FAQ Virtual Population

Here you will find answers to the questions most frequently asked. If you don't find the information you need, do not hesitate to contact us.

 Which models are included in the Virtual Population and in which version are the models available?
 For what purposes can I use the models from the Virtual Population?
 In which formats are the models of the Virtual Population available?
 What are the differences between V1-x and V3-x?
 What are the differences between V2-x and V3-x?
 What are the differences between V3-x and V4.x?
 What are the computer requirements for using the Virtual Population models?
 Can I use the CAD models of the Virtual Population with any simulation software?
 How can I get the Virtual Population models V3-x (and V1-x) if I am already a Sim4Life user?
 How can I get the Virtual Population models cV3-x if I am not a Sim4Life user?
 How can I get the Virtual Family v2.x models?
 What are the Terms and Conditions to use the Virtual Population models?
 Can I get separate parts of the Virtual Population models (e.g., head, legs, torso)?
 How can I keep track of the different versions of the models?
 Are the Virtual Population models available in voxel format?
 Can I use the voxel models with any simulation software?
 Can I open the voxel models in Matlab?
 What information is contained in the .txt files associated with each voxel model?
 What is the purpose of the Virtual Family Tool provided on the DVD of the Virtual Family v1.x?
 Can I process the voxel models to generate other file formats?
 Are there any animal models available?
 In which format are the animal models distributed, and how can I obtain them?
 Which tissue properties should I use for the various tissues of the Virtual Population models?
 Do I have to cite the usage of the models?
 Who can I contact if I need more information?

The Virtual Population currently includes 15 whole-body human models. Three different versions are available for these models:

1V1-x: first generation of human models, currently distributed on request and primarily for academic use. For additional information please contact the Virtual Population team.

2V2-x: simplified CAD models featuring 22 tissue groups optimized for finite-element modeling in third-party platforms. For additional information please contact the Virtual Population team.

3V3-x: computable, high-resolution CAD models with >300 features identified; exclusively integrated with the Sim4Life multiphysics simulation platform. For additional information please contact the Sim4Life team.

4V4.x: computable, igh resolution CAD models containing >1000 segmented tissues; exclusively integrated with the Sim 4 Life multiphysics simulation platform. For additional information please contact the Sim4Life team.

Additionally, one regional head model has been developed as a collaborative effort with the US Food and Drug Administration:

  • MIDA V1.0 (ultra-high resolution head & neck model)4

4The MIDA model V1.0 is distributed in surface (.stl) and voxel format (.raw, .nii, and .mat). For additional information please contact the Virtual Population team or the FDA.

The Virtual Population models are the gold standard for computational simulations in realistic anatomical environments. Under different license agreements, the Virtual Population models can be used for academic and commercial purposes. Any military use is strictly forbidden. Note that academic licenses strictly limit the usage of the models to academic purposes in educational institutions such as universities, universities of applied science, and university hospitals. This excludes in particular, but not exclusively, commercial product evaluations financed by partners with commercial interest, even when performed in educational institutions.

Thanks to the efficient and powerful physics solvers embedded in the Sim4Life platform, the V3-x models are the absolute go for exploratory research projects, in silico R&D, medical device evaluations, and personalized medicine applications.

The V2-x models are tailored for finite-element modeling in any third party platforms.

Depending on the version, different file formats compatible with different simulation platforms are available:

  • the V4.x and V3-x models are distributed in CAD format (.sab), exclusively integrated within the multiphysics simulation platform Sim4Life. These models cannot be imported in any other software
  • the V2-x models are distributed in an unencrypted surface mesh format (.stl) and are open to any third-party software
  • the v1.x models are available in both CAD format (.sab, compatible only with the simulation platforms SEMCAD X and Sim4Life) and in voxel format (.raw)

V1-x is the first generation of our models, originally developed for electromagnetic exposure evaluations. V3-x is the newest generation of models, greatly enhanced and suitable for a broader range of applications. The enhancement includes a re-segmentation at higher resolution (0.5 × 0.5 × 0.5 mm³), a more-consistent tissue assignment, and an enhanced surface processing method. Moreover, internal guidelines and a system of quality control have been implemented and applied to ensure that the segmentation is consistent, both within a model and amongst models.

