On Wed, Mar 14, 2012 at 7:45 AM, brlcad <brl...@mac.com> wrote:
> n Mar 14, 2012, at 05:45 AM, Animesh Garg <garg.anim...@gmail.com> wrote:
>
> Hello BRL Developers,
>
>
> Hello Animesh! That's a great 3D-graphics name you have there. ;)
>
> Thanks a lot Sean, for the descriptive reply.
> I have a background in optimization & stochastic modelling (operations
> research), robotics, computer vision. I have taken graduate courses in
> vision, studied and taught undergraduate Computer Graphics and Database
> classes. I have sufficient programming experience, mainly in c/c++ and
> matlab for robotics/vision domains where I implemented custom algorithms
> and worked with robot hardware. Furthermore, I am comfortable using either
> Linux or Windows. I have worked on projects with subversion.
>
>
> Certainly a lot of BRL-CAD relevant background experience you have there,
> welcome to the community. Most of our projects that will probably be most
> interesting to you are C/C++ so it sounds like a good fit.
>
> I have been glossing over project
> ideas<http://brlcad.org/wiki/Google_Summer_of_Code/Project_Ideas>.
> Most of the development at brl-cad seems to be in c/c++ barring a few
> projects.
> Top projects that interest in me , in order of preference, are :
>
>
> We're adding new ideas every day so don't be shy to suggest a new idea as
> well if there's something in particular that piques your interest we
> haven't mentioned. Particularly with your background in computer vision,
> there's a lot our ideas page doesn't mention but BRL-CAD has been involved
> with in the past.
>
> 1. Geometric Constraint Solver
> <http://brlcad.org/wiki/Geometric_Constraint_Solver>
>
>
> How good are you reading existing code? What about somewhat complex C++
> template class code? Our libpc parametric constraint library is built on
> top of Boost's Spirit library. Dawn can certainly speak more to the
> current status but I can say that this is a high-priority hot topic, so
> glad to see you're interested. As it is, the library is in place and it
> has test code that evaluates basic expressions correctly. We're actually
> in the process of integrating the existing solver in with our primitives
> right now so that known implicit constraints can be automatically evaluated
> on-demand. From there, the intent is to have explicit constraint entities
> that describe one or more relationships on geometry.
>
I am fairly comfortable reading and understanding standard code, and
hopefully would be able to get a head start on #1.
As you suggested, I hope that Dawn can describe the state in relatively
greater detail.
> 2. Vector output from
> Raytracing<http://brlcad.org/wiki/Vector_output_from_raytracing>
>
>
> This is a fun project that could either be implemented in the output 2D
> image-space domain or as a projection of 3D geometry. The prior is
> sampled, the latter is not. The latter is the more desirable way to go,
> but the one where we lack a critical routine (evaluate surface-surface
> intersections of NURBS surfaces). Doing it in image-space should be
> suitable but begs for adaptive sampling to make sure detail is captured
> appropriately.
>
> I would be very interested in this one as well. I would like to try to
test out the surface-surface intersections in 3D which then can be
projected to give out an vector image(.svg) as output.
> 3. Density Function <http://brlcad.org/wiki/Density_functions>
>
>
> This is a cool one. It's more about API restructuring than anything, but
> the impact potential is pretty grand (most CAD systems can't do this). The
> idea is to parametrically describe an object's material properties as a set
> of density functions. Given a particular ray slicing through an object,
> you'd get back a density function for all segments hit by the ray. An easy
> way to conceptualize this is to take a "core sample" of a bone. Bone is
> considerably more dense near the surface and gets progressively less as you
> move towards the center. You'd probably define density as a function of
> distance from the surface or distance from the medial axis.
>
>From my understanding of the problem, I would need to parameterize the
density of the material along the ray on the distance from the surface or a
relevant metric.Also this density distribution is ray-specific, and we only
need an output for a ray.
Furthermore, do you think it is possible (and needed) to sample rays, to
get a set of these density distributions, and then render them as heat map
(red for sense-blue for less dense) superposed on the object in 3D. Also we
can then define a control, where the user can run through the object (in
the same way we run through a 3d volume of CT-Scan slice by slice). And
each slice (or cross-section) would display a combination of the densities
along all the rays normal to that slice at that particular depth. This
might be useful in structural analysis.
>From your description of the problem, I believe this is a relatively low
hanging fruit, and I would like to complete this task in the first part of
my term, in case I am chosen.
>
> I would be glad to discuss possible proposal with brl mentors before
> finalising my idea. It would be great to get input on current state of the
> above problems, and also what would be a good set of goals, non-trivial but
> not impossible, to complete during the summer.
>
>
> Follow-up questions are certainly welcome (and other devs are encouraged
> to chime in if I left anything out or you just want to add something to the
> discussion).
>
> Cheers!
> Sean
>
You provided helpful insight on the state of the projects and goals.
Honestly, I am equally excited by all three and would like to start doing
the easiest and then move on to either, in case time permits.
I would like to take up #3 and #2 and primary focus of my proposal. Because
their completion would benefit more than solving one harder problem.
However I am open to suggested projects, especially in Vision. I would be
glad to know some of the features that you may want and how may I
collaborate. Hopefully other developers from BRL can help me out here.
One more piece of advice, would it hurt my application if not substantial
pieces of my previous code are not open-source. ( I cant release them due
to several research commitments).
Regards
Animesh Garg
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