Hello world! This is my first post about GSoC. I usually write post to this blog using Indonesian language so people who are from Indonesia can easily understand and also to contribute to probably technical corpora which is written in Indonesian. For the next posts that will be using gsoc2013 tag also will be written in English.
Now, a little bit of background won’t hurt.
This is my first experience in Google Summer of Code, applying and being accepted. My last status as student was 2010 which is almost three years ago. Now that I am back as student, I am eligible to apply as participant. Yay!
The project I am working on is under the organization of Computational Science and Engineering of Vienna University of Technology. Altough I am also a student in TU Wien, The Mentors are from different institute. My Mentors are from Department of Geodesy and Geoinformation. The project itself is implementing transformation algorithm for vertical datums. For me, this is something that is quite new. I did projects using spatial data before, but the inner working of the knowledge behind that was actually done by another person which background is geodesy. Well, the availability of libraries like PROJ.4, GDAL/OGR really helped me a lot back then. That’s why I thought this might be the way I can contribute back.
The project itself was also offered as GSoC project last year, but for some reasons it was cancelled. So now I am gathering information about the status of the last project and trying to update the codebase to use latest version of the libraries. At that time, GDAL/OGR version that is used was still 1.9.1 while current version is 1.10.0. It’s has been two releases since so there are some changes.
The project itself is a little bit complicated because of it’s nature and inherent dependencies. In GDAL/OGR, the transformation of coordinates are done by PROJ.4 library, while for doing vertical transformations some data to support the transformation is supplied via raster files. So what I will do in this project is to load those data using GDAL/OGR and also implementing a subset of coordinate transformation. Now the usual way PROJ.4 is used by GDAL/OGR. But in this case, there’s also need to transform the 3D coordinates but the information is supplied via functionalities in GDAL/OGR therefore creating a cyclic dependency. The way to solve it that we agreed was to create redundancy by duplicating some of coordinate transformation code in PROJ.4 into a new module in GDAL/OGR so the only thing that should be maintained is the modified GDAL/OGR code base.