The V3.0 models are static models, i.e. their posture cannot be modified. The computable cV3-x models offer posing functionality, i.e. the their posture can be changed to simulate various exposure configurations. Two approaches have been used to achieve the posing functionality: (i) up to cV3.0.1 a volume-preserving, skeleton- and influence-region-based approach has been used, later upgraded in the (ii) cV3-1 models to a new biomechanics-based FEM Poser tool that treats the body as a hyperelastic material with rigid bones.

V3-x is our high-resolution generation of human models, each including more than 300 anatomical features. The Virtual Family V2-x models (Ella, Duke, Billie, Thelonious) are a simplified version open to any third party platforms. In the v2.0 models, the approximately 300 tissues of v3.0 are combined into 22 high-resolution tissue groups (identical in all 4 models, except for the reproductive system, which is gender-specific). Note that the simplification entails the tissue number, not the tissue resolution (the whole body cell count ranges between 3.6 - 7.7 million cells); unfortunately, some software tools are not able to deal with such high cell numbers.

V4.x is based on the V3-x generation of models. More than 1000 anatomical features are included in each model. Segmentation is performed at an increased resolution (01 x 0.1 x 0.2 mm), allowing for more detail in objects and segmentation of small structures. The higher resolution yields an extended cardiovascular system and a peripheral nerve network (from the cranium and spinal cord to internal organs and major muscles). Muscles, nerves, and blood vessels have been named, and meshed as separate objects.

Using the CAD models requires a 64-bit operating system and at least 4GB of RAM for the V1-x models and 6GB for the V3-x models. Depending on the resolution, the memory requirements for loading and processing the voxel models can be very high.

The CAD models in .sab/sat format can only be used with the simulation platforms Sim4Life (V1-x and V3-x models) and SEMCAD X (V1-x models). The V2-x models are distributed in an unencrypted surface mesh format (.stl) and are open to any third-party software. The same as v2.x applies to the MIDA model v1.0.

If you are already using Sim4Life you can download the cV3-x (V3-x and V1-x) models from our website. The download procedure starts with a click on the model's DOI number. To generate the Authorization Code launch Sim4Life and click Help - ViP Download Code in the menu bar; type your email address and choose the models you require. Hit Apply to create the download code for each model that you have in your license. Note that each code is valid only for the model it was generated for, and the download link will only be active for 24 hours. If you require a model not included in your license, please contact the Sim4Life team.

If you are not a Sim4Life user, please contact the Sim4Life team.

The four Virtual Family V2-x models (Ella, Duke, Billie, Thelonious) are distributed free of charge for everyone (except for a handling fee) and can be downloaded directly from our webpage. Click on the model of interest to be re-directed. The download procedure begins with a click on the model's DOI number. Upon successful payment you will receive a download link by email.

When downloading the models from our website you will be re-directed to our Terms and Conditions of user license. If you have any specific question on the usage of the models, please contact the Virtual Population team.

The Virtual Population models are currently distributed only as whole-body models. However, as our mission is to continue to meet the needs of the modeling community with more precise and more detailed 3D anatomical models, we are committed to producing a range of ultra-high resolution models of specific organs.

To provide the users of the Virtual Population models with permanent digital access to each released version of the models and guarantee their unambiguous traceability, we have generated unique Digital Object Identifiers (DOI) for all the models we have released. Note that the DOIs do not vary with builts but with versions.

Academic users can receive the four models of the Virtual Family (Ella, Duke, Billie. Thelonious) V1-x in voxel format (.raw) free of charge (shipping and handling fees excluded). To receive these models, please contact the Virtual Population team. Additional pre-voxelled v1.x models are available upon request for a license fee. For enquires about the available voxel models, please contact the Virtual Population team.

