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Gary Dave

Why so many normal map options?

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I've been doing a bunch of tests with 3dc's 7 options for normal maps in the preferences panel, 5 of which are drop-downs that lead to even more options.

But, so far I've only been able to get two results, which I'm assuming is just the flipping of the green channel, which is pretty common.

My question is, why are there so many options here? If I change the preset to Unity, and the Tangent Space standard to Unity Space, that doesn't necessarily mean it will work in unity. It only works in unity if you also change the Export to "Maya, Blender". because if you set it to "3ds-Max, LW" it inverts the green channel. Which also raises the question "why isn't "unity" an option in the export?" Or better yet, stop making it software specific and just go the route of +Y/green or -Y/green, etc.

Swap TB seems to flip the sculpted details, but not the baked ones. This confuses me greatly.
Denormalized TB only seems to affect the auto-padding that exists outside of the UV islands, which has no use.

A lot of these options seem to have absolutely no effect on the normal map itself. I understand that some of them are referring to how the normal map is calculated inside 3dc, which will obviously have no effect on an exported map, but I'm just wondering why all of this is setup in this way? It makes trying to explain it to others near-impossible. It also makes problem solving a bit of a pain if your normal map hasn't come out right, because it seems as though you'd have to trawl through 30 odd options to find the right combo, when in actuality all you probably need to change is the export drop-down.

Edited by Gary Dave
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Your request was forwarded to developers.

27 minutes ago, Robert N said:

Okay I see and here are a few hints:

Green channel (some background information)
Just read that Modo by default interprets normal maps in the OpenGL way instead of the DirectX way and these two interpret the green channel contrary (because the y axis in UV space is inverted).
So inverting the green channel in Modo is one option - thanks for the hint!
The other option is to invert the green channel when exporting from within 3D-Coat. This can be done by setting the "Normal Maps Export" in the Preferences to "Maya, Blender".

So "Maya, Blender" corresponds to the "OpenGL" way normal map
and "3DS-Max, LW" seems to be like a "DirectX" normal map

By the way I have to agree with Gary (https://3dcoat.com/forum/index.php?/topic/20056-why-so-many-normal-map-options/ ) stating that the option to invert the green channel in 3D-Coat might be more accessible with a separate checkbox (or by naming the dropdown options like "OpenGL" and "DirectX") instead of binding the preference to Software names. The software specific stuff should only be saved in within the chosen options of the "Normal Map Sofware Presets".

Padding
Unchecking "Denormalized TB" seems to create a padding once, which had a positive effect here (though does not completely solve the issue).
Also make sure "Create Padding" is checked in the export dialog.

... more tips and hints on a smoother normal map exchange are very welcome! 
 

 

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All that options for tangent space are same on usual meshes. Difference begins when you have some special features on the mesh. For example, stretched UV-s, different UV scale on neighbor faces, sharp edge smoothed with normalmap. Difference well visible if you thy to bake high-poly object with flat face over very low-poly mesh. Say, very highpoly cube over lowpoly. All presets was done 3-4 years ago, so (possibly) method in Unity changed since that time.

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@Gary Dave Presets are not only about the normal map, even if they are called Normal Map preset.

They are a bunch of settings included in XML files to tell how 3DCoat is going to export. You can go to ToolsPresets\ExtTools in the 3DCoat folder where you installed it and then see the differences in the files.

When you choose a preset, then changing settings doesn't matter, the preset settings override the export settings that are on preferences. So things may change from one preset to another even if the exported normal map type is the same,  because Triangulation method, Normals Calculation Method or the Tangent space may be different from one preset to another and these three settings are included in every preset, plus some presets have settings set for Swap TB and Denormalized TB, which changes things too.

Of course, this is something that can be only checked when opening the XML files. So the only way to have complete control over what you export and how you do it is to choose unknown and set the settings the way you want.

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