Mapping problem between viewport and render

[Snork Maiden]

Hello everyone,

My students are having some issues that I can't figure out. At least 10 - 15 of them (out of 80) are having a weird issue with the mapping. They are applying mapping to each object through the objects properties and it's looking great in the viewport, however it then renders out differently to what they are seeing. Also no amount of changing the mapping properties can change the mapping in the render. Also, this is only happening on a few objects in their scene not all. And the problem is happening on all different types of projection modes. I've made sure that the objects don't have any coplanar surfaces, and only have one channel. I've have had a look at the widgets, and have tried altering every option in the mapping dialog box. I've also tried re-drawing the objects in question, deleting and replacing the material, deleting and replacing with another material. Every time the changes are shown perfectly in the render viewport but not in the actual render.


Here is one of the more obvious examples. In many of the files it's as simple as a texture being stretched in the render, but looking ok in the viewport and again nothing will change it. In this one no matter what we did the texture is lost in the render. Note that only the fence is being affected, everything else is ok.



I think this is the same issue as was discussed but never resolved here..

http://asgvis.com/index.php?option=c...17374#msg17374

any help would be greatly appreciated!

[the_master]

Re: Mapping problem between viewport and render

hmm form what i can see, then I will mean that you maybe have some problems with you Hardware, or the installation process or maybe something with your drivers.. , because it look like that kind of problem..

[Micha_cg]

Re: Mapping problem between viewport and render

Could you show a screenshot of the texture user interface of the material?

If viewport and renderings looks different, than a regular reason could be, that the texture mapping is wrong set at the material. Never I have seen this problem at my computer here.

[Snork Maiden]

Re: Mapping problem between viewport and render

I can't put a screen grab up because it's a students file and class is over, however, the materials U & V repeats are at 1 and offset is 0. All other settings are normal, multiplier =1, it's a texture and explicit.

Also this problem happens regardless of what material is applied, even materials that are working on other surfaces in the scene.

[Micha_cg]

Re: Mapping problem between viewport and render

So, it seems to be an object related problem. If you like, send me a file and I will test it - e-post at simulacrum de

[blastered_cg]

Re: Mapping problem between viewport and render

i saw that problem lots of times. it happens when you assign a mapping widget and change the UVW repeat values. try to set these values to 1 and chnage the widgets size.

[Snork Maiden]

Re: Mapping problem between viewport and render

thank you so much for the offer Micha - I'll see if I can get the file off the student before next class.

in the mean time i'll ask them to try changing the size of the widget instead of the UV repeat. If that is the problem though, why can't you use the UV repeat? What is it there for?

[dalomar_cg]

Re: Mapping problem between viewport and render

You can use the uv repeat, its just that going back and forth between adjust mappings and UV values can be confusing.

UV repeat takes a given texture space (from 0 to 1) and telling the image to repeat multiple times within that span. By default, adding a texture will use the default UV space of the surface which is generated by its base structure. In some cases adjusting the UV repeat values may be a good way to set your mapping. However once you start creating a actual projection type (planar, box, spherical...) then the repeat will be generated from the start of the mapping widget to the end of the mapping widget. Most people don't leave the mapping widget the same size, so the repeats will be happen with a smaller texture space, and then look weird and crazy like you posted.

My advice would be to set UV repeats via Rhino's mapping tools as opposed the the V-Ray options. Setting them there will allow for more visual feedback of the mapping, since Vray repeats will not be visual in viewport...only in the rendering

[Snork Maiden]

Re: Mapping problem between viewport and render

Sorry I think I confused you Dolmar!

The students have only been changing the mapping through the Rhino mapping options. All their materials have a UV repeat of 1. What I meant to ask is if blastered is correct and this error happens when someone uses the UVW Repeat in the rhino options (I left off the W in my reply hence the confusion) and it is corrected when you set that to 1 and then use the size of the widget to dictate the repeat of the material, why that is?

Surely VRay can use the UVW repeat option in rhino mapping as other objects in the same students scenes uses this process!

Does that make sense?