Foot Insole Modelling

[dannytso]

Hi there,

I am very new to CAD and this community. Thank you to everyone who has contributed to putting together Fusion 360. As a novice, I am having a lot of fun playing around with the functions and making simple designs. I especially enjoy the sculpting tools but I definitely need more practice and more learning.

I would like to learn how to model a custom insole to match the plantar surface of a 3D scanned foot.

My first attempt involved loading the 3D mesh into the workspace and pulling a planar t spline body towards the foot. Although the resut somewhat follows the contours of the foot it still is quite distorted and undesired. Is there a way to achieve a cleaner result? I have also tried decreasing the number of triangles on the 3D mesh using Meshmixer but still no help. Perhaps I should change the shape of my planar t spline before pulling? Thank you in advance!

I have included some images of my first attempt. Please be kind!

[Anonymous]

Wow that sounds like a fantastic idea! What I would be tempted to do is, in Model environment, go to Create > Create Base Feature, then Modify > Mesh > Mesh to Brep and select the model to convert to a Brep body. It looks like your mesh will be under 10,000 faces, which is the informal limit for that conversion. You can then create a Construction plane (such as offset) to use as the splitting tool in a Split body operation, so that you can then remove the top portion of the foot. If you would like, you can then go into Sculpt environment and Modify > Convert then choose the Brep face option, and should be able to convert the bottom of the face into T-splines (which don't work well with too many faces, hence the need to remove the top part of the foot first). Then slight adjustments to the Tspline mesh can be made if desired.

I would be interested to see how this turns out for you. Be sure to post if you run into any trouble with this method or another.

Jesse

[Anonymous]

Hmm, the second part I mentioned, the Brep to Tspline conversion, I forgot will give trouble if lots of faces, so a Tspline pull like you're doing is the way to go.

Jesse

[dannytso]

Hi Jesse,

Thank you very much for your help. I tried what you have suggested and you are right it cannot be converted to a t spline. It says it contains too many triangular polygons. I hope working with models with quadilateral polygons will allow for t spline conversion. 

The pull method seems to not work very well and I am not sure why. I will post here if I learn anything new. Thanks again.

Danny

[Anonymous]

Hi Danny,

I've determined a method to get pull to give an extremely good result, will describe fully this weekend. 

Jesse

[dannytso]

Thanks Jesse. I look forward to it!

[Anonymous · Accepted solution]

Alright, I made a video outlining how I get very good Tspline meshes from irregularly shaped imported stl or obj meshes.  The key is to create a multiple profile Tspline loft that is itself quite close to the original mesh, before doing the Tspline pull operation.  It's just asking too much from the latter operation to not have the Tspline mesh as close to the original mesh as possible first.  

Note that prior to making the video, I converted the foot stl mesh to a Brep, and split that body to only work with the needed bottom of the foot.  This could be done in a different program like Meshmixer or Meshlab before importing.  Once the bottom of the foot was a Brep body, since that split operation was done in Fusion, I also made a copy that I converted back into a mesh which is best for the Tspline pull operation.  If you have trouble with any of this or anything in the video be sure to let me know.  One final note is before the multiple profiles method as done in the video, I tried multiple rails beyond just the two, however for such geometries the multiple profiles in proper locations is definitely the way to go, to properly instruct the loft algorithm and avoid ripples, etc. 

Here's the end result

And here's the video.

I hope you can make many good shoe insoles to come using this method! (I'm also curious of the general process you use to fabricate them). 

Jesse

[Anonymous]

If you would like to refer to the .f3d file it is here

https://drive.google.com/file/d/0B5QYSSum8lOyR0xBVHJuZkVDeWc/view?usp=sharing

Also wanted to mention that while it appears there are several steps in that video, once you know what to do it actually is quite a fast process. 

Jesse

[dannytso]

Hi Jesse,

You are awesome man! I need to go over your video many more times but I just want to say good work and thanks for being such great help. The end result looks fantastic is what I am aiming for.

One questions I have for you is:

I am confused why you needed to sketch over the initial cross sectional profiles. Are those profiles not spline sketches themselves? 

This is great I am currently on my first attempt!

[Anonymous]

I learned a lot from your question, it's nice to know now how to get great Tspline meshes from imported scanned meshes and what not, getting the Pull tool to finally work like I always wanted it to! 

Regarding retracing like that, if you try to use the curve from Intersect as a loft profile, you'll notice it looks at every curve segment as a separate profile for some reason, making quite a mess of the loft, whereas the new spline is looked at as a single segment/profile.  

Be sure to view the video in a larger size and higher resolution...sorry if I sped it up too much 😉  Let me know if you run into trouble. 

