MultiTile Map does not support gamma Override?

[10DSpace]

Normally, when you load bitmaps into a material slot (whether it be a standard material or Vray Material), and choose the gamma override option set to 1.0 (as you need to do for normal maps or glossiness maps in a PBR workflow), max dutifully "remembers" the gamma override set to 1.0 that you set when loading the map into the slot.   Specifically, if you open the bitmap in the material slot  again, the gamma override setting = 1.0 is shown in "Select Bitmap Image File" dialogue. 

However, if you put a MultiTile Map into any material slot (as you would do in a UDIM workflow)  and then attempt to load a bitmap with the gamma Override set to 1.0  Max will not remember the gamma Override setting of 1.0.   Specifically, if you open the bitmap you just put in the material's MultiTile slot again, the gamma override setting is lost and the gamma setting shows as "automatic."

This is a big problem for using the MultiTile Map because certain maps need to be set to a gamma override = 1.0 (eg., Normal, Bump, Vray Reflection Glossiness & Reflection IOR in a PBR workflow).  So I don't see how the MultiTile Map is even usable.   

 I confirmed this behavior in bothe max 2017 & 2019 by following the steps I describe in the first 2 paragraphs.  Am I missing something or is this a serious bug with the MultiTile Map? 

[hagen.deloss]

Hi @10DSpace 

Thanks fro bringing this issue to the forums! I'm looking into this behavior, and will give a more thorough updated when I have more information. I can tell you right now that in 3ds Max 2020.2 I am experiencing something similar when I test this, here is a gif (is this the same as on your machine?).

I was able to find some more insight regarding UDIM workflow from this forum post, and also found a potential naming convention issue with UDIM multi-tiles that I will follow up with Brent regarding this next week.

I will be looking into this more, talk to ya soon 😄 

[10DSpace]

Thanks for looking into this.  Regarding your question, no the Invalid File format error you are getting is not my issue.  That is the naming issue.  You are trying to load an image "Image001.png" into the multi-tile slot with UDIM selected as the File Pattern Format.  I am using the correct naming convention for recent versions of max (i.e., image_diffuse-1001.png  or image_reflection-1001.png   etc, and so I get no error message.   

My issue is that after loading a correctly named map into the multitile map slot with gamma override selected, the map loads into the slot (with no error message), but I don't think that the gamma override is actually working because if you click on the bitmap slot again which triggers the same "Select Bitmap Image File" dialogue, max no longer remembers tghat this bitmap should be loaded with a gamma override.  For any other type of material (non_Multi-tile) map slot, (e.g., diffuse, reflection, glossiness, normal etc ) max always correctly remembers what ever you last loaded the map as in terms of gamma override or automatic.   This makes me think that gamma override does not work in the multi-tile map.  Please let me know if this is still not clear. Thanks for your help.

[hagen.deloss]

Hi @10DSpace 

Ahh, I think I get it now. Does the image appear incorrectly, or is the main indicator that the actual gamma override toggle (pictured below) doesn't remain checked after double-clicking on the MultiTile image slot?

I'm curious, does this happen with different file types? I have heard that using either .tga or .tiff is preferred when loading images with specific gamma settings. 

I will log this so it can be looked at 😄 

[10DSpace]

@hagen.deloss  Thanks for your continued help on this.

The image does not appear correctly either, although admittedly, the differences  can be subtle depending on the lighting.  However, one thing that is not subtle at all is the difference between the diffuse channel with a gamma setting of automatic vs gamma override = 1.  Please note that I am well aware that the diffuse map is best left to "automatic" and should not normally be set to gamma override = 1 in a linear workflow.  But for the purposes of determining whether the gamma override setting is working at all on a multi-tile map in the diffuse channel, try changing the gamma override setting back and forth between the 2 states.  There should be an obvious difference in both the viewport and the rendering and for every other map type I have used (i.,e bitmap loaded directly in the diffuse slot or any other slot, the VrayHDRI map type,etc), there is.  However, for the Multi-Tile Map type there is no difference at all when toggling the gamma override state.  My best guess is that the Multi-Tile Map is stuck on a gamma override setting of automatic and simply doesn't recognize any attempts to change to Override = 1.0.    I tried through scripting as well to change the setting (using the openBitmap function with gamma: 1.0, but it had no effect.  No errors in the Listener window, but no effect either).

Lastly, I did check to see if .tiff or .tga file types were treated any differently than .png, but they had no effect; I observed exactly the same pesky behavior.   Please advise if you learn anything about this from your tech gurus as I would like to be able to use the Multi-Tile map type but cannot at present due to these issues.  I am aware from a separate thread on the forum that the VrayHDRI map type is an alternative and I can confirm that it works perfectly with regard to the gamma settings (it has a specific field for it in the map dialogue).  A downside to the VRayHDRI map type is that I cannot get it to display properly in the viewport

Thanks.

[hagen.deloss]

@10DSpace 

Really appreciate the additional info. I would say that the OSL bitmap lookup node could work as it also has a UDIM Compatible Lookup checkbox, but also hear this doesn't preview in viewport.

I haven't heard anything from development yet, I will send someone an email following up to confirm this as an issue right now. 

[10DSpace]

@hagen.deloss 

Has anyone responded to your follow up? 

[hagen.deloss]

Hi @10DSpace 

Thanks for following up with this! I was talking with @giuseppe.schiralli  and he mentioned that the

OSL Bitmap Lookup node handles the Gamma value correctly, but lacks visual feedback in the viewport.

Let me know if this helps!

[10DSpace]

@hagen.deloss 

Thanks, you had mentioned OSL in a previous post and I am aware that it is another alternative to the VrayHDRI map which also correctly handles gamma, but neither of these solutions correctly display in the viewport. 

Are you confirming that your programmers acknowledge that the MultiTile map does not correctly allow setting the gamma override?  That has been my question all along.   I do think this would be useful information for the forum, particularly those using PBR materials with UDIMs.