Pose User-Defined Surfaces/Entities

bryn

I guess you mean normal (to skin) direction, not vertical direction? The move tool has a sub-tool that allows to align an entity with a target direction. Probably it could be used to align the antenna with the grid.

If I learn how to use it I will post a gif animation. Else, if you figure it out, please share.

VigneshYork

Yup normal to the skin surface. Okay, thank you

bryn

You can place a local grid on the surface (or multiple). In the video below I first

select a triangle on the mesh
create a patch
extract it as triangle mesh
and then place the local grid on this triangle

I think this may not be necessary, i.e. you could directly place the local grid on the surface. But maybe the procedure above can help to make it more precise.

An easy way to apply the transform is to get it in Python:

# assuming you select the WCS and then the electrode
wcs = XCoreModeling.GetActiveModel().SelectedEntities[0]
device = XCoreModeling.GetActiveModel().SelectedEntities[1]

device.ApplyTransform(wcs.Transform)

This assumes the "device" was centered at the origin, and aligned with the z-axis. If this is not the case, you should first position the template antenna/device with the z-axis at the origin.

Youtube Video

VigneshYork

Hello Bryn,

That looks perfect. Thank you

VigneshYork

Hello Bryn,

Thank you for your support. I have one question regarding the ViP models:

If you change the properties of bone (cortical, cancellous and marrow) to that of muscle, would they all merge together when you build the voxels? For example, if I apply a microwave imaging algorithm to the leg with all bone properties changed to muscle, would I get scattering due to muscle-bone interface? Is this scattering due to difference in properties or due to the shape ?

Thanks

bryn

The solver will treat the bone as muscle tissue,ie the properties matter. There will be no bone muscle interface.

VigneshYork

Thank you. I have one last question: Are there any tutorials using the FDFD solver?

VigneshYork

Hello Bryn,

I would like to confirm the difference between the option "distribute along line" in the sources settings.
Does not choosing the option introduce a time delay/phase delay for the antenna (patch antenna) for example? Is there a method of calculating the time delay for an antenna?

Thanks
Vignesh

bryn

Hi @VigneshYork

Please open a new topic. The questions about FDFD (yes there are tutorials) / source settings are unrelated to the poser.
This will help make the forum more useful for others (or you, next time). It also is more likely to get answered by somebody who knows the topic.

Thanks

VigneshYork

Hi Bryn,

I apologise.

Thanks

VigneshYork

Hi,

I have two questions regarding the pose tool:

In the example stated at the start of this thread regarding drawing a patch on the surface of the skin and posing the patch with the model: would the patch also deform similar to the skin? Is the FEM applied to the patch also?
I am getting the following issue (figure attached). The bone and muscle are split. I am not sure how to fix this

Thanks

bryn

the FEM model is used to compute a deformation in the entire body. The deformation is applied to all surface entities (and patches defined on those surfaces). A patch on a triangle mesh is actually just a subset of that surface (a list of triangles).
I have never observed this issue. Did you use the move tool before/after/while using the poser? Can you explain the steps to reproduce this issue?

VigneshYork

Hi Bryn,

Thanks for your clarifications.

If I extrdue the patch to make a cloth or band around the leg. Would that deform too?
The way to reproduce the issue is to move the model to a different location and then pose it.

Thanks

bryn

ok,

if the extrusion layer is thin enough it may deform reasonably. Deformation of surfaces outside the body is based on nearest neighbor extrapolation. You could also extrude the patch after posing.
Thanks, I will create a bug report so we can address it. I guess a workaround is to move after posing. Sorry for the inconvenience.

ofli

@VigneshYork Which Sim4Life version are you using?

VigneshYork

Hi, I am using version 7.0.1.8169

ofli

Please download and install the latest version of Sim4Life (V7.2.4) with which you should not experience this issue.

VigneshYork

@bryn I have a follow up question to this. If I draw a cylinder over the bone and provide it properties of muscle, do I need to subtract the bone from the cylinder?

For example: When I observe the voxels in the ViP model for muscle only (without the presence of bone or anything), there is a hole where the bone is suppoed to be (which makes sense) (Figure attached).

Do I need to do the same with a custom cylinder i.e subtract the bone from the cylinder? The voxels with the cylinder with bone shows the presence of the bone (Figure attached) but not for all cases.

Thanks

bryn

you can, but it is easier to simply use the priorities. if you set the cylinder to a higher priority than bone it will be voxeled over the bone. a voxel can only represent one material, so what ever has higher priority wins.

VigneshYork

Thank you. What happens when all elements are given the same priority and you do not subtract the bone from the muscle? What would a voxel at the location of the bone present?

@ofli : Thank you. Installing the new version removed the error.

ZMT zurich med tech

Pose User-Defined Surfaces/Entities