Update readme

README.md

@@ -1,21 +1,33 @@
 # d3-spring-model
 
-This module implements Chalmers' 1996 Neighbour and Sampling algorithm for drawing the force-directed layouts. It is a linear time algorithm that uses stochastic sampling to find the best neighbours for high-dimensional data and creates the layout in 2 dimensions.
+This module implements three force-directed layout algorithms to visualize high-dimensional data in 2D space.
+1. Basic spring model algorithm. In this model, every data point (node) pairs are connected with a spring that pushes or pulls, depending on the difference between 2D and high-dimensional distance. This is a tweaked version of [D3's force link](https://github.com/d3/d3-force#forceLink) with functionalities removed to improve performance and lower the memory usage.
+1. Neighbour and Sampling algorithm. It uses stochastic sampling to find the best neighbours for high-dimensional data and creates the layout in 2 dimensions.
+1. Hybrid layout algorithm. It performs Neighbour and Sampling algorithm on a subset of data before interpolating the rest onto the 2D space. Neighbour and Sampling algorithm may also be run over the full dataset at the end to refine placement.
+During the interpolation, each node have to find a parent, a closest node that has already been plotted on the 2D space. Two methods of of finding the parents have been implemented.
+   1. Bruteforce searching. This method takes more time but guaranteed that the parent found is the best one.
+   1. Pivot-based searching. This method introduce a one-off pre-processing time but will make parent finding of each node faster. The parent found may not be the best one but should still be near enough.
 
-Neighbour and Sampling algorithm is useful for producing visualizations that show relationships between the data. For instance:
+These algorithms are useful for producing visualizations that show relationships between the data. For instance:
 
-![fsmvis data set](https://raw.githubusercontent.com/sReeper/d3-neighbour-sampling/master/img/chalmers-fsmvis.PNG)
-![Poker Hands data set](https://raw.githubusercontent.com/sReeper/d3-neighbour-sampling/master/img/chalmers-poker.PNG)
+![Iris data set](img/IrisLink.png)
+![Part of Poker Hands data set](img/Poker3000Link.png)
 
 ### Authors
-Remigijus Bartasius and Matthew Chalmers
+Pitchaya Boonsarngsuk
+
+Based on [d3-neighbour-sampling](https://github.com/sReeper/d3-neighbour-sampling) by Remigijus Bartasius and Matthew Chalmers under MIT license.
+
+Based on [d3-force](https://github.com/d3/d3-force) by Mike Bostock under BSD 3-Clause license.
 
 ### Reference
-- Chalmers, Matthew. ["A linear iteration time layout algorithm for visualising high-dimensional data."](http://dl.acm.org/citation.cfm?id=245035) Proceedings of the 7th conference on Visualization'96. IEEE Computer Society Press, 1996.
+- Chalmers, M. ["A linear iteration time layout algorithm for visualising high-dimensional data."](http://dl.acm.org/citation.cfm?id=245035) Proceedings of the 7th conference on Visualization'96. IEEE Computer Society Press, 1996.
+- Morrison, A., Ross, G. & Chalmers, M. ["A Hybrid Layout Algorithm for Sub-Quadratic Multidimensional Scaling."](https://dl.acm.org/citation.cfm?id=857191.857738) INFOVIS '02 Proceedings of the IEEE Symposium on Information Visualization, 2002
+- Morrison, A. & Chalmers, M. ["proving hybrid MDS with pivot-based searching."](https://dl.acm.org/citation.cfm?id=1947387) INFOVIS'03 Proceedings of the Ninth annual IEEE conference on Information visualization, 2003
 
 ## Usage
 
-Download the [latest release](https://git.win32exe.tech/brian/d3-spring-model/releases) and load one of Javascript file alongside [D3 4.0](https://github.com/d3/d3).
+Download the [latest release](https://git.win32exe.tech/brian/d3-spring-model/releases) and load either the full and minified version alongside [D3 4.0](https://github.com/d3/d3).
 ```html
 <script src="https://d3js.org/d3.v4.min.js"></script>
 <script src="d3-spring-model.min.js"></script>