Human geometry mesh

[Logan Szajnecki]

Hi all, I would like to make use of the human geometry features in OpenVSP. Specifically, I would like to create a CFD mesh of a human OR export just a simple human geometry as an .igs file. I am having some trouble doing this. Is this something anyone has experience with? Let me know if this is not possible in OpenVSP and if aircraft surfaces must be present to create a mesh and/or export geometry. Thank you!

 

[Brandon Litherland]

CompGeom will work on the Human mesh component but I doubt very much that CFDMesh will run on it because there isn't an underlying Bezier surface.  Similarly, you won't get an IGS out of this.  Fundamentally, it's a collection of tris skinned over a complex internal skeleton of points that has been parameterized very cleverly.  However, you can mesh the surface and export as TRI or STL and then bring that into something like Pointwise and mesh it up there.

What is the goal of this process?  What are you trying to accomplish with the Human Geom?

[Rob McDonald]

As Brandon said, the HumanGeom in OpenVSP is a glorified bag of triangles.  This means it can only work for certain operations.

The 'normal' components in OpenVSP are constructed from analytical Bezier surfaces.

Most significantly for your question, it is impossible to export the HumanGeom to STEP or IGES formats.

The HumanGeom was based on work from a research group at the University of Michigan.  Their main website has an anthropometric person here.  In addition to the standing male and female forms in OpenVSP, they have some sitting forms and some for children.  Their research is mainly automotive human factors -- things like seat belt safety research.

The University of Michigan stuff is not poseable -- that is something I did on the OpenVSP side (using tools from the gaming and animation world) to skin a skeleton and make it poseable.

The University of Michigan mesh was very fine resolution -- much finer than I wanted to burden OpenVSP with.  So, I spent considerable time de-res'ing the model.  So, if you want a higher quality model of the same thing, then you should look at their website - once you set the age, height, and BMI, you can download an OBJ or STL file.

If you really need to be able to pose a higher-resolution model, you could hack on OpenVSP for a bit to make a version that had a high-resolution human form in it.  The higher resolution would mostly a help a posed model -- places where the base model is flat / straight -- but that move a lot when posed.  For example, the knee is pretty terrible when bent.

Rob

On Fri, May 13, 2022 at 6:47 AM Logan Szajnecki <lszajn...@gmail.com> wrote:

Hi all, I would like to make use of the human geometry features in OpenVSP. Specifically, I would like to create a CFD mesh of a human OR export just a simple human geometry as an .igs file. I am having some trouble doing this. Is this something anyone has experience with? Let me know if this is not possible in OpenVSP and if aircraft surfaces must be present to create a mesh and/or export geometry. Thank you!

 

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[Logan Szajnecki]

Hi there, thank you for your time. I am trying to accomplish a CFD simulation of a skydiver in an indoor skydiving facility. To do this, I need a reasonably high-resolution model of a human taking on a "skydiving position." I have used OpenVSP in the past and I would like to make use of the Human feature, but developing the mesh in Pointwise is proving to be difficult. Like Rob has mentioned, the low resolution model in OpenVSP is not very suitable for posing, so adjusting its parameters to a "skydiving position" is proving to cause meshing issues in PW.

[Rob McDonald]

The person posing is done using techniques from the animation world -- it is not precise in a medical sense.  A skeleton is placed within the skin -- the skin is associated with the skeleton based on some sort of distance metric.  When the skeleton is re-positioned, the skin is stretched.  It does not do well for large deflections -- for example, the arm-pit gets distorted when the form reaches above their head.

The best you can do with OpenVSP is to use a high-resolution version of the Human model.  You'll need to compile OpenVSP yourself to accomplish this.

I've hacked together a full resolution human model and pushed it up to GitHub here.  This includes the complete mesh from the Michigan data.  I did have to trim the floating point precision  (and split the male/female files) in order to get the file size under GitHub's limits.

Hopefully this will do better for you -- no promises...

Rob