Oct 27, 2009


One day I needed to make very organic shapes on a scratch-build model. I put together all the basic parts knowing that I would have to fill all sharp corners and round-off all hard edges using the only putty I knew at the time, Tamya Putty.

Stop laughing

I won a prize for that model. First place in the SciFi Vehicle category. Of course, after I explained my methods to the other guys, I could have also won first place in the Idiot's Method category. That's when I learned about Super Sculpey, Milliput and other sculpting medium that everybody was using, except me of course.
If you didn't get the joke: Tamya Putty is to fill small cracks only. To use it the way I did, it's like trying to extend a wall using wall putty.
One of the modeler, whose work I admired, was working with Milliput. That was all I needed to select it as my future medium. Ha Milliput! I could finally make any shapes I wanted. I started making figures sculpted entirely by hand. Nothing could stop me now... except Milliput!

The thing is, it's a two parts epoxy paste that, out of the box, as the consistency of a dried bubble gum. Here are the steps for using it:

1: Make sure you have at least one hour to invest in this. Milliput takes time to mix and stays soft for only forty five minutes. After that, it's as malleable as depleted uranium.
2: Keep a small bowl of water and a rag near you on the table.
3: Guesstimate as best as you can the exact volume of Milliput you will need and add 20%. This stuff is expensive and once it's mixed you have to use it or it will be lost. My best advice is to always have a rough area to fill-in where you can put the small excess you will have. Don't under estimate because it sucks to remix a small batch.
4: Cut equal amounts of material A and B using a strong blade. (Remember, this is really hard stuff)
5: Try mixing the two parts into a perfectly even material by pressing, bashing, slicing & stacking and mushing the batch with your thumbs. It must be even or you will have holes in your surface. This takes about five minutes but it feels like thirty. At the end your thumbs normally feel as if you've cut your nails way to short and it's sensitive every time you push on their tips.
6: Start using it! You only have forty five minutes and it will get harder every minute. If the Milliput start sticking to your fingers, keep them wet by dipping them in the bowl of water next to you. When it gets to messy use the rag.
7: The next morning, once it's dry, you can use any kind of carving methods to continue shaping your surface.
8: To complete the sculpture, repeat those steps about fifty times.

This is not a joke. I used this stuff for years (from 1996 to 2007) and I had to do that every time. Needless to say that it was an adventure.

By the way, I'm now using Castilene for the last two years.

Oct 18, 2009

Precise imprecision

Have you ever thought about how many types of intersections exist for two lines? Just two straight lines, either in 2D or 3D, bounded by two points (not infinite). And only counting the intersections that fall on one of the two lines, including their end points. You probably didn't, because it sounds pointless.

Well, I had to think about that one seriously while working on a problem back in 2001. It looks simple at first. You start imagining the type of intersections:
  • The two lines crossing in the middle

  • One end of a line touching the other one

  • One end of both lines touching each other

Then you think about that one:

  • The two lines completely overlapping

And that gets you to:

  • The two lines partly overlapping
  • And both overlapping combinations with a short and a long line...

In that completed list, you arrive at 7 types of intersections. That would be OK in a perfect world where everything is on a nice grid and points are either on or off the line.
In the real world, lines don't fall perfectly on each other. Many times, two points will be really, really, really close but not touching. That's when you start working with an allowance for imprecision. Doing that, you round up numbers for which the difference is smaller than the allowed precision. So in a 3D world, you would consider two points that are close enough together as one point. This then creates a perfect world with 7 types of intersections... or does it?

Not really, if you're picky like me. Because, with this approach, the data changes with each correction created by the precision rounding. So I asked myself: what would happened if I didn't move the rounded points? What kind of intersection types would that create? After a lot of work, I finished a new list of intersection types. Starting with the original 7 types of intersections, I identified variations for almost each of them. And because of the imprecision allowance, I also found a whole set of sub-cases with each of them acting as a multiplication factor on the base types. This brought the grand total to 129 types of intersections.

129, Ouch!

So, next time you think something is simple... think twice.

Oct 15, 2009

Flatland 2.0

In the novel Flatland, the sphere fails to enlighten the square about the existence of a 3rd dimension. In the end the sphere simply gives up and pushes the square out of its current plane. This make him hover above his flat world and see it from a 3rd dimension point of view.

