matte shadow & reflections/refractions - huge problem

[flipside]

Ok, I'm still trying to get good results for the blochi scene. Everything is ok, except that the tabletop should be reflective, and this seems to be not so evident.

The tabletop is a matte shadow material (vraymtlwrapper) with a vraymat in it, which has the bg image in its diffuse slot (tabletop camera mapped).

Here's the render without reflections:
This is not good, because the table IS reflective (see coffeecup and window reflections all over the table)




Here's the image with the material reflective:
You can see this is wrong... It also reflects the surrounding hdri, which is not needed because actually the table in the pic already reflects this environment.




So I go to tabletop mat and I set a black pic in the environment slot of the material. This way, I can make sure the table will not reflect the environment (it will reflect 'black')
This is the result:
It looks good, except in the relfections of the sphere and especially in the refractions of the glass plate.




It becomes more visible when I turn up the reflection amount:






I'm out of ideas, so if anyone has suggestions, please let me know!

[GoncaloP]

I also had that problem, dont know how to solve it thought...

Gonçalo

[Da_elf]

have you tried setting the background image as your reflection override on the tabletop using screen mapping?

[flipside]

Here's what I get when I use the backdrop image as a screen map in the tabletop material environment slot:
(da elf, was this what you meant?)

[Da_elf]

yeah. that was my idea. but i guess it didnt work huh

[flipside]

This seems to be a problem in many renderers, but a guy with brazil was able to do it (don't know how).

here's his post:
http://hdri.cgtechniques.com/~blochi...6d239bf617b5cf

If Brazil is able to do it, Vray definately should! This blochi scene is there to test renderers limits, and I don't want this to be vrays limit...

flipside

[metroberlin]

i´m not sure how to use the matte material the right way. i just want to use the shadows and the reflections, not the whole table. but everytime he stores the whole table as the alpha channel. did i something wrong or did i understand something the wrong way ? is it even possible to get just the shadows/reflections and the rest is cut out

[metroberlin]

@flipside..how did you get just the sphere with the glossy reflections in the picture

[flipside]

I explained it in the first post.

The tabletop is a matte shadow material (vraymtlwrapper) with a vraymat in it, which has the bg image (=backdrop image, not spherical hdri) in its diffuse slot. The tabletop has a camera map modifier (this does the same actually as screen mapping for your map, but with the camera map I can move the camera and the texture on the tabletop will stay fixed as in the first frame - but ignore this if you just want a still image)

For the matte shadow options turn on shadows.

If you make the vraymtl a bit reflective (glossy), then you see the reflections in the tabletop. If you do not want the spherical hdri environment (which is in the vray reflect/refract override slot in globals) to reflect in the tabletop, put a black map in the vraymtl environment slot. But this gives problems in relfections and refractions, which was the reason for posting this thread.

hope this helps you

flipside

[metroberlin]

*bang the head*...now its clear. just one question left, concerning the moving boxes. i wrote you a pm. thanks you

[flipside]

I don't see any pm

[zager]

1 year later

I put a black map in the vraymtl environment and the Reflection total disappear. Am I wrong?

[roppin]

flipside. Is there any chance one cud get the file and background to try out?
/Daniel

[flipside]

If you put a black map in the environment slot of the material, it will reflect black so it looks like it doens't reflect anything. Although the material should still reflect other objects of the surroundings (actual geometry).

I'll have a look for the files, but I got them from the official site:
http://www.blochi.com/gfx/hdri/

These are the same maps etc that I have.

[zager]

I understand, but there is Reflection here

I can't that achieve.