Voxel Heat Diffuse Skinning

by meshonline in Scripts and Addons

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The story

Two months ago, I needed another 3d character for our educational product, so I quickly generated a character within 'MakeHuman', when I tried to bind the character to the armature in Blender, the result frustrated me - The hair broke into pieces, the eyes were drifting in the sky, and there were holes in the body.

If the character is watertight, Blender's built-in automatic armature deform will work very well, but artists work in their own way, they create various character components, then group them together, this is artists' most natural workflow.

I used to subscribe Maya LT from Stream platform several years ago, Maya LT has an amazing feature - 'Geodesic Voxel Binding', it can deal with non-watertight character, why not add the feature to Blender?

My goal is to achieve better result and better skinning solution, not a simple copy from May LT.

When the product was born, I was so proud of the add-on, it uses unique ray tracing technology to build voxel grid, which is super robust and accurate, and the add-on combines Blender's built-in heat map diffuse skinning tool and the voxel heat diffuse skinning tool to deal with all skinning issues, I can always get perfect results.

It's a milestone, Blender has the world's best armature deform portfolio today.

That's the story of this add-on.


Traditional heat map diffuse skinning algorithm can only deal with watertight meshes, but artists create character components in their own way, then group them together to a character, usually the character is not seamless, this often cause traditional heat map diffuse skinning algorithm to fail.


Voxel heat diffuse skinning algorithm can overcome the shortcoming, it converts the non-seamless character into a solid statue, heat diffuses in the solid statue, so we can get the most natural vertex weights.


The voxel heat diffuse skinning had already been equipped in Autodesk's Maya and 3ds Max for years, but Blender users don't have an opportunity to benefit from the feature.

Traditional heat map diffuse skinning algorithm can get much better result in detailed areas such as fingers and toes than voxel heat diffuse skinning algorithm, we can combine them to get perfect result with this Blender add-on.

We believe that all digital artists and game teams want this feature, fortunately, you can do perfect automatic vertex weight skinning within Blender today.


The interface is neat, select all the sub-meshes and the armature, click the 'Voxel Heat Diffuse Skinning' button.


Video Package: Download the HD version of the video

Watch Online: https://youtu.be/nAJhPnPM7MI

Blender Version

Proved Blender version: 2.78, 2.79



Windows 7/8/10(x86 or x86_64)

macOS 10.9/10.10/10.11/10.12/10.13(x86_64)


The algorithm use multiply CPU cores to boost the running speed, more CPU cores, more faster it runs.


The algorithm need large memory to run high voxel resolution, the computer's memory is at least 8GB

How to install

The product is a zip file named 'vhd-blender-addon.zip', unzip it anywhere, launch Blender, navigate to File->User Preference->Addons, click the 'Install Add-on from file...' button, a pop up dialog will appear, select 'vhd-blender-addon/addon/vhd.zip', click the 'Install Add-on from file...' button on the pop up dialog, the addon will be installed to Blender's addons directory.

When the pop up dialog closed, we are still on Addons page, type 'voxel' in the search box, our four separate addons will be filter out, if you are a personal artist, you just need to activate the 'Voxel Heat Diffuse Skinning' addon, other three addons are for team workflow, we'll explain later, then click the 'Save User Settings' button and close the 'Blender User Preference' window.

How to upgrade

Quit Blender, unzip the latest 'vhd.zip', replace all the old files with the new files.

To find Blender's add-on directory, switch to Blender's Python Console window, type the following commands:

import bpy


Blender will tell you where the add-on directory is.

Personal Workflow

Select all the sub-meshes and one armature, the interface will appear on the tool shelf section of 'View3D->Tools->Animation'.

Because the alogrithm will convert all the sub-meshes to one solid statue to obtain best result, you'd better select all the sub-meshes and one armature before you run voxel heat diffuse skinning.

If you are rigging for RPG games, the armature is usually not complicated, you can use the default parameters, select all the sub-meshes and the armature, click the 'Voxel Heat Diffuse Skinning' button, the result will be fairly good.

Here are the steps:

1. Select all the sub-meshes and the armature, type 'Control' key + 'P' key, from the pop up menu, click Armature Deform.

2. Select all the sub-meshes and the armature, click the 'Voxel Heat Diffuse Skinning' button.

If you are rigging for a movie, the armature is usually rather complicated, in this case, we combine traditional heat map diffuse skinning and voxel heat diffuse skinning to get perfect result:

Here are the steps:

1. Select all the sub-meshes and the armature, type 'Control' key + 'P' key, from the pop up menu, click Armature Deform->With Automatic Weight.

