[Baking/Projection Modifier] - Cage Intersecting with a Contiguous Mesh around a 'Pole'

Dan Powell

Hi Polycount,

I've built a CCTV camera model based off of some Concept art, and to save polygons I've made the main casing of the camera one large, contiguous mesh - allowing for the bake to put all of the split-line details back in.

Low Poly contiguous mesh:



High Poly mesh:



The issue is that because these parts of the object are 'poles' (kind of), the cage is going to clip on one of the sides based on the location of the vertices - and I'm not sure how to adjust he topology (or the cage) in order to fix it. The solution I'm seeing most feasible at the moment is to separate the casing into separate meshes instead of one contiguous mesh, but this sacrifices UV space/texture resolution - especially when some areas will literally, never be seen. 





I've done test bakes and these areas have caused problems in the bake due to the tightness (slight clipping) of the cage.

Cheers all.

Obscura

Select that verticle of the cage and move it?

ZacD

I would probably just add an edge or two and tweak it by hand. 

Dan Powell

ZacD said:

I would probably just add an edge or two and tweak it by hand. 

I'll add some more vertices around that area and see what I can do. Was just weary about adding more, because it's a fairly small prop (just a camera; but I like doing everything to a nice quality), and the polycount is already above 1000. Cheers.

Obscura said:

Select that verticle of the cage and move it?

Won't work - essentially the problem is no matter which direction I move it, it's going to clip something because of how the five edges meet it. Cheers.

Dan Powell

Even with more topology, haven't been able to improve the result much.

It may be a case of having to accept defeat, and making a non-contiguous mesh - will make the cage much simpler, but wastes UV space. 

ZacD

Mind posting the mesh? I'm sure there's a better solution.

Dan Powell

Sure - uploaded the scene to dropbox. 

https://www.dropbox.com/s/r2su443no0xfnba/CCTV6.max?dl=0

Cheers.

AtticusMars

Dan Powell said:

Even with more topology, haven't been able to improve the result much.

It may be a case of having to accept defeat, and making a non-contiguous mesh - will make the cage much simpler, but wastes UV space. 

I wish you'd have uploaded an obj/fbx because I would have liked to have been able to see this mesh since I'm a little confused as to how this would cause you to waste any UV space at all, you have hard edge splits everywhere so this mesh must be a decent number of UV islands already.

It hasn't been mentioned yet because it's bad practice, but I've had this problem before and I simply painted it out in photoshop. So if you need a last resort...

Dan Powell

AtticusMars said:

Dan Powell said:

Even with more topology, haven't been able to improve the result much.

It may be a case of having to accept defeat, and making a non-contiguous mesh - will make the cage much simpler, but wastes UV space. 

I wish you'd have uploaded an obj/fbx because I would have liked to have been able to see this mesh since I'm a little confused as to how this would cause you to waste any UV space at all, you have hard edge splits everywhere so this mesh must be a decent number of UV islands already.

It hasn't been mentioned yet because it's bad practice, but I've had this problem before and I simply painted it out in photoshop. So if you need a last resort...

Hiya, and cheers for the post.  

Wastes UV space because the original, contiguous Mesh I've posted screenshots for, and scene files for, above, has less overall surface area than a mesh that was not contiguous. 

Just to clarify any confusion, contiguous is where the mesh is all attached together as one big object, and the topology all connects - whereas a non-contiguous mesh has lots of sub-objects than are not necessarily connected by topology.

I'll post an .obj file of the contiguous mesh that I linked above; in case you're not using 3DS Max.

The errors would be a bit of a pain to paint out (plus I really dislike doing it! ) because they're on the grooves of the object as opposed to being on a flat plane 

Link to FBX
https://www.dropbox.com/s/0sb4n8ozokq580x/DPowell_CCTV_Camera_LP.FBX?dl=0

Link to the 3DS Max file is above - contains the highpoly object as well 

ZacD

You might get away with just putting that one problem vertex in exactly the same place where the vertex is on the lowpoly, you'd have to try baking it to see if it would work.

AtticusMars

Why would you need to change the UV layout at all just to create a non-contiguous mesh? As long as you break your mesh apart at the UV island seams you should be able to leave the UVs as is.

Will check the FBX shortly

AtticusMars

I'm not sure what kind of topology you tried but I was able to fix this by adding more geometry as others have suggested.

(I didn't have your high poly so I built my own out of the low, and I had to recreate the UVs because Blender is trash at preserving them while editing mesh topology. But I kept the mesh contiguous, as you wanted.)

Cage on the bottom, it's very sloppy but it shows you that it is possible to deal with.

Otherwise, I didn't have time to try it but I still don't see any reason why you would have to change the UVs just to break the front piece off into a separate object. You've split every UV island at the hard edges like you should be doing, so just break off the front at its UV borders.

Dan Powell

Hey, sorry for the slow reply. Just a quick post of appreciation anyway!

Got it working. I tried both methods, and they both had a very similar result. Thanks a bunch all.