The relation between the lowrez and highrez mesh is the responsibility of the
modeler, imho.
Retopo has become a lot easier but shouldn´t be mistaken to be automagic just
because there´s
now several options in various programs to autogenerate some sort of cage
around a mesh.
Of course, it´s good to talk and find a general approach on how to handle
bevels or rims,
how to sculpt highrez stuff to make sure it transfers nicely and looking into
maybe even
temporarily subdividing a uv´d lowrez mesh to improve bake results. Fat edges
don´tlook nice
in a highrez but may just stand out better from a distance later...
The final cleanup and adjustment (involving some trial and error) of the lowrez
mesh should
really be the seen as the resposibility of the person that created the meshes
and not passed
on to the guy just painting the texture. Ideally, you provide options to
iterate quickly
and brute force it if really neccessary. Fiddling looks like struggling to the
uneducated observer.
I´ve worked in two, three scenarios that where shotgun style task driven and
found that some
types of personalities may be tempted to forward the problem for the sake of
finishing their task.
This results in unfair workload that may slip the attention of the production
team.
Been on the receiving end a few times, including a feature film involving trees
without treetops in an establishing total shot.
That leads to some sort of frustration avoidable by actively sharing and
distributing responsibility.
But for that you need a sup and production team actually willing to involve
people in the decision making process.
Which seems rare to me, out of experience. Quite a few productions I worked on
suffered from the ego of the people
more than from tight deadlines, limited budgets or even artistic limitations.
Maybe that´s a german phenomenon.
Back to normals, the reason why I brought up the edgespill and 2D>3D
interpretation of images
is because it´s likely you´ll want to mix our baked highrez>lowrez normal map
with highfrequency
surface details derrived from a 2D process or even various sources.
In terms of first of all creating a good bake, I try to model a clean,
subdivideable basemesh
and bake from high subdivision to lowrez of the same mesh, to avoid the
scenario you face.
But that is overkill and limiting both in terms of effort needed to model and
resulting time it takes.
People sticking stuff together, be it dynameshes, voxels or cubes will iterate
more, producing more, maybe even better results.
After a lot of trials and Errors, a highrez can be a pile of goo as long as it
looks awesome - which is what counts.
That said, the lowrez mesh should be clean and well made, no cheap shortcuts.
Still, I prefer a clean highrez mesh but it´s not supportable in a production
environment.
Cheers,
tim
On 07.01.2014 05:35, Matt Lind wrote:
The bigger problem that needs eyes on it is determining how the low res mesh
details correlate to the high res mesh details. Maya uses a cage concept to
limit the search distance, but that doesn't address the issue of finding an
appropriate match for a specific detail common to the two meshes. One possible
solution is to duplicate the low res mesh and ask the user to push and pull
points around under the direction that rays will be cast from the low res mesh
to the duplicate mesh along the line that matches the details. If the high res
mesh is encountered along that path, then the normal will be transferred to the
low res mesh. That works, but is probably more labor intensive to set up than
any user would want to deal with.
I am only trying to solve a very specific problem of being able to transfer a
tangent space normal map from one object to another using our proprietary
tangent space algorithm. I'm still at the prototyping stage and testing with
standard tangent space algorithms to validate my math before proceeding to our
proprietary algorithm which has a few added wrinkles.
Edge spill in the context of an ultimapper-like transfer process is really
about oversampling. As long as the entire texel is tested against a triangle
and not just the centroid of the texel, there shouldn't be any issues. What
can be a problem is if a texel is used by multiple triangles on different parts
of the mesh (i.e. the UVs are not unique). That's when you run into garbage
data contaminating your normal map. If your UVs are unique and there's at
least one pixel of safe zone around each UV Island, and you adjust oversampling
to do some sort of stochastic sampling to ensure all parts of a texel are
considered, then you shouldn't have any problems with edge spill looking like
crap or allowing undesired values to bleed in.
As for the normal map from image or heightfield techniques. That's an entirely
different ballgame as the as the tool is making assumptions about a 2D space to
fabricate a 3rd dimension. While it will produce valid results, it may not
always be desired results. Higher resolution data will produce better results,
but it'll never be as accurate as having 3D data as a source.
Matt
-----Original Message-----
From: softimage-boun...@listproc.autodesk.com
[mailto:softimage-boun...@listproc.autodesk.com] On Behalf Of Tim Leydecker
Sent: Monday, January 06, 2014 7:19 PM
To: softimage@listproc.autodesk.com
Subject: Re: ultimapper issues - tangent space normal maps
It is great to have flexibility in the search methods.
I´m familiarizing with xNormal at the moment and just went through the
Normalmap sampling options, e.g. 3x3,5x5 etc. I can´t say I am sure I have a
favourite search method for a specific task or know why, yet.
From my artistic standpoint, I have a good idea what I want a specific
Normalmap to look like, it´s just a bumpmap with additional info about it´s
orientation to lightsources. Easy enough to read in 2D and translate into a
guestimate what it´s going to give me for details (in the specs) in an
otherwise boringly flat surface.
I would likely favour a clean version over the one with artifacts from scaling.
This includes avoiding edgespill, harsh contrast and overly pushing intensity
to start me with.
To a developer implementing a Normalmap feature, it´s probably blasphemy but if
you look into
ndo/ndo2 and what options it´s giving an artist to influence/suggest surface
detail, it´s just cool.
ndo/ndo2 or crazybump or xnormal start to hurt when you do "normals from
heightmap/photos) or from a painted diffuse map and look at what consequently
happens to the edges of your uvshells.
It´s difficult to judge how much clean edgespill is going to be needed, I try
16x at 4K but that already takes away a lot of map space just for making sure
downscaling to 1K may work.
Why I´m saying this?
It would be nice if you make sure edgespill around your UV shells is first of
all there and ideally not maxed out into rainbow colors as in, let´s say
Mudbox. Adding layers to such an area afterwards is really difficult otherwise
and may give you artifacts creeping in on your map area fron the seams.
Cheers,
tim
On 06.01.2014 21:06, Matt Lind wrote:
OK, so what I'm hearing is we both agree ultimapper is wrong. That's what I
needed to know.
I'll file a bug on ultimapper and proceed under the assumption my code is
correct.
Thanks.
As for looking up a normal on a high res mesh from a low res mesh, ultimapper
is using raycast along the low res mesh's normal to find the appropriate
location on the high res mesh. If the ray shoots off into outer space without
hitting anything, a 2nd ray is cast in the opposite direction. If that ray
hits nothing, the normal is recorded as (0.5, 0.5, 1) indicating the tangent
normal map stores the geometry normal as is.
If you do a closest location search as you suggest, the results are often quite
different. Using the example scene I provided in a previous message, the
raycast method as described above results in a circle being drawn on each face
of the cube. If you do a closest location search, the entire cube will be
filled with normals and that map will have heavy amounts of distortion. In
some cases that may be desireable or more appropriate than raycasting. In
either case, I don't think there's a blanket solution to that problem. The
search method has to be tailored to the specific case.
Matt
-----Original Message-----
From: softimage-boun...@listproc.autodesk.com
[mailto:softimage-boun...@listproc.autodesk.com] On Behalf Of Tim
Leydecker
Sent: Monday, January 06, 2014 11:20 AM
To: softimage@listproc.autodesk.com
Subject: Re: ultimapper issues - tangent space normal maps
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
