To-Do List for the Dynamic Scene Generator
There are plenty of tasks that still need to be done to make the
DSG everything we want it to be. Here's a list of the ones that come
- Disappearing scenes.
When playing with the DSG, occasionally a scene that has models
in it will go completely black. This often happens when you
zoom in or when you look at a particular structure. Why? It
seems that the camera's "diameter" parameter, which controls
the front and back clipping planes, gets set too small and then
clips everything out of the scene.
One way to fix this with the "look at" function is to
remember the diameter before calling :frame-things on the
object of interest, and then restore the diameter value after
the call. I'm not sure how to deal with the zooming in case.
- OBJ model problems.
The OBJ models generated by Shawn's bodygen program have a
couple of problems as far as Skandha is concerned. First,
facet vertices are listed in clockwise order instead of
counter-clockwise. Since the convention for Skandha (and for
OBJ files in general) is counter-clockwise ordering, the
normals that Skandha generates for these surfaces will be
Second, each point on the surface gets listed twice---once for
the ribbon above it, once for the ribbon below. This makes it
more difficult to compute point normals for the surface. When
loading OBJ files, I included a call to
xvol-merge-redundant-points to deal with this, but it
would be better dealt with when the OBJ file is generated.
If you want to experiment with an OBJ model, I have set up a
"lung-demo" model set. (See modeldb.lsp, corr-lung-demo.lsp,
and ~hinshaw/work/3d-formats/rlung.obj for details.)
Feature Wish List
- Connect to the new FMA server.
Peter Mork and JJ are working on a new FMA server, which will
connect to the current Protege knowledge base instead of the
very old and out-of-date one it currently uses. Once they have
it working, we want to change the DSG server to use it. The
Lisp-like query syntax will be identical. However, the
representation of some knowledge has changed (e.g. part-of
relationships have gotten more complex). Some DSG code will
need to change as a result.
- Unify term-server.lsp with xfms.lsp.
There are two different pieces of skandha code that connect to
the FMA server: xdada/lsp/term-server.lsp and
xscanner/lsp/xfms.lsp. There a couple neat tricks in xfms.lsp
that should be merged in with term-server.lsp, in particular the
- Switch to PNG images.
Have the DSG generate PNG images instead of
TIFF images. This would avoid the buggy TIFF problems we have,
and would also bypass the current TIFF-to-JPG conversion step.
- Add brain models.
As soon as the DSG is talking to the new FMA server, it will be
able to access knowledge about brain anatomy. A set of
primitives and the list of correspondences are available in
need to copy correspondences.txt into the xdada
module's lisp directory, and edit it to match the current
file format, which lists structure name on one line, followed
by the model name on the next.
- Make a real 3D model database.
The current "model database" is just the set of correspondence
files that link an FMA concept name with its 3D model. This
information should be in a true database.
- Read/write better scene description files.
We are thinking of using
as our default scene description
language. This is the next generation of VRML, but using XML
to describe 3D scenes. This means we'll need Skandha code that
can import and export X3D format. Code for XML import/export
might be a useful first step in this direction.
- Create better clients.
The forms-based client is difficult to extend and maintain
because of the difficulty of maintaining state between web
clicks. Alternatives for new clients include:
- Java applet clients. Bruce Campbell created the start of
a Graphics Server Componentization (GSC) project, which
implements an interface builder kit, in which widgets can be
associated with each dsg Lisp command, and dragged onto a
canvas to create a custom application. A description of this
can be found from Bruce's SIG
home page. Click on the Graphics Server Componentization
Project link. The source code is checked into CVS as src/scenes/GSC.
- 3-D client-side viewers. Eventually we will want to
allow rendering on the client side in
order to permit rapid user interaction. In
this case we will want the dsg to simply
generate a scene description as note
above. Then a client program could read in
the scene and permit user action. Current
efforts in this direction include a
C-based viewer being developed by Shawn
Bonham, and explorations of the
feasibility of Java3D, which now has
Return to the DSG project page.
jfb, modified from kph
Last modified: Wed Feb 5 10:28:23 PST 2003 by Kevin Hinshaw (khinshaw (at) u.washington.edu)