Zbrush 4r7 Weird pattern after subdivision

#1

Hi, As a beginner i follow the Digital-tutors Quick start to Zbrush Volume 1. On the 8th video (for those who might have done it) The guy ask to Divide (Ctrl+D) a basic cylinder.
At this point on the video this happen :

Info : They have Zbrush 4r5.

Before Subdivide :

After Subdivide :

So now, when i try to replicate that (and i made a video of it ) I have erratic problems.

1st : When i convert my cylinder to a polymesh3D it get a Orange/brown color, OR a Dark red color. can’t figure out why.

2nd and most important when i Divide the cylinder the chamfer on the edge got a star like pattern.

3rd and even weirder, i tried to use the file from the tutorial (base cylinder ) and when i divide the center of the cylinder become hollow !

Here is the video :

//youtu.be/5QymG4QbSjo

#2

Unticking Smt (smoothing) before subdividing will retain the shape.

#3

[QUOTE=Alroc]

1st : When i convert my cylinder to a polymesh3D it get a Orange/brown color, OR a Dark red color. can’t figure out why.

2nd and most important when i Divide the cylinder the chamfer on the edge got a star like pattern.

3rd and even weirder, i tried to use the file from the tutorial (base cylinder ) and when i divide the center of the cylinder become hollow !

1 - this is just the polygroup changing colour, perfectly normal.

2 - this is because when you divide the mesh the triangles on the polar cap of the cylinder are converted to quads and the bad topology is causing subdivision artifacting.

3 - the cylinder that you loaded from the file looks like it had an extra edgeloop extremely close to the polar vert(at the centre of the cap) and the resulting inner triangular polys were deleted. This means that the cap is now quads and results in a much cleaner subdivided mesh.