2. Select the sub-mesh which vertices need to be protected, type 'Tab' key to enter 'Edit' mode, type 'Z' key to enter wireframe display mode, type 'A' key twice to select nothing, use either box select tool or circle select tool to select character's hands parts and feet parts(if the character does not wear shoes), or other very detailed areas, type 'Z' key to back to solid mode, type 'Tab' key to back to object mode.

3. In the addon's interface, check the 'Protect Selected Vertex Weight' button, all the selected vertices' weights will be merged to new weights which generated by voxel heat diffuse skinning.

4. Select all the sub-meshes and the armature, click the 'Voxel Heat Diffuse Skinning' button.

Team Workflow

If you have a powerful server, for example, the CPU has 32 cores or more, you can greatly boost the speed by distribute the voxel heat diffuse task to the server.

From the 'Blender User Preference' window, activate the other three addons, click the 'Save User Settings' button and close the 'Blender User Preference' window.

Select all the sub-meshes, click File->Export->Voxel Mesh (.txt), type a filename, click 'Export Voxel Mesh' button to export a voxel mesh file.

Select the armature, click File->Export->Voxel Bone (.txt), type a filename, click 'Export Voxel Bone' button to export a voxel bone file.

Copy the two files to the server, and copy the addon's zip file to the server, unzip the addon file, there is a command line tool for each platform: Linux, Windows and Mac, you can find them in the sub-directory of 'voxel_heat_diffuse_skinning'->'bin', in fact, the actual task is done by the command line tool.

Open a terminal window, run the command line tool for your platform with no parameter, it will report the usage.

Run the command line tool for your platform with parameters, the parameters are the same as in the add-on's interface except that you need to tell it where the voxel mesh file is, where the voxel bone file is, and where the voxel weight file is.

After the command line tool finished runing, copy the generated voxel weight file to the desktop computer. From Blender's 3D View, select all the sub-meshes, click File->Import->Voxel Weight (.txt), select the voxel weight file, there is a 'Protect Selected Vertex Weight' button in the left panel, check the button if you want to protect some vertices' weights, click 'Import Voxel Weight' button to import the voxel weight file.

Auto-Rig Pro Workflow

This add-on is compatible with Auto-Rig Pro, if you own Auto-Rig Pro, you can first bind all the sub-meshes to the armature with the "Bind" button of Auto-Rig Pro, then use this addon on top.

Here is the document: http://lucky3d.fr/auto-rig-pro/doc/#skinning_binding.

How does the algorithm work?

The algorithm use ray tracing technology to convert polygon mesh to solid statue, which is quite different from Maya's method, ray tracing always generate better result than multi-view voxelization methods.

Bones generate heats, heats diffuse among the solid statue, and lose a bit heat when diffused to neibour voxels, if we iterate the process, it will reach a balance status.

We use CPU's multiple cores to boost the speed. For example, the CPU of my Mac mini (Late 2012) is 2.5G HZ Intel core i5, it has two cores, but each core supports two super threads, the algorithm will use four threads to generate solid statue and diffuse heats simultaneously.

When heat diffusing process completed, bones heats will distribute smoothly among entire solid statue, the heats values represent the influence weights of the bones.

 Though the principle is simple, a good product need to deal with lots of details.

 Our goal is to generate better result and provide better skinning solution for Blender users.

Detail of the parameters

Voxel Resolution: The maximum voxel size, default value is 128, which is suitable for most characters, you may increase this value to use high resolution voxelization, usually this is not necessory.

Diffuse Loops: Heat diffuse pass equal to 'Diffuse Loops' multiply 'Voxel Resolution', default value is 5, which is enough for all cases, you don't need to change this value.

Sample Rays: Use how many random rays to detect darkness, default value is 64, more sample rays, more accurate the solid statue, but runs more slower.

Influence Bones: How many bones will influence a vertex, default value is 4, which is suitable for games, you can increase this value if you are making a movie.

Diffuse Falloff: How much heat will lose when diffusing, default value is 0.2, which is suitable for most cases, more bigger the value is, more sharper the weight change will be.

Change Log


Multiple sub-meshes can bind to one armature.


Fix an install bug.


