Blender’s Subdivision Surface/Multiresolution modifier and Substance Painter’s texture baking. The tutorial covers a variety of different processes, techniques and my favourite tools, so don’t let the title fool you!
Because this tutorial is meant to cover the processes which come after base modelling, we’ll skip the preliminary designing and the actual modelling phase and use a mask where all these things have already been done as a base for this tutorial.
I’ll begin the tutorial by showing the things that I usually do before the model is ready to be converted into a high-polygon model using Blender’s Subdivision / Multiresolution modifier. These will include adding additional edges to the model, useful tools and shortcuts – I know, it’s a lot of edge looping. The mid-section of the tutorial is dedicated to making a low-polygon version of the model by demonstrating how to remove unnecessary edges and sharpen the edges.The last part of the tutorial is mainly about the preparation of high and low-polygon models for texture baking in Substance Painter as well as the baking process in the software itself. We’ll also learn how to export the models and what kind of settings to use for exporting.
This is an advanced tutorial, and therefore knowing the basics of Blender and the knowledge of using tools would be preferable before beginning this tutorial. Saying that, I’ll try to cover as much as possible by using detailed images and describing the tools and shortcuts I use, but there will still be things that the tutorial assumes you know. I hope you enjoy reading this tutorial and – more importantly – find something helpful you can use in your future projects.
Let’s start this tutorial with something rather simple and set the Object Face Shading to Smooth. Remember to have the cursor in the 3D View, then select the object, set the Object Interaction Mode to Edit (press Tab). Select all faces (press A), click the Shading / UVs tab and set the Face Shading to Smooth. If you have an Edge Split modifier active remember to disable or remove it, otherwise you won’t see the results.
Before we move on to unwrapping the model, we’ll need to add additional edges to parts of the model that we want to maintain the original shape – this usually includes the edges and corners. The reason for this is to prevent the Subdivision Surface modifier from smoothing out the edges and distorting our UVs too much. Keep adding edges until the shading looks smooth and nothing stands out. I usually add the Subdivision Surface modifier to the model at this point so that I can see better where I need to add edges and later remove the modifier before unwrapping the model. Some useful shortcuts for this step are: Loop Cut and Slide (Cmd/Ctrl+R), Offset Edge Slide (Shift+Cmd/Ctrl+R) and the Knife tool (K).
At this point of the tutorial it’s time to unwrap the model – no tricks here, just good old-fashioned unwrapping! After unwrapping the model, make a duplicate of it. One is going to be the low-polygon model and the other is to be used for sculpting and as a high-definition model for baking textures in Substance Painter. Some useful shortcuts for this step are: Select Linked (Cmd/Ctrl+L), Select More (Cmd/Ctrl+‘+’) and Select Less (Cmd/Ctrl+‘-’).
Now it’s time to make the high polygon version of the model, which is going to be used as a high-definition model for texture baking in Substance Painter. For this step use one of the duplicated models that we’ve already made and then save the other one for the next step. If I need to sculpt or bake textures in Blender, I tend to use the Multiresolution modifier and if not, then the Subdivision Surface modifier will do the job just fine. If you decide that you want to use this modifier, be sure to go to Add Modifier>Subdivision Surface or Multiresolution.
For this step we’ll use the model that is going to be the low-polygon model and not the one that was used in the previous step. I prefer to do this manually, but you can use the Decimate modifier as well. I usually do the removal process by selecting the edges that I wish to remove, either by using an Edge Loop selection or by hand. After selecting the edges, press X or click the Tools tab and select Delete>Edge Loops or Edge Collapse depending on the situation. In the image, the red lines indicate general areas where I usually remove edges.
First, add an Edge Split modifier to the object by clicking Add Modifier and selecting an Edge Split. Next, toggle Sharp Edges on. To sharpen edges, first we need to select the edges we wish to sharpen by using an Edge Loop selection or manually picking. Open the Shading/UVs tab and select Edges: Sharp.
Before exporting objects we should separate and name them, so Substance Painter can recognise them correctly. Both low and high-polygon objects use the same name but a different suffix, so ‘_low’ is for low-polygon objects and ‘_high’ is for high-polygon objects. If the model is static and there’s very little clipping you can export the models as single objects, but in this case the model is dynamic and there is some clipping, so to avoid possible texture issues in baking we should separate the models into smaller pieces.
To export the models, first select the low-polygon model(s). Open the File tab, select Export>FBX. As for settings, toggle selected objects on, select Mesh as the kind of object to export, click the Geometries tab and choose Face for the Smoothing. Then export the model and name it model_low.FBX. Next, do the same for the high polygon model(s) and name the file model_high.FBX.
This part of the tutorial is pretty simple. Start by making a new project and selecting the low-polygon model as the mesh and clicking OK. Next, click the Bake Textures button and press the small document on the Common Parameters window. Select the high-polygon model and change Match from Always to By Mesh Name. Then click the Bake Textures button and wait for the bake to complete. After that, change the Texture Mixing from Replace to Combine.