Cutting on curved polymesh?!

[hidalgo]

Hello

i am trying to cut a cubic hole into a cylinder (polymesh) that i am subdividing, i am not using boolean operations, but cutting out the portion i want and then add edges, i am try with smooth edge and so on, but the curve of the cylinder brake creating a crease in the mesh, plus the hole have his border pushing out from the original mesh, how can i avoid that?

i have attached an image as reference.
thanks

[gaboraa]

Creating a clean topology would solve nearly all the problems such as you are having. Add support edges where needed. Also as far as I can understand by looking at your image, more cuts should be added in the border edge areas.

[hidalgo]

your mesh is straight, mine is a cylindrical, if you could have same clean mesh with a curved object i wouldnt mind to see a wireframe to see were i missed the point, cause the mesh i did should have a clean topology already...

[origin]

welcome to subdee hell ;)
One trick which I use very often is to shrinkwrap your shape (flat cylinder/rectangle etc) onto target surface.
Then either merge both and manually delete/reconnect quads or use this surface as guide when moving points around.
Sometimes Its much easier to work on flat surface drilling all holes, then bending to cylinder (if the target surf is cylindrical)
Of course planning ahead is always important, working first on basic shape to get overall shape perfect.
Sometimes its necessary to subdivide surface 1-x times before drilling holes...
Remember you will never have perfect result...It might be close but subdees are not nurbs

With mari and auto uv unwrappers available now, incoming Modo boolean with bevel solution might be the best thing around

[gaboraa]

Also you may consider using crease values at the edge of the holes to make a more curvy or hard edge look. Also sometimes it is more possible to get finer results with zbrush or other sulpting apps than subdivision modeling.

[Daniel Brassard]

@Hidalgo

Can you show your wireframe as well?

[hidalgo]

@origin
hehe yeah i though so from the start , anyway i am looking to find a good solution to work with as its kind of strange that xsi doesnt make "perfect" holes or cut into a mesh from scratch...

@gaboraa
would you mind show a print screen of the sphere without subd? i find strange that that on spheres cut work better then on cylindrical mesh....

@Daniel Brassard

sure, this is another mesh i did, but you can see that this mesh too, even without much visible edge around the square still have artifact on the curved faces...

[origin]

Its because you added additional edgeloops, thats why I said plan ahead ;) You can try to subdiv mesh once more then make hole, or dont do full edge loop and live with small imperfections...

[csaez]

It's not a Softimage thing, this is how subd works... I think of it in terms of tension controlled through topology, modeling is not just about the un-subdivided shape

[Daniel Brassard]

From what I see, the edge of the cylinder are not regular or well define which will create unpredictable Catmull-Clark subdivision. You need to add some details around the hole to prevent weird deformations and control the subdivision. Add some edge loops where I mark in the cylinder picture (attached) before the subd, the closer to the hole, the sharper the edge will be and try to spread uniformly the edges/quads around the holes. You will see a significant improvement.

For round hole use mx_roundish plugin which will help your workflow (Vitaly Bulgarov use it a lot)

http://maxfoxlab.com/mx_roundish.html

[gaboraa]

Just basic cuts nothing fancy here.