The voxel models (.raw) can be used with any compatible FDTD-based simulation software.

Yes. You will need the 'Read Medical Data 3D' function from Dirk-Jan Kroon, which can be downloaded at

Unzip the folder and copy it into the working Matlab directory. You can then use the following command (assigning to variable A) pointing to the location of the RAW file:

A = ReadData3d('FileDirectory\Filename.raw');

In the pop up window that appears, specify the image dimensions (x,y,z) equal to the number of cells along the x-, y-, and z-axis to match the input file dimensions.

The RAW file information will be loaded into the variable 'A' and you can process it further. For example, you can view the image of slice z=300, by using the following commands:



Each voxel model (.raw) comes with an associated descriptor file (.txt). In this file, the first column gives a unique index for each tissue. Columns 2 to 4 are color codes for the tissues in SEMCAD X and Sim4Life. The last column shows the tissue name. The number and size of the voxels along each direction (x,y,z) is given at the end of the document.

The Virtual Family Tool can be used to generate voxel models that might be more suitable for your specific needs i.e. different resolution. The Virtual Family Tool is only distributed with the Virtual Family V1-x DVD for academic use. You will find a user manual ("SEMCAD-X Manual.pdf") in the Documentation folder of SEMCAD Light. Chapter 9 is dedicated to the Virtual Family v1.x and the Virtual Family Tool. Note that the second term on the right-hand side of equation (9.1) should be j*nx, and not j*ny.

No. Decrypting or disassembling the voxel models or any part of the Virtual Family Tool is not permitted. Retrieving information by reverse engineering of any kind is also prohibited.

At the moment, the animal models comprise five rats, five mice, and one pig model:

1V1.0: first generation of animal models. The animal models are available free of charge for academic use and for a license fee for commercial use. Please contact the Virtual Population team for additional information.

All animal models are distributed in CAD format (.sab) compatible only with the simulation platforms SEMCAD X and Sim4Life. The Big Male Rat, the Male P1M1 Mouse, Diggy Mouse, and the Male Pig models are provided in a 3D CAD format; all the other animal models are distributed in a 2.5-D CAD format.

Sim4Life users can download the animal models from our website by generating the authorization code in the Sim4Life Help menu (see question 8 above).

The IT'IS Foundation maintains an up-to-date online database for the EM, thermal, fluid, acoustic and MR properties of biological tissues. All Virtual Population models (human and animal) are fully compatible with the tissue properties database. With the Sim4Life and SEMCAD X simulation platforms, users are able to import the material database and automatically assign tissue parameters values to the Virtual Population models.

In the models optimized for Sim4Life (V3-x and cV3-x) all anatomical features are already identified by an associated material tag, thus reducing the steps required to assign material properties during the simulation.

Yes. The models must always be cited. For the Virtual Family v1.x models, the reference is Christ A, Kainz W, Hahn E G, Honegger K, Zefferer M, Neufeld E, Rascher W, Janka R, Bautz W, Chen J, Kiefer B, Schmitt P, Hollenbach H P, Shen J, Oberle M, Szczerba D, Kam A, Guag J W, and Kuster N, The Virtual Family - development of surface-based anatomical models of two adults and two children for dosimetric simulations, Physics in Medicine and Biology, 55(2):N23-N38, 2010.

If additional V1-x models are used, a reference to our webpage ( is also necessary.

For the V3-x and V2-x models, the reference is Gosselin M C, Neufeld E, Moser H, Huber E, Farcito S, Gerber L, Jedensjö M, Hilber I, Di Gennaro F, Lloyd B, Cherubini E, Szczerba D, Kainz W, Kuster N, Development of a new generation of high-resolution anatomical models for medical device evaluation: the Virtual Population 3.0, Physics in Medicine and Biology, 59(18):5287-5303, 2014.

For the animal models, the following reference shall be used:

Our support team will be happy to help you.



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