## 7. Constraints: Interpreting Line Drawings

MIT 6.034 Artificial Intelligence, Fall 2010

View the complete course: http://ocw.mit.edu/6-034F10

Instructor: Patrick Winston

How can we recognize the number of objects in a line drawing? We consider how Guzman, Huffman, and Waltz approached this problem. We then solve an example using a method based on constraint propagation, with a limited set of junction and line labels.

License: Creative Commons BY-NC-SA

More information at http://ocw.mit.edu/terms

More courses at http://ocw.mit.edu

MIT 6.034 Artificial Intelligence, Fall 2010

View the complete course: http://ocw.mit.edu/6-034F10

Instructor: Patrick Winston

How can we recognize the number of objects in a line drawing? We consider how Guzman, Huffman, and Waltz approached this problem. We then solve an example using a method based on constraint propagation, with a limited set of junction and line labels.

License: Creative Commons BY-NC-SA

More information at http://ocw.mit.edu/terms

More courses at http://ocw.mit.edu

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I am finding this hard to grasp, is there any other resource one can suggest to understand this?

I thought MIT would have really good professors. I was so wrong.Even MIT is not spared from bad teaching.stuff of the object, octants ,so vague.

I want to clarify how to distinguish the concave, convex, and boundary lines.

1. If you see 2 faces on each side of a line, then the line is a concave or convex line, depending on the angle of the 2 faces: angle > 180 is convex, and angle < 180 is concave.

2. If you see 1 surface on a side of a line, on another side, it is space, air, or nothing, then, the line is a boundary line. The way to determine the direction of the arrow on the line: the surface(object) you see is always on the right side of the arrow.

i.e. if the arrow points to left in a horizontal boundary line, then the surface(object) is above the line;

if the arrow points to up in a vertical boundary line, then the surface(object) is on the right side of the line.

If I am not clear enough, leave a message here to ask me.

Hoffman is a genius. Once the 4 line types and 18 possible junctions are laid out, the rest is clear.

The only i know is that if I can't visualise those line drawing into 3D object, I can never make a program that does that.

The prof's program said that the drawing at 47:55 was unambiguous and could represent only one scenario but i think 2 are possible.

1. A viewer watching a staircase normally such that goes from the left to the right

2. A viewer watching a staircase from below it such that it goes from left to right

How is this even important ?

I think this is redundant today(maybe wasnt 7 years ago)

How is he deciding the direction of boundaries ? XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXOOOOOOOOOOOOOOOOOahhhhhhhhhhhh

What's "stuff of the object" ?

I hate it when people use vague terms

21:02 How are 2 convex and one concave?

Shpuldnt they all be concave ?

unbelievably smart.

Trihedral vertexes modeling

here is a little pdf … https://drive.google.com/file/d/0B4s0uhYYRC1baVdfZG5NcGpJQWc/view?usp=sharing

showing a sketchup 3d the model @ 30:00 that could really exist

Whatever is in the cup, it's strong.