Jesse

[dannytso]

Thanks Jesse. I'm happy to hear that you also benefited from helping me. Its always good to get to gears running a different way!

I've attached some images so you can see what I have done. I used sectional analysis and I just drew my splines along the path of each cross section. I didn't manage to do the intersect function but it still lofted so I'm not sure if its ok or not. 

Can you think of a way to wrap the mesh nicely around the heel area too?

[dannytso]

When I get to the point when I have a functionally designed insole, I plan to mill these through general CNC processes. 

[Anonymous · Accepted solution]

And keep in mind there's lots of various things involved here to learn, so give yourself some time to get familiar with Fusion 😉

When doing Intersect in a sketch, be sure to note there are two selection choices, body or specified entities, be sure to choose the right one. 

Also after make points of intersection, be sure to turn off all other sketches but current one when drawing spline (problem I often made only to find out not properly connected when doing loft). 

Here's a Tspline mesh and resulting surface I made that includes the heel. 

I basically started over with the rails, first adding another profile by having the sketch/construction plane barely nick the back of the heel (can use single point as a profile, but found it would not work with all the profiles and rails involved). 

After the loft and pull.

After exiting Sculpt environment, I mirrored the surface so I could do a patch of the hole (there are ways to get an even better patch surface, but this should be good enough).  Once the patch was made, I deleted the mirrored surface and split the patch and deleted half of that.

Yeah, it's definitely going to take some getting used to, but at least you know it's doable, and not too bad once get familiar with everything.  In fact, I'm putting together a comprehensive learning system for Fusion 360, if you sign up for the mailing list at hobbymate.net, you'll get updates.

Very cool about the machining 🙂

Jesse

[Anonymous]

It's kind of hard to see what's going on in your pictures.  If you run into trouble you can export the model as a .f3d and upload it here or to Google drive for people to take a look at.

I forgot to mention about patches in the Patch environment, that good to use tangent or smooth option. 

Jesse

[Anonymous]

Just for future reference, I just found can create a patch loft, exploiting if needed the tangent and curvature options with respect to previous patch loft, then in Sculpt environment can convert the Brep surface to Tspline (a little confusing since can barely see Brep surface in Sculpt environment and Brep body/surface does not show up in browser).  I had to convert two Brep lofts seperately, even if stitched, but then can merge edges of these two Tspline meshes.  I then did a pull and got a near identical result to what I got starting with the Tspline loft.  

Jesse

[dannytso]

Its good to see you have found more than 1 way to accomplish this task. Great tip on how to capture the curvature of heel area. 

Your instructions and explanations are very clear. However I am still not able to loft as nice as you. Perhaps you can take a look when you get a chance?

I have included the .f3d file for your consideration. Thanks for getting me this far. 

[dannytso]

FYI during the loft function, what goes wrong is I cannot seem to select the side rail to connect my profile sections. I click on all the profile curves with chain selection unchecked then I click "New Input" and attempt to select the side rail but it gives me an error saying the loft will intersect itself. I think you briefly mentioned why this may happen but I'm not sure what I need to change. I'm learning a lot but have a long long ways to go it seems!

[Anonymous]

Hi, I looked at your model, and that's some good progress! I successfully lofted everything but the largest profile (since it visibly does not touch the rail on one side). I did not mention an important detail, that to add a rail, first select new input, select the rail spline, then choose Convert to Rail in Loft dialog window/pallet.

I also noticed you don't have a copy of the imported mesh converted to a Brep, by create > create new base feature, then going to modify > mesh. This Brep of the foot is necessary for the Intersect sketch operations. Because the profiles are not right on the foot mesh, the resulting Tspline pull results in lots of ripples when it trys to shrink the Tspline mesh onto the foot, and in this case even gets an error when trying to finish due to Tspline crossing. So I think it's important to use the Intersect method for your profiles...the Brep body is probably what you were missing, but if not we'll figure it out.

For my method I think it's good to also slice/split the Brep conversion on the top too, so that get a nice tan projection of the slice top into a sketch defined on the slice top.

Jesse

[Anonymous]

Here's your model with the loft and pull (for no particular reason I did it in Patch environment then converted to Tspline as I mentioned is possible).

Jesse

[dannytso]

Thanks Jesse.

I can't seem to open your file as my version does not currently support opening of local files.

Could you please provide an explanation on how you made your initial profile shapes? I can't seem to make mine intersect the top face of my Brep foot, the face I see all your profile cross sections are connected to. In other words, how did you produce the shapes you then traced over with the spine command?

What I have been doing is I am using sectional analysis and drawing a spline around the shape of the cross section but there is a lot of guess work here and your way appears more precise. Thanks again.