VRayDisplacementMod across multiple Objects

[Art48]

Hi,

I got the following situation:
I have a part of a wooden parquet floor of approximately 20 planks total, each one modeled by hand, simple geometry (chamfered box).
I have a displacement map of a company Logo (too difficult shapes to model by hand)

Because of various reasons I cannot substitute the modelled planks by a plane with a texture.
I need to emboss the company logo across the planks, meaning imprinting it, displacing geometry downwards into the floor/planks.

So what I did was select the planks which the logo will be covering, apply one DIspMod across them all and set it up just as I would set it up when doing it on a plane or something simple like that.

Now the problem: It kinda works.
Firstly the rendertimes skyrocket compared to the plane approach (maybe factor 30-50?) But only until the geo is there and the rendering itself starts, then the speed is normal.
Secondly I get artifacts at the gaps between the modelled planks. The geo at the gaps doesnt get transformed down, but kinda remains at the floor level giving strange results.

Anyone know how to prevent that from happening? Or any other workflows for embossing/imprinting something across multiple meshes with gaps inbetween?

[vlado]

Maybe use the texture as vector displacement texture in object space so that the displacement is always down, rather than along the surface normal. In that case, you might have to make the red and blue channels of the texture black, or something like that - I need to try it to be sure.

Best regards,
Vlado

[Art48]

Hi,

Thanks for that info, I've tried the Vector Displacement now, with the following results:

The issue with the gaps is gone now and works as expected while the rendertimes also reverted to more or less the same as with the plane displace approach.
The displacement texture is an 8 bit TIF loaded with the bitmap loader of max.

A new issue appeared:

[vlado]

Turn on the "static geometry" option and see if it helps.

Best regards,
Vlado

[Art48]

Worked perfectly, plus decreased rendertimes. Awesome. May I ask why exactly this works so well and the checkbox off gives so strange results?

[vlado]

The "static geometry" option causes V-Ray to pre-tesselate the displaced geometry in advance and then render it as regular geometry. Otherwise V-Ray generates it on the fly while rendering and it seems like the flat surfaces cause some kind of intersection errors. To be honest I'm not sure exactly why the artifacts are there and I would very much like to take a look at the scene if possible to send it to vlado@chaosgroup.com

Best regards,
Vlado

[Art48]

Alright, the RAM consumption is horrendous, though .
Will send you a mail with the link to the file. Please let me know if you can find the issue so I may avoid it until a fix is there.

[Art48]

Just sent you the correct FTP link. Sorry.

[vlado]

Alright, the RAM consumption is horrendous, though

Well, there's pro's and con's to everything Especially in rendering, it's either more speed or low memory usage, but rarely both.

Best regards,
Vlado

[Morbid Angel]

also when using vector you might need to set the clip boundary to be anything other then 0 typically -1/1 if its a float map you are using.

[Art48]

Thanks, but it's just a plain 8bit TIF here, sufficient for my case.