The Origami Forum

Sometimes when I go through pictures on flickr, reference points are written out/ displayed. Thing is, I don't know how to understand them

Here is an example from Seth Friedman's Hermit Crab:



You'll have to do some ref finder work.
(sqrt2+1):4:4:(sqrt2+1)

Help would be greatly appreciated.

I did use the search thing and typed in 'reference point help' and I got 38 pages of results. So I'm sorry if this has already been asked

Well, you see those aren't reference points. They show the distribution of paper using cirlce/river packing. Each polygon represents a flap, and the gaps in between spread them out.

Hope that helps!

Robert Langs' designs use silly reference points too. The only way to find out were they are is to use a calculator and ruler, or download reference finder from his website: http://www.langorigami.com/science/reff ... inder.php4

As ted385 said above, what's on the cp for the hermit crab demonstates the ammount of paper used for each flap, sometimes they are linear like that, and sometimes they can be circular, hence 'circle packing'.

Hope this helps you out.

I also find that the best way to calculate reference points is by using a calculator and a ruler. It's a relatively simple process, but when doing it, it is absolutely necessary to use a centimeter ruler, because inches are divided into 16ths. You need to have base 10 to make the calculations correct.

So basically, all you need to do is first: Measure the side length of the square. Then measure the reference point(s). Once you have found out the distance, divide the distance that you measure by the side length of the square. Now you will have a decimal. Use the first 4 decimal points, and there you have it. A reference point.
Hope that helped.

What you need to find is the point marked in green here:


Afterwards you can make angle bisectors to get the blue diagonals and more angle bisectors to get the remaining lines needed.

To find this point measure the side length of the square and the distance of the point from a side and divide the distance through the length. Then add this number to Reference finder to get a folding sequence.

You can get Reference finder here: http://langorigami.com/science/reffinder/reffinder.php4

Anna, isn't the majority of this model based of a 26 by 26 grid? I counted, and I'm pretty sure it is.

Thanks so much for your help everyone!

So basically, you need to find the green point because that's where everything else, all the other angles, stem from?

Also, what does '(sqrt2+1):4:4:(sqrt2+1)' do? Is that the ratio of paper used? I don't really understand that bit.

(sqrt2+1):4:4:(sqrt2+1) is probably a reference to those four lengths between the green points:


To ted385:
I doubt that the CP is based on a regular grid, but probably it would be a good approximation.

Learn from this picture:



Now, if you want to use Reference Finder, you need to know what fraction of the side you want.

First you calculate the total length of the side: 1+√2+4+4+1+√2=10+2√2.

Then you find a point along the length. I would choose 2√2 or maybe 2*2√2=4√2 of the way down. In RefFinder this would be (10+2√2-4√2)=10-2√2, since the bottom left corner is (0,0)

So the points I would search for might be either ( [2√2]/[10+2√2] , 1 ) or ( 0 , [10-2√2]/[10+2√2] )


Also, while not totally accurate, here's a fairly close approximation for one of the points at the top:



EDIT: Since I'm a math major, I can't add. 4+4+1+1=10, not 8.

Oh I see now. Thanks, that was very helpful.

Thankyou everyone.

Are the lengths always proportional to a 45 degree right angle triangle?

All right, I did a little more work on it, and managed to guess this: