A Curious Animal

Ptolemy goal is to build a good virtual globe SDK (open source project of course), easy to use and to extend by anyone.

The current version has some serious design problems and complex code which makes difficult to understand and extend for anyone who wants to contribute. Because this, recently Ptolemy project authors has started a period or re-foundation to build the project again from scratch.

The goal of re-foundation project are:

• Use a new working methodology (more agile).
• Improve the project documentation.
• Make a new implementation from scratch.

After that, we want to have a basic Virtual Globe SDK with a good design, implementation and documentation and, of course, stable enough to be used in any production environment :)

This way contributors will present their ideas, they will be discussed (using chat, email or Ptolemy group) and finally they will be briefly documented or explained and implemented.

In the next link you can follow the evolution of this amazing stage of the project: Ptolemy Refoundation.

As always you are welcome to participate actively.

I would like to have written this post some time ago but time is not something I have in exces.

This post starts when my friend Johann let me know the creation of the GeoToolkit project, a fork of GeoTools, started by one of the originals GeoTools authors. Take a look at project's history to know more details about the reasons.

Next is a simple example showing how to reproject coordinates from WSG84(EPSG:4326) to EPSG:3068 that, for those interested, I used in a program to render CityGML files in a Java 3D viewer called pTolemy3D.

public static boolean translate(GeneralDirectPosition source, GeneralDirectPosition target) { CRSAuthorityFactory factory = AuthorityFactoryFinder.getCRSAuthorityFactory("EPSG", null); try { ProjectedCRS projSource = factory.createProjectedCRS("3068"); GeodeticCRS projTarget = factory.createGeographicCRS("4326"); // NOTE: This is another way to create the right projection: // ProjectedCRS proj = (ProjectedCRS) CRS.decode("EPSG:3068"); // System.out.println("Orig: " + projSource); // System.out.println("Target: " + projTarget); MathTransform transform = CRS.findMathTransform(projSource, projTarget); // System.out.println("Transform: " + transform); try { transform.transform(source, target); return true; // System.out.println("Point Source: " + psource); // System.out.println("Point Target: " + ptarget); } catch (MismatchedDimensionException ex) { Logger.getLogger(GeoUtil.class.getName()).log(Level.SEVERE, null, ex); } catch (TransformException ex) { Logger.getLogger(GeoUtil.class.getName()).log(Level.SEVERE, null, ex); } } catch (NoSuchAuthorityCodeException ex) { Logger.getLogger(GeoUtil.class.getName()).log(Level.SEVERE, null, ex); } catch (FactoryException ex) { Logger.getLogger(GeoUtil.class.getName()).log(Level.SEVERE, null, ex); } return false; }

Not so much, but hope it will be useful for someone and hope more users start to use GeoToolkit.

Some days ago I saw this post, from Ron Lake's blog, in the Planet Geospatial.

As Ron says, ...In common parlance, and in land surveying, a datum is a reference point or reference surface.  Sometimes this is also interpreted as the zero point for a measurement... but ...provide a poor basis for generalization...

Datum – What’s in a name?

Enjoy it !

Some days ago I read a post related to the citygml4j project. As its web page says:

citygml4j is a Java class library and API for facilitating work with the City Geography Markup Language (CityGML). citygml4j makes it easy to read, process, and write CityGML datasets, and to develop CityGML-aware software applications.

A couple of days ago I downloaded the binary package and try to execute some samples. Unfortunately it was compiled using Java6 and I was using Java.5 because I need it for my current project.

I wrote an email to Claus Nagel, the project manager,  talking about my "problem" and (wow) a couple of hours after, Claus has published a new binary package ready to use with Java1.5.

I only have congratulation words for you Claus ;)

Today I found, via the spanish blog La Cartoteca, this nice post about projections in the NextNature web site.

The video, which I also attach here, show how 3D globe can be represented in a 2D space.