Thanks Ian for link, looking at Operations and this link:
http://docs.geotools.org/stable/javadocs/org/geotools/coverage/processing/operation/package-summary.htmlI've
found some way to go. My thoughts on 2nd post still same though. These
seems wrappers around JAI functionalities as Javadoc says the same. I think
geotools should draw a path away from JAI, you can read about it and see
why people are suggesting to avoid using it.
2013/1/11 Ian Turton <[email protected]>
>
>
>
> On 11 January 2013 12:21, Gökçen Güner <[email protected]> wrote:
>
>> 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.
>>
>>
>> But you didn't use GeoTools for that bit - the fact that JAI is in
> GeoTools is irrelevant to your code. Have a look at
> http://docs.geotools.org/latest/userguide/library/coverage/grid.html to
> see how to handle raster data in GeoTools.
>
> Ian
>
>
>> 2013/1/11 Ian Turton <[email protected]>
>>
>>> 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 <[email protected]> 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 <[email protected]>
>>>>
>>>>> 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
>>>>>
>>>>>
>>>>>
>>>>>
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>>>>
>>>>
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>>>
>>>
>>> --
>>> Ian Turton
>>>
>>
>>
>
>
> --
> Ian Turton
>
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