Make the add-on compatible with Auto-Rig Pro.


No longer need to apply location, rotation, and scale.


Fix an issue of controller bones, which should be ignored.

Thanks the help from 'Artell' - Author of 'Auto-Rig Pro'.

Can I modify vertices weights after voxel heat diffuse skinning?

Yes, voxel heat diffuse skinning just give you a good start point, you can modify vertices weights anytime.

Can I select multiple meshes and skin them to the same armature?

Yes, you can.

It is the new feature in the latest version, you no longer need to join the meshes to a big mesh, I hope you enjoy the new feature.

There are still a few vertices sticked together, how to fix them?

There are two ways:

1. Use 'Protect Selected Vertex Weight' feature, please watch the tutorial to learn more.

2. If there are only a few vertices sticked together, you may clean them manually as well.

When should I use the command line tool?

If you want to use higher resolution than 256, for instance, 512 or 1024, you have to use the command line tool.

High resolution mode requires huge memories, and the task will run for a long time, running the add-on within Blender may cause Blender to crash, so you need to run it as an independent task.

Another reason is that you are a team or you have powerful servers, you may build your own automated workflow by writing shell scripts, distribute the heavy task to your powerful servers.

Should I use high resolution grid?

High resolution grid works well on fingers and toes, but high resolution grid may bring side effects on other mesh parts, like the clothes, the hair, or the equipments, these parts may break into pieces in high resolution mode, it's not perfect in all cases.

To combine Blender's built-in heat map diffuse skinning and voxel heat diffuse skinning is a better solution, you always get perfect result.

Do you have any plan to speed it up?

Yes, the kernel is written in c++, and we have been optimizing the code.

The release version has achieved 3.5 times faster than the pre-release version.

I'm not sure if my computer can run the add-on?

If the CPU of your computer is x86/x86_64 architecture, you can run it.

It support 32/64 bit of Windows, while only support 64 bit of Linux and 64 bit of macOS.

Does it support 2d characters?

No, the add-on is more suitable for 3d models.

But if the armature is in the same plane of the sprite, it may work.

Does it support pitchipoy version of Rigify?

Yes, it supports both official version and pitchipoy version of Rigify, and it is compatible with Auto-Rig Pro.

Item Rating

This item has an average rating of 5 from 8 ratings by the community.

  • 89faa594d8702df7d3efa455a2ee7e6f

    papasmurf7777 11 days ago

    Awesome addon

  • D021ceea49701e2a8ba13656db986d65

    spec24 22 days ago

    Outstanding! You saved me a ton of work!!

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang 21 days ago

      I'm glad you like it.

  • Ae6b28c334750374f6a766687822bfa3

    biblesinger about 1 month ago

    This addon deserves six stars! It saved me from spending even more time on an extremely complicated mesh blenders default auto skinner couldn't tackle.

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang about 1 month ago

      My pleasure, thank you.

  • F125a89a23658f85154d13649d66ea36

    nateordie about 2 months ago

    I was always getting the "Bone heat weighting Failed" when trying to use a Rigify Armature. This add on fixed that issue for me. Now I can focus on animating instead of trying to fix 'non manifold geometry'. Thank you!

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang about 1 month ago


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    Warren Reed 4 months ago

    I am making a feature animation, with close to a hundred characters, most made in Fuse or Makehuman, with the exception of the three main characters. Fixing the weight painting on them is a headache with one character and imperfect. I just tried this out on two of them and I felt the weight of hours and hours of work fixing all of them fall right off my shoulders. I think you may have saved my life with this add on. Of all the add ons I've bought, for what I'm doing and how it's helping me, this is NUMBER ONE! thanks!!!

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang 3 months ago

      I'm glad to hear it useful for you!

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    panicq 4 months ago

    Nice addon ! The only down side for me is that unlike in maya you cannot select multiples meshes and skin them to the same armature. You are oblige to join them and then un-join them, a process that can take times with characters that have a lots of accessories :p

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang 4 months ago


  • C36da747fa61da9bfecf258e5d8d9f7e

    odederell 4 months ago

    Works great! achieves far better initials skin weights that the built-in method.

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang 4 months ago


  • 5aff122c9ed1a6a99b30080a4c6fdf3c

    Artell 4 months ago

    Excellent work, thanks!

    • 5c8bf53a460f693ddccc502417cdd696

      Mingfen Wang 4 months ago


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