This never made sense to me for two reasons. First, this is an easy way out of solving the problem of explaining the 3rd dimension to a 2D being. Second, the square does not acquire a new sense of vision because he is outside of his original plane. He would still see the world through a flat input. What he would see would be incomprehensible to him, the same way the sphere was appearing, morphing and disappearing by intersecting with his plane. All 3D shapes would still look like that to him and all 2D shapes (from his plane or any plane) would look like points and, occasionally, lines.

Is it possible to explain the 3rd dimension using only only 2D terms and their relation to 1D and 0D? That's one of the things that I'm working on...

My poor brain

Explorer or Poet?

Have you ever worked in companies that apply every year for Canada RS&DE? I have... many times. Over the last 16 years a clear pattern was always present. It is my belief that people applying for R&D credits fall in one of the two following categories: Explorers or Poets.

Explorer: Sees his home as a port from which he comes and goes, because the real action is out their. Thrives in finding new physical things before anybody. Is never afraid of failing and so, is always trying again and again.
Poet: Loves the security of home. Can sometimes go as far as the park in front of his home or even the cafe two blocks away. Excels at seeing things from a new angle. Is so alarmed by the idea of failure that, most of the time, he will extract new views from things he knows.

An Explorer-type company works with the uncertainties of experimentation all year long. At the end of the year, their R&D report is already filed with real research and they can go about their normal business.
On the other hand, the Poet-type company reheated last years stuff to capitalize as much as possible on existing technologies. At the end of the year though, the R&D report is empty. That's when the Poet enters the scene.

Oh dear Poet, can you write me something beautiful, inspired by this everyday stuff?

Make it sound new, I hope I'll get 60% of my reclamation.


Oct 14, 2009

Machine Reading

A Machine Reading system would be able to parse any documents and extract all the info, like people, places, time line, any associations between those things and more. It would also have to understand innuendos, ambiguities, sarcasms and backwards logic to understand the real meaning of a text. It would be nice for many application domains like book publishing, web search, forums policing or spying.

Are you nervous now?

A program like that doesn't exist right now. This looks to me like a perfect NP-complete problem. My guess is that it's worth a PhD at the very least... But for that you have to be able to publish your results. Why is that relevant? Because, it looks like the first application of that type is not going to be from the private sector but from the military. Yes, DARPA just gave a 5 year contract of nearly 30 million dollars to BBN Technologies to 'build a prototype' of a fully functional machine reading AI.
Oh, and yes you will need a security clearance to work on the project.

How about now?

For my part, I wish Goolge was building a thing like that and would make it an Open Patent. I also wish I was working on the project but that's another story.

Oct 5, 2009

What's the points?

Back in January 2007, I was browsing Paul Bourke's web site, looking at amazing images generated from fractals. Like most people I find that some of them have an artsy side and would fit perfectly in a modern art exhibit.

Then I came upon this one:

$ x_{n+1}=\sin(ay_n)-\cos(bx_n) $
$ y_{n+1}=\sin(cx_n)-\cos(dy_n) $

It was generated with a mathematical attractor named 'Peter de Jong'. It was simple, no colors and the rendering wasn't that great. Even though all the points are in a single 2D flat plane, I couldn't help seeing depth in this image. To me, there's a bunch of translucent surfaces in a 3D space.
Of course, at that point my brain started working on overdrive wondering what it would take to separate the points for real and see the shape expanding into a 3rd dimension. So I've set some basic rules for this experiment:

1) Only use the existing X and Y data to generate the new Z data.
2) Never modify the existing X and Y data.

I called this process delamination, because it's like trying to separate different layers glued on top of each other. So far I've achieve 80% to 90% delamination. I only understand 20% of the process and I'm analyzing my results to figure it out.

Also. If you've worked on something like this, I would really like to talk with you.

Oct 4, 2009


I sculpted this during an on-off period between 2000 and 2003. Most of it is made of Milliput, a really hard epoxy-base compound I will never work with again. The painting was done using acrylic.

The figure is about 1:10 scale and depicts Cdr Eugene Cernan during Apollo 17th and last moon landing mission.