I am trying to investigate AnyShortestPathMuscles. I have a model with a cylindrical surface and this seems to run fine. However when I try to change the cylinder for a sphere of the same radius the following error occurs:

ERROR(OBJ.LIB.OOS1) : E:/AnyBody_Monique/W…s/WrappingObjects.any : WrappingMuscle.SPLine : Unexpected exception in the library OOSol :
OOSol exception : MISSING MESSAGE.

I do not know why this error occurs as the path should be identical in the two cases (for the simple application I have with the cylinder perpendicular to the muscle path). Also the error message does not seem to give me many clues.

Any help on this would be greatly appreciated. Thanks.


Hi Monique,

This is most likely a deficiency in the wrapping algorithm.

The usual remedy to resolve such problems is the following:

[li]Increase the number of points on the StringMesh property.
[/li][li]Look at the way the muscle wraps visually by drawing the object it wraps on. Notice if the error happens when there the muscle slides sideways rapidly or is about to slide off the object, then the remedy is to change the geometry to avoid this slipping phenomena.

Best regards

Hi Soren

I am surprised as this is a very simple case with the muscle path restricted to the xy plane and wrapping over the centre of the sphere. I tried increasing the number of points on the stringmesh property but this did not help.

Are prefect spheres prone to errors? Would increasing the radius in one direction slightly help? Within the shoulder for example there is a sphere at head of the humerus - is this sphere defined such that the radius is the same in all 3 directions?

Thanks for the help


Hi Monique,

Usually the error occurs if the string is about to slide off the object sideways.

Did you try to visualize what happens when the error occurs?

I did not understand how you constrained the string to move in the XY plane only?

Spheres are not more prone to errors than other objects in general, but depending on the location of the insertion and via points node you can easily create a model where the line would tend to slide off the sphere. This would typically not happen on a cylinder.

So it is important to visualize what is going on, you can use the AnyDrawParamSurf object inside the AnySurfSphere for this.

There is a small example on the use the wrapping surfaces available at in the reference manual if you search for AnyKinSPLine (look at the bottom of description) maybe this can be useful.

Best regards