Re: [udig-dev] uDig Data Structures

[Jody Garnett <jody.garnett@xxxxxxxxx>]

I was hoping if (one of the) uDig developers could answer the following questions:
 -  What is/are the main data structure(s) used by uDig (e.g., GIS-grid or something like that).

There is a difference between data structure and data model. The data model we make use of comes from the GIS domain. Because we are lazy we make use of all the names provided by the industry standards body called the Open Geospatial Consortium (OGS) - this is easier for communication then doing modelling on our own. 

Have a look at the OGC Reference Model - it introduces ideas like "feature", "coverage" and "feature type".

 

 - Are there multiple implementations for that data structure (e.g., for java.util.List we see Vector, ArrayList and LinkedList).

Yes - by definition (it is a standard for interoperability). Even within uDig the GIS library we use (called GeoTools) implements "FeatureCollection" again and again for each data format capable of storing features.

 

 - What are the algorithms (or type of algorithms) applied to these data structures?

I guess they would be spatial algorithms, here is a link to JTS (vector) JAI Tools (raster) and JGrassTools (scientific) for examples of libraries we use.

 

 - Is uDig used sometime with (large) data sets that cause the program to run (more) slow?

Yes, GIS data is big (so big we avoid loading it into memory as a rule).

 

Thanks in advance,

Mattias De Wael




--
Mattias De Wael
Vrije Universiteit Brussel
Faculty of Sciences, DINF - SOFT
Room 10F719, Pleinlaan 2, B-1050 Brussels, Belgium
e-mail: madewael@xxxxxxxxx

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