topic Re: Arnold Renderer Bug? in 3ds Max Forum

Arnold Renderer Bug?

I_Megaman_i — Sun, 14 Jan 2024 07:17:52 GMT

why is it happening, Ive tried everything I know

its NOT a UV problem
I have tried creating new materials and new texture files, nothing
I think, it all started when I changed a color profile. Right now it is set to "Unmanaged"

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 03:52:10 GMT

Sure looks like a uv problem. I've had similar issues when I export FBX to Rizom UV and then back in, I've hard to start using obj instead. Are you *sure* it's not a UV problem? If you select those uv's (which are likely stacked or mirrored) and move the shells around, do they behave normally?

Best Regards,

Re: Arnold Renderer Bug?

I_Megaman_i — Wed, 17 Jan 2024 05:01:31 GMT

@I_Megaman_i wrote:

If this is not a new unknown UV bug, then yeah Im pretty sure its not the UVs. The asset in 3ds max is the same as in substance. Like I said it, it been just fine, the next moment its not. I havent changed the UVs when all this started.

Re: Arnold Renderer Bug?

CiroCardoso3v — Wed, 17 Jan 2024 07:04:53 GMT

Can I have a look at this file? Are you using smooth at rendering time?

Re: Arnold Renderer Bug?

I_Megaman_i — Wed, 17 Jan 2024 07:26:11 GMT

@CiroCardoso3v wrote:
Can I have a look at this file? Are you using smooth at rendering time?

sure.

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 09:06:30 GMT

I checked out your file, and I think I know what the problem is.

When you are going to bake the various mesh maps in Substance, it's having trouble with the overlapping uvs. You can *have* overlapping uvs, but the game convention is to offset them 1 unit to the right so that they are picked up by the tiling of the texture, but not by the map baker. (You can move them back after you setup the mesh maps if you want.) So, I think if you were to check out your baked source maps in substance, that your normal map and maybe some others have a weird glitch right there because it couldn't decide which side was up.

To fix it, just select overlapping shells and type 1 in the "U" value on the bottom of the unwrap window. This will offset your overlapping uvs so they are not seen by the map baker in substance. Screenshot attached of example. Substance really hates those uvs to overlap, but if you offset them it'll work like a charm.

Best Regards,

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 09:15:56 GMT

And as far as the render goes.... it looks good on my end when I press render, but I don't have your environment map.

I do see that materials are very dark in the material editor preview and color management seems to be off for the scene. I set it to Aces linear and it looks pretty good in the material editor then. If yours doesn't, it must be the environment map you are using. Perhaps it needs a colorspace override to Raw?

I also noticed you have exposure control on but you don't have any lights here or a camera so perhaps that might be related.

Best Regards,

Re: Arnold Renderer Bug?

I_Megaman_i — Wed, 17 Jan 2024 12:46:52 GMT

@Diffus3d wrote:
I checked out your file, and I think I know what the problem is.

When you are going to bake the various mesh maps in Substance, it's having trouble with the overlapping uvs. You can *have* overlapping uvs, but the game convention is to offset them 1 unit to the right so that they are picked up by the tiling of the texture, but not by the map baker. (You can move them back after you setup the mesh maps if you want.) So, I think if you were to check out your baked source maps in substance, that your normal map and maybe some others have a weird glitch right there because it couldn't decide which side was up.

To fix it, just select overlapping shells and type 1 in the "U" value on the bottom of the unwrap window. This will offset your overlapping uvs so they are not seen by the map baker in substance. Screenshot attached of example. Substance really hates those uvs to overlap, but if you offset them it'll work like a charm.

Best Regards,

I know about this trick, but thanks anyway, as you can see the normal map is perfectly fine😉

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 12:52:30 GMT

Well, I'm talking about the mesh maps not the texture maps. I don't have those. Anytime I've seen that issue it's because of overlapped uvs or a min/max value in the baker properties. Since it doesn't happen in 3dsmax, it's certainly coming from substance.

Best Regards,

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 12:57:11 GMT

Maybe set the max frontal and rear distance down on the texture baker since those planes are so close to one another in the 3d object. Best guess based on your feedback.

Best Regards,

Re: Arnold Renderer Bug?

