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avalentino / gsdview

Lightweight Geo-Spatial Data Viewer (GSDView) written in python and Qt. It uses the GDAL library for data access, it is modular and has a simple plug-in architecture.
GNU General Public License v2.0
25 stars 8 forks source link

Actively maintained? #92

Open piyushrpt opened 8 years ago

piyushrpt commented 8 years ago

Hi Antonio, This is not really an issue but more of a question. I noticed the recent set of extensions to GDAL VRT's format that is very relevant for SAR/InSAR processing. ISCE InSAR software from JPL will generate VRT files by default for all products in future releases. I was wondering if gsdview would make a good replacement for mdx, since it appears to have all the same features. Is gsdview still actively maintained?

Thanks Piyush

avalentino commented 8 years ago

Hi @piyushrpt, I try to ensure basic maintenance and bug fixing. Also, I have a couple of new features in the pipeline but I have not a schedule for that.

Of course anyone wanting to join the project or simply submitting pull requests for enhancements or bugfix is very welcome.

P.S.: I don't know mdx, it seems that a password is needed to download it. Which are exactly features you are interested in?

piyushrpt commented 8 years ago

mdx is a "load on scroll" visualization program that is used by radar groups in the US for visualiztion. It is also included as a part of the ISCE package. Its strength is that any point of time it only loads the part of data that is visible to the user and adds new data to canvas as the user scrolls. This allows it to show large images (many GB) without the need to pre-render anything. I believe openev (using GDAL) was like this, and from playing around a little bit with gsdview it appears to be similar. Is that correct?

MDX also performs similar stats computations like gsdview (on overviews) to scale the images before display. MDX includes features like plotting profiles and it looks like gsdview can potentially do more including histograms etc. Problem with mdx is that it can only handle flat binary files and is written in fortran (making it hard to add support for other formats). Moving to something like gsdview (or openev) will allow for support for more formats.

The new pixel function features for complex data makes GDAL VRTs more suitable for what we are trying to do. Hence, wondering if gsdview is a good starting point for thinking about replacing mdx. If it works the same way "load on scroll", would be happy to start contributing to this effort.

Piyush

avalentino commented 8 years ago

Correct gsdview performs an initial computation of statistics and overviews, and then it only loads the portion of data exposed by the viewport. It loads data tiles with the correct resolution level to avoid large memory requirements when the user zooms out, but ensuring the correct level of detail. gsdview exploits the gdal tile caching machinery to make the all process very efficient.

If it works the same way "load on scroll", would be happy to start contributing to this effort.

Happy to hear it :)