What does xnormal do for two meshes with non-zero transforms?
Out of a gut feeling, I would say that a tangent space normal map should
be independent of an object´s world space transformation, because if it
where dependent on that worldspace position, it would degrade the tangent
space map into an incorrectly created object space normal map.
It doesn´t make sense to take worldorientation of an object into account
for a tangent space map. Here the mother of all is one and she is perpendicular
to the face.
Nobody else has binormals anyway, sort of.
In terms of using empathy, I would guess that the code for Ultimapper was tested
against two objects in the origin and this resulted in the vertexpositions being
used as in (my pseudologic) worldspace=objectspace.
I would opt to have the tagentspace map created solely based on the distance
between two closest points (e.g. closest distance between in highrez and the
lowrez).
This way, the map will work, regardly of where it is or at what orientation to
the origin
it was created.
tim
On 06.01.2014 19:34, Matt Lind wrote:
It's a simple question of what is the expected result.
Should the tangents and bitangents stay oriented relative to the mesh, or
should they stay put in world space and acknowledge the transformation of the
object? My code is working under the assumption of the former, ultimapper is
giving me the latter.
See example scene I provided in my previous message.
Matt
-----Original Message-----
From: softimage-boun...@listproc.autodesk.com
[mailto:softimage-boun...@listproc.autodesk.com] On Behalf Of Szabolcs Matefy
Sent: Monday, January 06, 2014 12:22 AM
To: softimage@listproc.autodesk.com
Subject: RE: ultimapper issues - tangent space normal maps
Have you tried other solutions? Try it with xNormal to check your results. In
my opinion Ultimapper is quite useless without cage. Since we left Ultimapper
out of the formula, we have no issues at all.
Back to your problem. As far as I know, there are three normal mapping type,
world, object and tangent space normal maps. World space is the best for static
object, that have no transformation at all. Object space normal maps allows
object transformation, while tangent space normal maps allow deformation as
well. If tangent normal map changes when you transform the object, it might be
a bug. I'm not into the math of tangent space normal maping, but as I
mentioned, without cage Ultimapper is aquite useless, so we dropped it.
Consider moving onto xNormal it's quite reliable tool
Cheers
Szabolcs
-----Original Message-----
From: softimage-boun...@listproc.autodesk.com
[mailto:softimage-boun...@listproc.autodesk.com] On Behalf Of Matt Lind
Sent: Saturday, January 04, 2014 2:13 AM
To: softimage@listproc.autodesk.com
Subject: RE: ultimapper issues - tangent space normal maps
It's not a normalization issue as the normal vectors are normalized in Euler
space before being converted to RGB color space. If it were a post process
problem, there would be differences in all cases. So far I only see the
difference when one or both meshes are transformed indicating it's a coordinate
space computation issue.
There is no issue with a cage either. See my previous reply to the this thread
with example scene. The cage is only relevant when there are many layers of
overlapping surfaces. In my example it's a simple cube and sphere, so no need
for a cage.
Matt
-----Original Message-----
From: softimage-boun...@listproc.autodesk.com
[mailto:softimage-boun...@listproc.autodesk.com] On Behalf Of Tim Leydecker
Sent: Friday, January 03, 2014 3:11 AM
To: softimage@listproc.autodesk.com
Subject: Re: ultimapper issues - tangent space normal maps
Hi Matt,
A shift in the final intensity could come from a per channel normalisation.
You´d get different results if you don´t have such normalisation/levels
operation as a postprocess of your saving calculations to file.
But it should be easy enough to test if suc a normalisation would give you similar
results to XSI. In the dirtiest&cheapest way, in Photoshop>Auto Levels.
Since Szabolcs already pointed out that there is no cage option in Ultimapper, e.g. no
manual control of a min and max searchdistance for calculations, I´d guess the min and
max is fixedly determined by the maximum distance between highrez and lowrez mesh and the
results are "smoothed out" by remapping to 0-1 per channel for best use of the
file´s available intensity steps.
I could be completely wrong, thought.
In general, I will most likely use ZBrush and CrazyBump to create and modify Normals
in a let´s say, artsy partsy mashed potato kind of way that gives me the look I want
without knowing much more than Green>light from Ground, Red>light from Right to
work in Cryengine/UDK/3DSMax.
Cheers,
tim
On 03.01.2014 07:51, Szabolcs Matefy wrote:
Hey Matt,
Your result might be different because of the tangent space
calculation. I suppose that the normal map calculation might be done in object
space, then Ultimapper converts it into tangent space. Ultimapper could be
quite good, but lacks a very important feature, the cage. So finally we dropped
in favor of xNormal.
You might check few things (I'm not a programmer, so I may be wrong).
Check the transforms. In my experience transforms has effect how vertex normals
are calculated. Certain distance from the origin might result imprecision (is
this the right word?), and the farther the object is from the origin, the
bigger this imprecision is.
There are discrepancies, for sure, because these tools have different
approach to derive tangent space. For example, Softimage uses the
vertex color to store the tangents, and binormal is calculated from
this. But, if your smoothing on the geo and on the tangent space
property differs, you won't get any usable normal map. For example the
smoothing on tangents made Ultimapper quite useless for us, so I wrote an
exporter for xNormal, and since then we have no issue at all. As our technical
chief explained, a normal is correct only if the normal baking and displayer
use the same tangent calculation. He wrote a tangent space calculator for
xNormal, that uses the same algorithm CryEngine uses. So, unless your game
engine approached tangent space differently than Softimage, you won't get good
result.
I think the whole game pipeline should be redesigned in Softimage.
*From:*softimage-boun...@listproc.autodesk.com
[mailto:softimage-boun...@listproc.autodesk.com] *On Behalf Of *Matt
Lind
*Sent:* Friday, January 03, 2014 5:17 AM
*To:* softimage@listproc.autodesk.com
*Subject:* ultimapper issues - tangent space normal maps
I am writing a modified ultimapper to convert tangent space normal
maps from one mesh to another. The tool is needed because our tangent
space normal maps are not encoded in the standard way and softimage's tools
cannot be modified to support our proprietary tangent space. For prototyping
I'm using the softimage tangent space and tangents property to do the transfer
so I can check my math against ultimapper. Once I get a 1:1 match, I'll modify
the logistics to support our proprietary stuff.
So far when the hi and low res meshes are untransformed I get a 1:1
match with ultimapper, but when I transform one or both meshes a wide
discrepancy appears between my result and the softimage ultimapper
result. The softimage result tends to be significantly brighter on the red and
green channels, mostly on the green. In some cases, the colors are not even
close to the same. The odd part is when I trace through the process step by
step to debug, my numbers look correct both visually and mathematically. I'm
in a weird situation in that I do not know who's result is more correct, mine
or Softimage.
Some of our artists have mentioned there have been some discrepancies
compared to other commercial normal mapping tools (beyond flipping the Y axis).
Has anybody had issues getting correct results from ultimapper when
transferring tangent space normal maps between meshes?
Matt
