From: Gökçen G. <gok...@gm...> - 2013-01-11 12:21:31
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Using JAI was not my decision, I couldn't find a JAI-free Geotools solution for this as I said in my first post. I'll be glad to hear it. 2013/1/11 Ian Turton <ijt...@gm...> > As far as I can see your problem is that you decided to use JAI directly > instead of calculating NDVI using the GeoTools raster classes that would > have maintained the location of the data. JAI is an image processing > solution and as such throws away all the geography in the data - then > GeoTools is unable to import the image because it doesn't know where it is. > > Ian > > > On 11 January 2013 11:37, Gökçen Güner <gok...@gm...> wrote: > >> Thank you so much guys. I didn't have much time at that time so I >> switched from Geotools to Grass, I'm not familiar with Python as much as >> Java but it has more features on programming side. >> >> Besides I couldn't use geotools effectively, I think some native >> implementation required this image processing thing. It shouldn't be so >> hard to subtract an image from another. You just do it pixel by pixel, you >> have same geocode in both files, preserve them and write it to the new >> file, it is just easy as that. I looked at JAI related posts, 9 of 10 >> people say 'don't use it'. I looked at Geotools posts or tutorials, they >> all use JAI. Geotools must find a way to get rid of JAI in my opinion. >> >> It is not directly about geotools, it is about Java for sure but any GIS >> framework should have a some way to do this. In Grass, they bridged >> functionalities of Grass to Python, you import the classes(modules in >> Python) and you are good to go. In image processing, C/C++ has more >> popularity in comparison with Java but using JNI it can be dealt with I >> think. It is not well documented you can say, it's hard do debug or test >> you can say but it should be considered as a solution. Coded with JNI, >> proposed as a Java class and users will use it. >> >> As a Java developer and fan(it is fun to code with java), I felt >> disappointed when I realized that in Java we don't have so many choices in >> GIS. Geotools still seems to be best but considering its competitors I >> think more work is needed. >> >> Thanks for making time to read this. >> >> 2013/1/10 Rafael Santos <raf...@in...> >> >>> Hi, >>> > I need to find NDVI and other vegetation indices and then find changes >>> > in time with tif images. >>> > >>> > I've been using Geotools for this. Took 2 tiff images, then using QGis >>> > I changed them to PNG because original ones are huge. Then taking >>> > those 2 PNG I created NDVI image using JAI. The problem is that I >>> > couldn't show this file with Geotools. You can look at the code here: >>> That code creates a TIFF with floating point pixels, which can be >>> loaded/viewed with DisplayNBImage since DisplayNBImage internally >>> creates a byte-based surrogate version of the floating-point image. If >>> your purpose is just to display the image why not create a byte-based >>> one? >>> >>> > >>> > In fact, proposing non-Jai way of the same thing would be awesome. >>> > >>> If you don't mind having a byte image that should be simple. Open both >>> images, declare a matrix of the appropriate size of type float, >>> calculate the NDVI for each pixel, create a temporary byte image and >>> populate it with the values from the matrix, properly normalized. Some >>> steps for this are on >>> >>> http://www.lac.inpe.br/JIPCookbook/1200-create-gl.jsp#imageanddatamanipulationcreatinggraylevelimages >>> . Two caveats: I am not sure if plain Java have readers for TIFF images >>> (in case your original images are TIFFs) and the original NDVI values >>> will be of course gone -- not an issue for visualization/comparison. >>> >>> hope it helps >>> >>> Rafael >>> >>> >>> >>> >>> ------------------------------------------------------------------------------ >>> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, >>> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current >>> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft >>> MVPs and experts. ON SALE this month only -- learn more at: >>> http://p.sf.net/sfu/learnmore_122712 >>> _______________________________________________ >>> GeoTools-GT2-Users mailing list >>> Geo...@li... >>> https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users >>> >> >> >> >> ------------------------------------------------------------------------------ >> Master HTML5, CSS3, ASP.NET, MVC, AJAX, Knockout.js, Web API and >> much more. Get web development skills now with LearnDevNow - >> 350+ hours of step-by-step video tutorials by Microsoft MVPs and experts. >> SALE $99.99 this month only -- learn more at: >> http://p.sf.net/sfu/learnmore_122812 >> >> _______________________________________________ >> GeoTools-GT2-Users mailing list >> Geo...@li... >> https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users >> >> > > > -- > Ian Turton > |