Unwanted visible seam has me perplexed!

[shawn]

In building an animation about the functions of an inkjet printhead I need to have a portion of it split apart to get into some of the inner detail, so I've created a nozzle plate that's two parts, with the foreground part being built from a copy of the main part. They both use the exact same material and settings, but I'm getting a visible seam between the two, and I cannot figure out what's causing it. I want it to be seamless before they separate.

The nozzle plate is semi transparent. If I take the transmission down to 0 the seam doesn't appear, but once I get the transmission cranked up to around .20 the seam becomes evident.

Both objects have Parameter Tags with Opaque unchecked. If I check Opaque they become opaque and the seam disappears.

If I turn off Shadows in the Parameter Tags, or deactivate shadows in the Arnold Sky object, the seam disappears (in the transparent objects). So it's some kind of shadow artifact?

Am I missing a setting somewhere?

I've attached a very simplified scene file.

Thanks.

Shawn Marshall

visibleseamc4d.zip

[lee_griggs]

They are two separate objects. Combining them fixes it.

[shawn]

Thanks for the reply.

As I wrote in my original post, the point of the animation is to have the front part move away from the back part so I can fly the camera into some detail (that's not included in this sample frame or scene).

So making it one object would kinda defeat the purpose.

Cheers.

Shawn

[lee_griggs]

Fair enough. Seeing as it is a modeling issue, I would create new planes and add circular ramps -> opacity.

[shawn]

Thanks again for taking the time for the reply.

As this is more of a graphical, rather than photorealistic, animation I can get away with just deactivating the shadows on those objects, which make the seams disappear.

I guess my hope was that rather than concoct a workaround I could get some insight as to what would cause such an artifact. The two parts line up perfectly (I snapped their vertices). So what's causing this artifact ONLY when shadows are active?

Cheers.

Shawn

[lee_griggs]

Strange, the normals look correct. I exported it as an .fbx into Maya and it renders fine.

[shawn]

Thanks for taking the time to check into it; I appreciate it.

Perhaps it's a bug or something.

Cheers.

Shawn

[peter.horvath6V6K3]

I noticed that the 'Receive shadows' flag of the shapes is turned off while the 'Self shadows' flag is on. This means that the plate casts shadows on itself, but does not receive shadows from the other plate, which is causing the seam where the two plates connect.

[shawn]

Thanks for replying, Peter. I guess I didn't try that combination of settings.

Best.

Shawn