Incorrect Viewport preview

[fraggle]

Hi, just find out that the preview is not really working with Vrayscan.
Viewport display didn't match the rendering.
Will be good to correct it, because it need a lot of render test to find the right UV scale.

Especially because the real scale looks very strange, unless the leather scan was done on 1x1cm! On this model done in cm (the poof seat is 102cm x 50cm), the real scale have to be set to 1cm to get a realistic pattern. This value are not very intuitive.
Also, I notice that once one vrayscan mat is into the scene, all other new vrayscan launch wih the same real scale as the one already in the scene (I test with 2 fabric and 3 leather they lauched all with a real scale of 1cm. A new mat is create everytime, I don't duplicate the one already in the scene).
Are the library not build with an embedded scale that match the size of the scanned material?

[Ivaylo Katev]

I will test it after a minute, just to mention that the usual pipeline is not to set the uw generator in "use real world scale" mode, i found there was some problem with it, but can't remember what exactly
use the "adjust UV tilling to an object" tool instead, put the uv generator in the default tilling mode, and activate the tool, pick the object and this is all that you need.

[fraggle]

Seems that I need more than just adjust UV tilling to an object.
So the mesh need an get an UV first? I just delete all of them, never trust a coder!

[Ivaylo Katev]

I found the reason - the preview really is not matching the render, when triplanar is used, thanks for the report, will be fixed.
Few words about the uv generator tiling factor and how it works with the triplanar option. As i said above, the "use real world scale" of the uv generator is useless, it just shows inverse values of the tiling factor in the UI, for example if the tiling is 5, it shows 0.2.
This is a bit misleading, because you see in the info of the material "size: 5 x 3 cm " and it's pretty normal to think "how cool, i will put this value in the UV generator and wil select "use real world scale" and will have the perfect scale. Well, putting 5 and 3 in the "size" fields of the uv generator is totaly equal to putting 0.2 and 0.3333 in the tiling fields, when "use real scale" is not enabled. The uv generator does not know the size of the geometry and can't include it in the calculations, so it works as if the UV units are scene units, that is not true in the most cases.
If you are not using triplanar, the proper way is to pick the object with the "adjust UV tilling" tool.
If you use the triplanar value, the tilling factor is interpretted as multiplier to the correct tilling factor, i.e. for proper scale it must be 1 (that's why you get correct result with size 1) , if you use the adjust UV tool with triplanar, the result will be wrong (warning message will be appropriate).

[fraggle]

This workflow is definitively not the right one, unless I didn't follow exactly your advice.
- Uncheck the real scale in the mat
- Clear all UVmap of the object
- Use triplanar in the mat
- Auto detect tilling-> click on each object one after each other

Thanks

[Ivaylo Katev]

No, it's not this. There are two different approaches:
- Use the uv mapping of the object and the uv adjustment tool, that just calculates for you the correct uv scale of the object mapping, and puts it in the tilling fileds. Note that the UV scale may be different for each geometry, for example two simple cubes with different size, in this case you need two material instances, each with its own tiling values
OR (they are mutualy exclusive)
- Use the triplanar mapping (the object own mapping is ignored). The triplanar mapping works even if you have no uv map in the object. In this case you have to put 1 in both the tiling fields, if you have tweaked them before. Because the triplanar ignores the uv mapping of the object, you can use single material instance for all the scene objects, regardless of their scale
Using the uv adjustment tool AND triplanar leads to wrong results, and after our conversation i decided to disable it.

[Ivaylo Katev]

some update: apparently the max viewport preview is always using the geometry uv mapping that makes the correct preview of triplanar mapping impossible, so only warning sign will be added

[fraggle]

For the leather, in fact a tilling of 3 is what, from a human eyes of view, make sense when you start to make a close up view. 1 is really to big (can be ok for far away render, but look unrealistic in close up render)

[Ivaylo Katev]

you mean with triplanar?

[fraggle]

Yes, triplanar, lot faster if you don't have time or don't like, to go unwrapped!

[Ivaylo Katev]

May be we have to turn it on by default, apparently big part of the users prefer to use triplanar instead the explicit mapping, despite the bigger control that the explicit mappoing gives