Mesh2surface


#1

Hello all,

I am recently using Rhino and grasshopper for creating lattices. My primary goal is to create lattice between 2 surface. However, I do have mesh (.stl files) not surfaces. I would like to know what is your suggestion to create a surface from my mesh.

I tried some ways:(a) I used the contour+loft but it did not work well
(b) I used mesh2nurb, but it creates polynomial surfaces not a unit surface, and the patch command is so slow and does not work for me well.

My surfaces are not complex, but I need good accuarcy. Any solutions with Rhino or grasshopper would be appreciated.

Thanks!


#2

if its simple geometry as you say it may be just faster to rebuild it. you can use this icon which is located above the reply field to upload a sreenshot of what you are dealing with.


#3

Thanks for your reply.

Is it possible to rebuild surfaces in Rhino? If yes, what are the possible solutions?

This is a [photo](http://

) of my geomtry. I just showed the contours to see it is a simple one. However, I might sometimes have more complex ones with some holes inside the area.


#4

oh this is rather a complex shape, it will require to be very precise i presume. so rebuilding it will not be that easy even though possible to a certain degree in a rather easy way but depending on how exact the outcome shall be.

the simplest way to create this surface would be to contour it in both directions with a closer spacing the closer the better of course, also duplicate the boarder of it, then select all curves and patch. maybe there is a better more precise way, so use that with caution as a first instance.

just be sure the outline touches each contour line if possible, that will help creating one trimmed complete surface.


#5

you could also just use a tight one directional contour along the long side and use loft maybe thats even better and no need for a boarder curve then. but just try both options.

so maybe quite possible after all :slight_smile:


#6

Thanks for your help.

I have tried with very close contours and lofting. The problem is that Rhino consumes much more memory than Catia. It just sends me low memory after like 15 minutes of working. Do you recommend to use Rhino, Grasshopper or another software, if you are used to reconstructing surfaces?


#7

hmm if you keep the complex mesh object in your rhino file it may consume quite a bit so deleting not needed objects and a Purge and a HistoryPurge from time to time might do well, other than that i cant judge wether its the best option for resurfacing. i read that it has not been a lot of fun generally using catia and rhino together but thats just 2nd hand info.


#8

Try rebuilding all the curves you create from the contour, using the ‘Rebuild’ command, to reduce and equalise the point count and simplify the lofted surface.

This will greatly reduce complexity.


#9

yes true a FitCrv before lofting could do well not to lose the complexity of the curvature.
but i would be careful with just rebuilding it.


#10

Thanks for your comments.

FitCrv also works like adjusting the points on curves?

It seems a good idea to have the same number of points in all curves.


#11

yes that would be optimal for lofts anyway if you could achieve that. but fit curve will only rebuild the curves to its optimum accuracy to the tangency as i have experienced. you can use rebuild after that to equal the points for all curves but that can also break accuracy so do that with caution.


#12

Great thanks.

lets try with different tricks. I would write back.


#13

The problem is that it makes my polynomial surface. In intralattice, when I want to set a surface, and select it, I can not select the whole surface.


#14

you mean the outcome of your surface rebuilt is too complex? if yes you can also try to rebuild the surface with FitSrf to lower the control points, you may have to set the tolerance level to 1 or here or similar. or even just rebuild or rebuild uv but that also goes along with a decrease of accuracy.

it really depends also on how you want to work further with this data, if its lets say for some shoe design and you only need the basic shape of that then you can do anything up to the point of rebuilding it with 3-4 newly drawn lines in respect of the outline you have. but if you need that for something more precise in matters of a custom fit prosthesis you may have to stick to accuracy.

one more way i have though of is that you could take the vertices of the mesh and extract the relevant points to create a point cloud surface.


(Pascal Golay) #15

Hi Mary - can you post an example mesh, if that’s allowed?

-Pascal


#16

When I apply loft to my contours, it make the surface like picture 1. It makes me some problems in the highlighted areas when I want to create lattices. I can not increase the size of my latiice between the 2 surfaces because they intersect with each other in these sharp areas.

Is there anyway to do the lofting with some directional lines to avoid these sharp areas?


#17

you could extend the contours to a rectangular or tending to one around the whole shape loft it as such and trim it off again along the boarder when you are finished.

or maybe better you create the lattices over that surface manually 2dimensional with tween for example or just by hand or similar means which create regular curves of your need, extrude them through the surface and intersect.


(Tim) #18

Try to patch it but prepare the curves first. I know, it would be a terrible shoe sole, but it is to show the surface structure if you need something like that.


#19

Hello,

Many thanks for your reply. After doing the patch with these curves, the
insole is out of the borders of the foot. Is there any way to define the
boundries around the stl file and then cut the patched areas with the
boundries?

Kind Regards,
Maryam


(Tim) #20

Yeah, I guess one does not simply dupborder an stl mesh XD. Without the model I can only guess, I don’t have any mesh model here, can’t help with the border, I assume there is something like dupborder for the mesh, though. Check it out.