Stripes showing up in Iray render.

Sigurd

I just started having issue with stripes showing up while rendering in Iray. I double checked the model and it does not appear to be the problem. It inly appears when viewed from a certain angle. As I slowly rotate the object about the y-axis I can see the stripes slide along the surface and then disappear. So it does not appear to be a proble with the face itself as it moves back and forth. I have rebuilt the model faces and and it does not seem to be a problem there. Also I would expect it to show up at different angles if this were the case. Include are some pics of the stripe on my sculpt.

Any advice is appreciated.

 

P.S. I did submit a ticket to Daz I was just wondering if anyone on the boards would have some advice re this.

 

Thank you.

nonesuch00

Sure it's not shadows being cast from another nearby object that is not in render view?

Sigurd

I tried to attach pictures but it does not seem to be working.

I will try lower resolution pics in a minute.

 

barbult

Sigurd said:

I just started having issue with stripes showing up while rendering in Iray. I double checked the model and it does not appear to be the problem. It inly appears when viewed from a certain angle. As I slowly rotate the object about the y-axis I can see the stripes slide along the surface and then disappear. So it does not appear to be a proble with the face itself as it moves back and forth. I have rebuilt the model faces and and it does not seem to be a problem there. Also I would expect it to show up at different angles if this were the case. Include are some pics of the stripe on my sculpt.

Any advice is appreciated.

 

P.S. I did submit a ticket to Daz I was just wondering if anyone on the boards would have some advice re this.

 

Thank you.

I don't see any image attachments.

Sigurd

I am working on pics right now the other ones did not load. There is nothing else in the scene to be reflecting.

Sigurd

I cannot upload bmp. I will convert.

 

Sigurd

Here are a couple of pics in jpg.

 

barbult

Thanks, I see the image now. I have a few questions that might help us figure it out:

1. Are these full Iray renders to an image file, or are they Iray viewport preview? I've seen some issues where even a photoreal Iray viewport preview will have artifacts that the full Iray render does not.
2. How are you lighting the scene? Is it lit with an HDRI, the automatic headlamp, photometric lights, some combination, or something else? If you change lighting, does the problem change?
3. Are you rendering from the Perspective camera or have you added a rendering camera with Create>New Camera. (Create>New Camera is the better way.)
4. Is the model UV mapped and textured with an image map? Image compression of mapped textures can be an issue that causes artifacts.

Sigurd

1. These are Iray renders to library (control + R).

2. Currentlt Dome and scene. I have also tried sun-sky only.  I have tried a few different lighting solutions but no help.

3. I have tried default and create-new camera. Same results.

4. The model is UV mapped. I have tried uber and non-uber. I have tried image and no image plugged into the diffuse. I am doing the same things I have been doing for the last year and a half and I have never had these problems before.

It does not appear on 3delight.

I am almost done with this project and it is a little frustrating not knowing if this will be a problem for other users of this model.

Here is another pic. As you rotate model the stripe will appear on the receiver then reciver and magwell and then just the receiver again as the rotation continues.

 

barbult

Well, you've tried about everything! Here are a couple additional things to check. Beyond that, you've exceeded my capability to assist. I suggest that you submit a bug report, on the chance that Customer Service can help. You might also post an image here showing the wireframe  view of your model. Maybe another modeler will spot something.

Is your model at world center 0,0,0? There are some shadowing artifacts that appear if the model is moved a long distance from world center. http://www.daz3d.com/forums/discussion/63424/funky-eyelash-shadows-with-iray-aka-don-t-stray-from-world-center

There are also shadowing issues that can appear due to the construction of the mesh, or bump and normal maps. http://blog.irayrender.com/post/29042276644/shadow-acne-and-the-shadow-terminator. ; These can sometimes be improved by subdividing the model.

hphoenix

Sigurd said:

1. These are Iray renders to library (control + R).

2. Currentlt Dome and scene. I have also tried sun-sky only.  I have tried a few different lighting solutions but no help.

3. I have tried default and create-new camera. Same results.

4. The model is UV mapped. I have tried uber and non-uber. I have tried image and no image plugged into the diffuse. I am doing the same things I have been doing for the last year and a half and I have never had these problems before.

It does not appear on 3delight.

