[fuso]

Hi guys,

It's been a while since I've posted around here so I hope the community
is as responsive and helpful as ever before! Also I hope this problem was
not covered in older posts but if so, please embed a link so I can find it
and I apologise in advance.

Recently I came across a rather nasty bug which I thought was because
of a slightly corrupted file so I didn't take it too serious. But then I
experienced the same problem in an increasing number of files. I am
using the latest Maxwell Render core and plug-in for Autodesk 3ds Max
Design 2009.

The problem is with the shadows cast by the tree, as you can see in the
two attached images. I really thought I was going mental when I noticed it
first time as I really struggled to make sense out of what I was looking at.

As you can see there are weird silhouettes within the tree shadow coming
through as well as there are parts of its shadow and reflections missing on
the windows (AGS glass in use).

Those structures imprinted into the tree shadow area of the front wall are
objects which are way behind that face where the shadow is cast onto. I
tried assigning different materials to both objects with no visible change.
Furthermore I tried replacing the object receiving the shadow with a
simple block - unfortunately also without a change. Then I started to
hide objects which were behind the front building not affecting reflections
or shadows cast onto it too much - success!!

A few of those objects are cloned instances within Max, if this might lead
to any logical explanation? The tree and the brick building itself are not
instant clones and modelled/placed individually.

In order to eliminate any other sources for this phenomenon I double
checked all my geometry, as well as materials including all their maps
and bump values, etc.

Has anyone around here experienced anything like this before and would
be able to shed some light into this? Thanks a million for any help, advise
or explanation on this issue...

Jost


By jost at 2009-04-20


By jost at 2009-04-20

[m-Que]

A few of those objects are cloned instances within Max, if this might lead
to any logical explanation?

I think you can not use instances of the modeler (in your case Max) if you want render the scene in Maxwell. But I'm not sure about it, and I'm not a Max user, ether.
Perhaps you could try removing all the Max instances, and then rather just clone them or use Maxwell instances.

[Bubbaloo]

Max instances work just fine, M-Que. I use them all the time.

Man, that is so strange! Do you render straight from the plugin or export to mxs and then open in MXST to render? Try rendering with and without the "use instancing" box checked in the Max plugin. Also, what I would do is start a clean Max scene and import your old scene into the new one. That has solved a lot of strange problems for me over the years.

[pendi]

I am also facing the same problem, instances are not working either in 3dsmax or in maxwell render, you have to make instance objects to unique or just clone them..then it will work, instances from max not working..

[Mihai]

Would it be possible to do a Pack & Go of this scene and send it to me? Does it do the same thing if you open the mxs in Studio and render it?

[fuso]

Hi again,

First of all thanks for all the replies so far. I have received a message
from Tom already so I believe he's on the case. Here is what I replied to
him as I tried to clarify the problem a bit further:

Morning Tom!

Thanks for your quick reply. I thought you guys would be interested to
get your teeth into that phenomenon. But to be honest I'm quite surprised
that no one else has come across that problem yet. So far it has only
appeared in two Max scenes I have modelled from scratch but it's really
doing my head in...

It would be difficult to recreate since it seems that the bug only shows up
when a scene becomes rather complex as well as it seems to be so
random that it's really hard to locate it! My gut feeling is that it's
connected to the clip maps of the x-frog trees I'm using. But then I did a
test where I have assigned a very simple lambertian material to both, the
tree and the building - same result. I could also imagine that it may as
well be the translation of the instances?!?

Tom I don't know if you're aware that when you enable the 'use instances'
option in your Max/Maxwell plug-in render settings you'll get to see the
chaos from hell... So I keep leaving that one ticked off for sure since a
while already.

As I said in my post, the only way of getting rid of it was by hiding objects
behind that building as well as in the rest of the scene outside the visible
area. Many of those objects are instanced and clip mapped as well. The
geometry of the building was created using the new Power Booleans built
into 3ds Max Design 2009 but I have already converted it into a mesh and
checked all normals, the UVW map and smoothing values.

Tom I hope this clarifies the problem a bit better and that you'll be able to
help at some point. I wouldn't mind sending the file in any format but I
need to check first with the team as I believe it's quite confidential. Not to
mention the size of the file including all the maps. But I'll see what I can
do about that.

As I think this is a major problem and that it creates a lot more additional
work I am more than just hopeful that this will be fixed in the next major
release and that this great render engine will finally leave all its teething
troubles behind... As a very loyal customer this was the first time when I
seriously thought about switching back to mentalRay.

Thank you very much in advance and I hope to hear back from you soon.

Kind Regards,

Jost

[tom]

Replied in PM.

[fuso]

@ Bubbaloo, pendi and m-Que: I cannot confirm without blushing dark red
that instances (clones) from 3ds Max are translated well through the
plugin. I had similar problems in the past but they were too minor to
mention and relatively easy to fix.

@ Mihai and Bubbaloo: I always render straight from Max as it suits my
workflow a lot better, so I have to admit that I'm not using MXST much. I
believe the plugin should provide me with all I need. But I will give it a go
and also I'll try to chop down the scene as small as I can but with the bug
still appearing.

Thanks again for all the replies so far!

[tom]

Thanks for the scene! I reduced it down to a single problematic object, which it the building walls itself. Still working on it but I can confirm the problem has strictly nothing to do with the materials, instances, clipmaps, AGS and/or the scene setup etc. Because, now I have this problem under skydome with this single object using the default lambert material. I'll give more information soon... It was really helpful, thanks!

[fuso]

@ Tom: Thanks for sharing this but do you remember that I did a test
render with a substitute object for the building. I simply used the original
outline from CAD, extruded it about the same height but without all the
complex boolean operations. Then I assigned a simple lambertian
material, rendered it and ended up with the same artefacts. I can
recreate the same situation and post the result if you want me to.

Cheers,

Jost

[tom]

OK, we found the problem. It's because the building wall is Motion Blur Enabled.
I'm not sure how many objects have the same setting so, I suggest you doing
Select All + Right Click + Object Preferences and correct the following as:



So, everything will be back to normal. Apart from the solution,
this helped us addressing another bug related to shadows and motion blur
which is already fixed. Thank you!

[fuso]

@ Tom: Thanks a million for fixing that problem for now, you were right
with the object motion blur since my temporary substitute building had
that enabled, too. I rendered the original file again and it's just fine now.
What a weird bug! But does that mean that if I want an object to be
blurred in a fast animation, I have to enable it again or would it just not
render motion blurred if I leave it set to none?

Thanks again for helping out so quickly.

Jost

[tom]

Yes, you have to re-enable it in that case. But, you will have the shadow bug on motion blur which is present in 1.7 as we see.