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Gary, Thank you for the hint. I've noticed your great work since your first project released on github, Tinfour, and more recently gridfour. I'm always excited when I see successful gis opensource contributions in java. I'm not the best expert about raster data in openjump team, but I've already used images converted to cog geotiff (with cogeo) in another context, to optimize image display in QGIS. It is good news to know such capabilities exist in pure java with commons-imaging. My experience was only in a desktop context, so I think QGIS takes advantage of the presence of subsampled overviews in the file. I don't know if it can also take advantage of the tiled structure of images to avoid reading the full file. AFAIK, openjump does not take advantage of image overviews, tiled layout or anything like this, but it would be of great interest. I had a very quick look at your DemoCOG example, but I did not see any specific code to take advantage of overviews or tiled structure. Maybe I must read it more attentively, or maybe the code is more to demonstrate metadata/georeferencing reading and elevation data/shaded relief rendering. Michaël
envoyé : 12 octobre 2020 à 05:28
de : Gary Lucas <gwluca...@gmail.com>
à : jump-pilot-devel@lists.sourceforge.net
objet : [JPP-Devel] Reading elevation data using Apache Commons Imaging
I first heard about OpenJUMP last month when one of your users posted a bug report on the Apache Commons Imaging JIRA system (see https://issues.apache.org/jira/browse/IMAGING-265). The bug is fixed now and I am grateful for the folks here who brought it to my attention. Anyway, based on that posting, and some of the JPP documentation, I get the impression that Commons Imaging is used in at least some capacity in OpenJUMP. So I thought that I would mention another relatively new feature in the Commons Imaging API: the ability to read floating-point elevation data from USGS 3DEP Cloud-Optimized GeoTIFF files. This capability was introduced in the latest release of Commons Imaging (commons-imaging-1.0-alpha2). I don’t know if it is something the project can take advantage of, but I thought I would bring it to your attention. If you would like more information on the feature, I’ve just posted an article and some sample code showing how to use the API for creating shaded-relief imagery. While OpenJUMP already has its own shaded-relief capability through its Sextante plugin, I think that the article might be of interest to folks on this mailing list because it provides background on the USGS GeoTIFF files as well as discussing the algorithms for shaded-relief rendering. If you are interested, you may access it at https://gwlucastrig.github.io/gridfour/notes/ElevationGeoTiff1.html Thanks, and good luck on the JUMP Pilot Project. It is an impressive project and I look forward to studying it further. Gary
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