I_Megaman_i — Wed, 17 Jan 2024 13:05:16 GMT

@Diffus3d wrote:
And as far as the render goes.... it looks good on my end when I press render, but I don't have your environment map.

I do see that materials are very dark in the material editor preview and color management seems to be off for the scene. I set it to Aces linear and it looks pretty good in the material editor then. If yours doesn't, it must be the environment map you are using. Perhaps it needs a colorspace override to Raw?

I also noticed you have exposure control on but you don't have any lights here or a camera so perhaps that might be related.

Best Regards,

1. I ve created a new scene, and merged in the asset separately, I,ve also removed an env map, so its just grey color. But render is still not showing what I want.

2. Color management must be set to "unmanaged" because the other materials in the scene are getting along with this option just fine or had been getting along before this happened🙄

Re: Arnold Renderer Bug?

I_Megaman_i — Wed, 17 Jan 2024 13:11:30 GMT

@Diffus3d wrote:
And as far as the render goes.... it looks good on my end when I press render, but I don't have your environment map.

I do see that materials are very dark in the material editor preview and color management seems to be off for the scene. I set it to Aces linear and it looks pretty good in the material editor then. If yours doesn't, it must be the environment map you are using. Perhaps it needs a colorspace override to Raw?

I also noticed you have exposure control on but you don't have any lights here or a camera so perhaps that might be related.

Best Regards,

if its okey on your end, then I have one more reason to suspect broken color management.

Re: Arnold Renderer Bug?

I_Megaman_i — Wed, 17 Jan 2024 13:16:24 GMT

@Diffus3d wrote:
Well, I'm talking about the mesh maps not the texture maps. I don't have those. Anytime I've seen that issue it's because of overlapped uvs or a min/max value in the baker properties. Since it doesn't happen in 3dsmax, it's certainly coming from substance.

Best Regards,

Check it out if you want.

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 21:08:01 GMT

I'll take a look. The render looked generally the same when set to unmanaged. It was just dark in the material editor. I'll make some screenshots.

Best Regards,

Re: Arnold Renderer Bug?

Diffus3d — Wed, 17 Jan 2024 22:29:15 GMT

The screenshot is tricky because it's showing the reflection on the bottom of the box like a glitch, but it's just how the geometry and materials work there. That's funny.

I made some screenshots:

Substance_iRay.png - I get the same render as your screenshot, but it's more clear what that weirdness is. Metalness in PBR basically means 'only receive light from reflections'. Direct light won't affect them. So the dark stripe reflected in your render is the bottom of the crossbar which is unable to get light on it. Which totally looks like a uv glitch, and I can see how you might have been frustrated hearing that when it isn't. I don't know if you consider this broken or not, but if you do the easy fix is to either make it less metallic, which just means 'accept light' with your current settings. If you go to your Reflector layer and start turning down metalness, you can see the problem basically fade away. Now, maybe you don't think it's a problem and then just ignore this.

In 3dsmax - So if color management is set to off and the render is not looking right, I guess I don't understand how color management is to blame. Maybe I am misunderstanding part of the problem. ok, some screenshots:

Open File and Render.png - You can see the normals are a bit wonky, but ignoring that, the colors are bright and not at all dark like your original screenshot. Now... you are using exposure control so when I turn that off I get a dark mess similar to your top image but darker. (No Exposure Control.png).

Hide Lids and Render.png - So I hide the lids and I can see the glass material is misbehaving. I also noticed there is no opacity map plugged in which means you're depending on the base color, and it's using png transparency. These are notoriously problematic with high end renderers because of differences between transparency and alpha. It can also be problematic in realtime stuff when what is behind the glass is attached to the same object as the glass. I digress... The problem is your texture map is set to interpret image alpha, which pngs don't have. (They have transparency.) So, maybe trying a different texture type for the albedo would help. Or as an alternative, use a mask or something that represents the transparency as alpha in the cutout opacity channel.

So as I test I isolate only the 'glass' parts and do a render. (Lids Only Alpha.png). That's weird... those are supposed to be transparent right? They aren't, at all. No wonder we can't see through them.

So I plug the base color map into the opacity cutout channel just to see if it'll be transparent, and it does go transparent. (I know that's not the right map, it's just a test.) (test opacity.png.) Ok, now things work right.