I am almost done with this project and it is a little frustrating not knowing if this will be a problem for other users of this model.

Here is another pic. As you rotate model the stripe will appear on the receiver then reciver and magwell and then just the receiver again as the rotation continues.

 

That sounds/looks like a normals issue.  You'd need to open up the OBJ file in a modelling program (like Blender) and check the normals of the faces around that area.  A single quad with the normals flipped could easily cause that kind of problem......

 

Richard Haseltine

Are you sure there is no excess geometry in there  -a doubled up edge, or a polygon going across the model internally? It loks like shading artefacts - what happens if you adjust the smoothing angle to 0 in the Surfaces pane?

Sigurd

Thank you all for helping. The artifiact suddenly showed up today on two different components. These same components were fine yesterday. The receiver artifact is on a single quad face (four vertices). I checked all four vertices to ensure that the face was coplanar. It was. I refreshed the UVs. DId not help. I deleted the face and relplaced it,  no help. The artifact only shows up in a fairly narrow range of rotation. Once it is showing, you can change the altitude and it does not change. Rotating causes it to disappear.  Also moving along the x axis causes it to disappear. It is darkest at x coordinate 0.0. It fades as it moves up or down the Cartesian plane.

I know modelers are loathe to think it is their sculpt that could be the problem, so I I quadruple checked it. When I remove the face it shows no artifact. I make a new face, only four points it isn't hard, and the artifact show up again. The fact that it shows up on the other component too is odd. I have made several iterations of the receiver yesterday so I am backtracking to see if it was in my earlier versions.

The artifact is on the backside of the model so I did not notice it immediately as I was working on the ejector.

Thank you all for your help again, if you think of something, let me know. If I find out what is up I will post.

 

Thank you again,

Sig.

Sigurd

The artifact happened between version 5.3 and 5.4. Looking to see what, if anything, changed on that side at that time.

Thank you again for taking time to help.

 

These pics art to show how far the artifact slides down the side.

Sigurd

You guys are great! Found a tiny quad on the border of the face that was causing the problem. I had been searching the face itself, not the adjoining faces. It was extremely small, I had to use max magnification on Blender to see it, but large enough to mess things up.

Thanks alot.

Richard Haseltine

I'm glad you were able to resolve it.

Sigurd

I found the problem, not totally resolved yet. I have it so the individual part looks good, but it still shows the defect when exported as the whole rifle. Currently working on this. I might have to go back to the iteration where it was ok, and try to determine where exactly it went off and whether that refinement is truly necessary.

It is frustrating to have it look fine, combine it with the rest and export it and have the problem show up.

It messes with my conception of reality.

Sigurd

Really need some help here guys.

I decided to re-engineer my receiver from scratch to eliminate problems.

I started with a cube primitive solid. Scaled it to length and height. Adjusted outside contours, still a solid. Added bolt and the problem was still there. I thought the problem might be with the bolt. took a cylinder primitive to represent the bolt, added to the solid cube-receiver and still had the problem.

Any particular reason why two merged solids could be causing this?

Is it possible that this is actually a rendering issue?

I am using a GTX 980 and have not had any problems before like this.

Here are the pics. The cylinder is just a primitive and the receiver is a primitive cube with exterior contouring only.

I am going to see if I get this same problem on my son's computer.

Please, any help is appreciated, this is really driving me nuts.

 

Thank you.

 

Richard Haseltine

it might help to show wire shaded views of your mesh, or even to upload a copy of the OBJ file if you are willing.

Sigurd

OK. Thanks. I will do what I can. Thank you for all your help.

Sigurd

Ok. I have been working on finishing the new receiver. Here is the  primitive model I was talking about.

When I set y axis at 195 while leaving everything else zeroed out the marks show up.It only shows up throughout a narrow margin of rotation. I do not see any reason why that should be happening to a primitive. If this had been my other model I could think of a dozen possible things that could cause odd renders. That is why I rebuilt. I started with a cube, scaled it to length and width. Then I added loop cuts for contour. At this point I took a cylinder primitve to represent the bolt to see if the issue would present itself. It did.

I tried to upload the obj file right now and it said files of that type are not allowed.

Here is the pic of the problem.

 

Richard Haseltine

Try putting the OBJ in a zip, or use a service like Dropbox.