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Problem with material
Posted: Mon Feb 18, 2008 1:44 pm
by turbo2000
Hi, has anyone tried this material?
http://mxmgallery.maxwellrender.com/sea ... gh_Wall_01
My render won't start when i use this in my scene
I was thinking if it could have anything with the displacement map to do?
Posted: Mon Feb 18, 2008 1:53 pm
by def4d
have you tried the advices given in the comment?
Posted: Mon Feb 18, 2008 2:17 pm
by turbo2000
yes i have but it's still the same

Posted: Mon Feb 18, 2008 3:15 pm
by Mihai
Are you using adaptive precision? Try with a smaller height and less precision.
Posted: Mon Feb 18, 2008 3:49 pm
by turbo2000
Mihai > Yes i am using adaptive precision, smoothing off and an absoulte height of 1 cm and 0 in offset
Posted: Mon Feb 18, 2008 4:00 pm
by tom
Then, it means your base mesh doesn't have a reasonable amount of initial subdivision.
Posted: Mon Feb 18, 2008 4:03 pm
by turbo2000
Hmm.. how can i fix that? It's just an archicad/wall model i have exported and applied the material to it?
Posted: Mon Feb 18, 2008 4:21 pm
by polynurb
Hi turbo,
I think absolute height of 1 cm is far to much for this material;
It is supposed to simulate a type of limed rough surface, so in reality
that structure won`t be higher that ~ 1-2 mm.
With increased heigth you increase the amount of additional data to be calculated during displacement.
You could try to reduce the texture resolution/tiling (as I understand, adaptive creates "triangles" when two pixels differ in value) or change the mesh subdivisions
as tom said if you need adaptive; otherwise turn it off and tweak precision yourself.
cheers,
polynurb
Posted: Mon Feb 18, 2008 5:56 pm
by polynurb
*just wanted to add, that this is not supposed to be an archviz material for huge surface areas (displacement overkill). It should only be applied to the piece of wall that you get really close with the camera.
To give an idea what detail
can be achieved using the provided texture
look at this image (adaptive heigth/absolute 0,2 cm/ FD of 2,5cm/ single emitter plane/ SL10.5) :
now putting that kind of adaptive precision over an entire room, it will and can
never render. (and you can`t see the detail from far away anyway)
Propably it was a little misleading that i tagged it "architectural" as it has a little experimental character.
/ polynurb
Posted: Mon Feb 18, 2008 6:29 pm
by turbo2000
okay i WAS going to use it on a whole building, it looked very close to the real wall.
Btw, is it stupid to use displacment on large surfaces, like exterior walls?

Posted: Mon Feb 18, 2008 6:57 pm
by tom
turbo2000 wrote:Btw, is it stupid to use displacment on large surfaces, like exterior walls?
As long as you subdivide your walls first, it's not a problem.
Posted: Mon Feb 18, 2008 7:16 pm
by polynurb
turbo2000 wrote:
Btw, is it stupid to use displacment on large surfaces, like exterior walls?
*synchronous post
no, not at all,.. it just depends on the situation;
But I myself have not tested displacement on large surfaces a lot, but there are for sure applications where Displ. tops modelling speed&quality wise.
threre are many examples in the gallery:
Bubbaloo, for example used displacement on the fireplace wall in the 3dAllusions challenge, which would be an awfull lot of work to model by hand.... and it looks good with displ.
btw. try using low resolution textures for adaptive displacement first, and only increase resolution when you are not satisfied with the detail it gives you.
/same texture / same settings / downsampled from 2048 to 512 / Benchmark almost tripled:

Posted: Mon Feb 18, 2008 7:23 pm
by Polyxo
tom wrote:turbo2000 wrote:Btw, is it stupid to use displacment on large surfaces, like exterior walls?
As long as you subdivide your walls first, it's not a problem.
Tom,
Maxwell displacement is supposed to work mesh density independant. However, there's quite a few examples, which got posted lately which show, that the underlying mesh and its flow are obviously not irrelevant at all...
This feature seems to work flawlessly with the regular quad-meshes found in host programs which work with Subdivison Surfaces.
In Nurbs programs, where meshes are only a display aid, or in Sketchup which does not care about mesh-flow as all faces it produces are planar things seem to be different....
Could you give use some general advice for efficient work with displacement inside of programs which use a less regular mesh-structure than found inside 3DSMax or Cinema4D?
Thank you,
Holger
Posted: Mon Feb 18, 2008 7:23 pm
by Maximus3D
As Tom said

but keep in mind to have your displacement textures both tileable and at high resolutions to avoid repeating patters appearing on your walls, and seamless tiling to avoid weirdness at corners.
polynurb: Your first wall example looks good

i like that one.
/ Max
Posted: Mon Feb 18, 2008 7:39 pm
by polynurb
thnx Max!
I just wanted to illustrate that when the camera would be as far away as on the Photograph Turbo posted, it might actually look similar to the first render.
@polyxo: I don`t know what software you use; I use rhino, and for using displacement, the "custom render mesh option" is a must. I
never only use the global tesselation settings for the objects to be displaced.
the mesher options allow me to create a perfect quad mesh structure...
but as we arrived at this point ... I must assume that everything would be a very differtent story if Maxwell could
render nurbs directly.
I know it is a big wish .. propably far in the future, but then no
triangle would stand between Maxwell and the reality
