Re: [Closed REQ 5016]: looking for conv's,3d-objects

["Tamara Munzner" <munzner>]

Dear Markus,

 First of all, there's an ftp archive at avalon.chinalake.navy.mil
which has converters between different 3D file formats and *many* 3D
objects. Even if the converter you want isn't there, you might be able
to use some of the ones there as a base to work from. 

  >>Do you know a converter off->nff
We don't have one here, you might find one at the chinalake site.

 > The only ones that I am aware of are those that are developed here at the 
 > Geometry Center, such as "anytooff", which takes an OOGL file and 
 > converts it into an off file.  

 >>Can I display OFF-,dxf-,nff-Files with Geomview?
 >>What else fileformats can I display.

OOGL is really a collection of many file formats, one of which is
OFF. Geomview can display any of the OOGL data formats, which include:
polyhedra with shared vertices (.off), quadrilaterals, rectangular
meshes, vectors, and Bezier surface patches of arbitrary degree
including rational patches. Object hierarchies can be constructed with
lists of objects and instances of object(s) transformed by one or many
4x4 matrices. See the Geomview manual for more details. 

There is also a Mathematica package that allows any 3D object you
generate in Mathematica to be displayed in Geomview. That package
comes with the Geomview distribution. Since you're building a house,
though, Mathematica is probably not the most useful tool.

 > We also have "ucdtooff", and "anytoucd", which takes UCD to OFF, and
 > OOGL to OFF, respectively.  I am not familar with the UCD format,
 > however.

UCD is Unconstrained Cell Data, which is an AVS format. (AVS is a big
dataflow scientific visualization package.) There are not many models
floating around the Net in this format.

 >This is Ed.  We talked on comp.graphics.visualization.  The file I sent 
 >you last week is "office.oogl", which is actually an OFF file.  This is 
 >the only file that I know of that gives what you want here at the 
 > Geometry Center.  Maybe someone in the center know where we have more??

 The file "office.oogl" that Ed sent you comes from the Berkeley
walkthrough project. The Unigrafix format has been developed at
Berkeley by Carlo Sequin's group, and is documented in 

  Sequin, Carlo H. Introduction to the Berkeley UNIGRAFIX Tools (Version
  3.0). Technical Report UCB/CSD 91/606, Computer Science Department,
  U.C Berkeley, 1991.

 While I was at Berkeley a few years ago, Tom Funkhouser quickly wrote
a Unigrafix->OFF converter, which we used to convert the office scene
(I've still got an SGI binary for the converter). Geomview, our 3D
viewer, can display OFF files. 

 The Berkeley walkthrough project has developed a full model of an
entire floor of a building with furnishings at many levels of detail
for use in graphics research. They may be willing to let you use some
of their models, try asking Seth Teller (teller at cs.princeton.edu). One
of his papers goes into detail about how they constructed the model:
 
@InProceedings{funkhouser-1992-management,
  author         = "Thomas A. Funkhouser and Carlo H. Sequin and Seth J. 
                    Teller ",
  title          = "Management of large amounts of data in interactive 
                    building walkthroughs ",
  pages          = "11--20",
  booktitle      = "Computer Graphics (1992 Symposium on Interactive 3D 
                    Graphics) ",
  volume         = "25",
  number         = "2",
  year           = "1992",
  month          = "March",
  editor         = "David Zeltzer",
  conference     = "held in Boston; 29 March - 1 April 1992",
  keywords       = "architectural simulation, virtual reality",
  annote         = "",
}

Here's the most relevant part of the paper:
------------------------------------------------------------------------
 Our walkthrough system requires a detailed 3D model of a building,
compelte with furniture and realistic material and lighting
information.
 We first convert the raw 2 1/2 D model received from the architects
in AutoCAD DXF format into a consistent 3D representation in Berkeley
UNIGRAFIX format. Unfortunately, the raw architectural models that we
received were not true three-dimensional models and contained
non-planar faces, coincident coplanar facdes, improper face
intersections, and inconcsistent face orientations. During conversion,
our programs detect and automatically correct many of these
anomalies. Any remaining modeling errors are corrected manually using
interactive tools.
 We then populate the architectural model with stairs, furniture and
other objects that a user would expect to find in a typical
building. We have generated highly detailed descriptions for several
pieces of furniture using interactive modeling programs, and received
others from Greg Ward of Lawrence Berkeley Laboratories. We place
instances of these objects into the building model using both
automatic and interactive placement programs. We have written several
programs that automatically place objects into specific types of rooms
based on sets of parameters. For instance, the "conference room
generator" places a rectangular or elliptical table in the middle of a
room, chairs all around it, a blackgoard on the wall, a transparency
projector on the table, and so on. The "office generator" places a
desk against one wall, a chair in front tof the desk, soom bookshelves
against the walls, and so on. Numerous parameters are available for
the user to control the size, number and placement of objects with
each of these programs. We ahve also written a program for
interactively placing objects into a three-dimensional model. It
allows a user to add, delete, or move object instances with real-time
visual feedback.
 Gradually, we load the walls and furniture of the building model into
the walkthrough display database. The display database represents the
building model as a set of objects (e.g. walls, desks, chairs,
telephones, pencils, etc.), each of which can be described at multiple
levels of detail. We construct less detailed representations of
objects from the highly detailed originals using an interactive design
tool that allows a user to simplify 3D objects by deleting and merging
verices and faces. For instance, we construct five representations of
a desk: 1) a highly detailed desk with faces subdivided along
gradients of radiosity, 2) a slightly less-detailed desk with simple
handles and larger faces, 3) an even less-detailed desk without any
handles at all, 4) a coatsely detailed desk with only legs and
drawers, and 5) a simple box. (.....)
 So far, we have built a complete furnished model of the sixth floor
of Soda Hall, the planned computer science building at
U.C. Berkeley. This floor model has a total of 2,320 objects,
represented at up to five levels of detail, and contains over 400,000
faces, requiring 68MB of storage.

------------------------------------------------------------------------
 Hope this helps,

Tamara Munzner          ((555) 555-5555
munzner at geom.umn.edu    The Geometry Center