How to generate the basis from 2D invariant points of a model?

[jemimaloh]

I'm doing a project on geometric hashing. Of which i am unsure about the basis generation (meaning, finding only a pair coordinates that coincide with the X-axis) from all the invariant points in the coordinate file of a given 2D model which would have been hashed already. This case being, we could also orientate the model in space further, so that all 2D models in the database can be automatically go through an appropriate offset.

Your help is greatly appreciated.

[NormR1]

Do you have the algorithm that you want to write in Java?
Once you get that, someone can help you with your problems coding it.

[jemimaloh]

Yups. Geometric hashing is the algorithm that i am using.
There's a preprocessing and a recognition phase.

preprocessing:

var
Mu the Model structure
H the hash table
F the hash function
Pl the label of atom Ap

begin
for each model Mu
do
for each (ordered, noncollinear) triple (ai, ak,ar) extracted from Mu
do calculate the reference frame Rikr
for each atom p extracted from Mu
do calculate F = F (Rikr, Ap, Pl);
H(F)U(Mu, Rikp)
end
end
end
end

recognition phase:

Compare the query structure with each model structure in the hash table
var
v two-dimensional vote table
H the hash table
F the hash functiion
qL the label of atom Aq
M the model structure
R a reference frame

begin
repeat
initialize the vote table V to 0
choose 3 atoms (Bj, Bl, Bs) in the query as basis,
defining the reference frame Rjls
for each atom q in the query do
calculate F = F(Rjls, Bq, Ql)
for each pair (M, R) in reference H(F)
do V ( M, R) := V(M, R) + 1
end
until satisfactory conincidence set is found or all queries ref. frames are used.
end

Excerpt from Protein bioinformatics: an algorithm approach to sequence and structure analysis I. Eidhammer, I.Jonassen, and W.R. Taylor copyright 2004 John Wiley & Sons, Ltd ISBN: 0-470-84839-1

If anyone could even explain to me just a segment of it, I'll be really really grateful. Thanks!

[NormR1]

You're going to have to make some effort to code it.
For example what is the code for this statement:
do calculate F = F (Rikr, Ap, Pl);
or this:
calculate F = F(Rjls, Bq, Ql)
or this:
do V ( M, R) := V(M, R) + 1

[Taywin]

You do not understand how the algorithm go or you do not understand how to apply Java to it??? If you do not understand the algorithm, you could look at wikipedia. If you do not know how to apply Java to the algorithm, that may need a little more work for you.

[jemimaloh]

I don't know how to apply java to it but i am quite sure that i understand the algorithm cause I've read 20 over PDFs on it..