So, the problem is your material setup and texture format for the glass. Try an image format that uses alpha instead of transparency if you have an object behind it that's part of the same mesh, and use the cutout opacity channel if needed. TGA's work well for this or a black and white mask image for the cutout opacity.

At least, that's how I'm reading this. Since plugging anything into opacity makes the glass suddenly see through, that's where I'd begin.

Best Regards,

Re: Arnold Renderer Bug?

I_Megaman_i — Thu, 18 Jan 2024 04:18:32 GMT

So I plug the base color map into the opacity cutout channel just to see if it'll be transparent, and it does go transparent. (I know that's not the right map, it's just a test.) (test opacity.png.) Ok, now things work right. So, the problem is your material setup and texture format for the glass. Try an image format that uses alpha instead of transparency if you have an object behind it that's part of the same mesh, and use the cutout opacity channel if needed. TGA's work well for this or a black and white mask image for the cutout opacity.

Substance_iRay.png - I get the same render as your screenshot, but it's more clear what that weirdness is. Metalness in PBR basically means 'only receive light from reflections'. Direct light won't affect them. So the dark stripe reflected in your render is the bottom of the crossbar which is unable to get light on it. Which totally looks like a uv glitch, and I can see how you might have been frustrated hearing that when it isn't. I don't know if you consider this broken or not, but if you do the easy fix is to either make it less metallic, which just means 'accept light' with your current settings. If you go to your Reflector layer and start turning down metalness, you can see the problem basically fade away. Now, maybe you don't think it's a problem and then just ignore this.

Did you find anything wrong with the UVs? Can Opacity and Metallic maps be the reason why Arnold renders it incorrectly? Then why the rest of the materials are totally fine(see MESSAGE 11 OF 15), which have been arranged and configured using the same workflow? Would you explain THAT weirdness?

In 3dsmax - So if color management is set to off and the render is not looking right, I guess I don't understand how color management is to blame. Maybe I am misunderstanding part of the problem. ok, some screenshots:

Because you are expecting it to work correctly like I do. What I have in 3ds max viewport render is what I should get in Arnold render as well.

Re: Arnold Renderer Bug?

I_Megaman_i — Thu, 18 Jan 2024 06:49:08 GMT

Just for the sake of experiment, this is a scanline rendering. As you can see there are no dark textures and no artifacts. Another reason to believe my UVs are super fine and theres something wrong with Arnold:-)

1:) viewport - fine

2:) scanline - fine

3:) SP - super fine

4) UVs - extremely fine:-)

5) what else?

Re: Arnold Renderer Bug?

Diffus3d — Thu, 18 Jan 2024 08:51:33 GMT

In my opinion it's rendering correctly, but the materials are setup incorrectly. I don't necessarily agree with some of the conclusions here but I'm no arnold wizard. Maybe the other objects which seem fine are rendering correctly because they aren't behind glass? I have no way of really knowing. Maybe one of your substance layers has alpha checked and is overriding the proper alpha on the glass and that didn't happen on other objects. Could be anything really.

Sometimes transparency just doesn't cut it. If you save just the color map out as a tga instead of a png, that should solve the problem. Or, using a map in the opacity channel fixed the problem on my end. Easy fix. Use any method to get alpha instead of transparency.

I didn't see a problem with the uvs, the substance screenshot just looked strange to me, similar to a uv problem I've encountered in the past. But that's not it in your case. My opinion is just that that back face is too metal. Reducing the metal a little would allow it to get ambient light which makes the reflection less harsh, but that's a personal taste thing not a technical thing. There doesn't appear to be anything wrong with the model or uvs, but looking down into that thing when the base is totally metal produces a strange look. Just my opinion and no offense intended.

Best Regards,

Re: Arnold Renderer Bug?

I_Megaman_i — Thu, 18 Jan 2024 09:07:16 GMT

Can I send you the whole scene via PM?

Re: Arnold Renderer Bug?

Diffus3d — Thu, 18 Jan 2024 09:14:10 GMT

I want you to be happy, and if that helps... sure. What is the issue that needs to be solved though? You don't like the idea of using a different texture type or the opacity slot? Or did it not work when you tried it? Just let me know what I'm looking for and I'll do my best.

Best Regards,