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Thread: Caching Tiles In Mosaic Dataset

  1. #1
    Ömer KAYA
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    Exclamation Caching Tiles In Mosaic Dataset

    Hello All;

    I am trying to create cached tiles for an Image Server.

    My data source is Mosaic Dataset.

    Is there a documentation? where can i produce 256*256 PNG tiles to serve?

    How can i do it?

    Kind Regards

    ömer

  2. #2
    melanie harlow
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    Default Re: Caching Tiles In Mosaic Dataset

    You cannot create a cache directly from a mosaic dataset or image service in 10.0. But you can generate a cache on a map service or globe service. Therefore, you need to add your image data (either the source dataset, such as the mosaic dataset or raster dataset, or an image service) to the map or globe document and serve the document. You are then able to use the caching tools to generate a cache. (As stated within Caching image data)

    However, when using a mosaic dataset, even in a map document the ArcGIS Server Image Extension is required.

    Learn about planning a map cache

  3. #3
    Gordon Sumerling
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    Default Re: Caching Tiles In Mosaic Dataset

    As a follow-up to Melanie's comments, at 10.1 you will be able to cache an Image Service directly with ArcGIS Server.
    However, before you go ahead and cache an Image Service/Mosaic Data set it is important that you consider what advantages it gives you. An image service based on a Mosaic dataset is already quite fast. It returns what you need at the extents you need it. If you cache an image service you effectly double the amount of diskspace required to store the images. Once for the image source and once for the Cache. Do you have this amount of space available. Finally, how much more speed will the cache of an image service give me. In most cases between 5 and 10%. Will your end users notice this extra speed and is it worth the extra disk capacity required?

    Hope this helps you with your caching strategies

    Cheers
    Gordon
    Gordon Sumerling
    Esri Australia

  4. #4
    Joe Flannery
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    Default Re: Caching Tiles In Mosaic Dataset

    Gordon: Thank you for your comments regarding mosaic datasets and image services. I am trying my first mosaic dataset/image service in an Amazon EC2 instance and testing it against a cache service on the same server. Do you have any advice regarding “optimizing” a mosaic dataset for use in an image service? Here is what I have done in ArcGIS 10.1 prerelease.

    Convert imagery from TIF to Jpeg2000 (UTM coord sys)
    Create file geodatabase
    Create Mosaic Dataset (Web Merc coord sys)
    Add Rasters to Mosaic Dataset (JP2 files)
    Define Overviews (location = FGDB)
    Build Overviews (1280x1280 rows; Sampling Factor = 2)
    Set “Mask” and “Stretch” Mosaic Functions
    Publish Mosaic Dataset to Image Service

    Am I missing anything important?
    Thank you for your time.
    Sincerely,
    Joe
    Joe Flannery

  5. #5
    Gordon Sumerling
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    Default Re: Caching Tiles In Mosaic Dataset

    Joe,

    The first issue I see here is you have converted your tiffs to JP2. Although we support JP2's we recommend Tiff, with JPEG compression of 75%. JP2's are actually computationally more expensive and so can be slower to decompress and dynamically mosaic when reaching the native pixel level or any time you access the internal pyramids of the native imagery.

    The second item I see here you have defined the storage location of your overviews to be in the FGDB. I would recommend the actually be stored on disk as tiffs. Again for speed.

    The final thing I would suggest is that you build pyramids on the native tiff images. This provides higher acccess speeds when you reach the image display level. Remeber pyramids are internal to the native image while overviews are aexternal and cover the entire image mosaic.

    Hope this helps.
    Gordon
    Gordon Sumerling
    Esri Australia

  6. #6
    Joe Flannery
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    Default Re: Caching Tiles In Mosaic Dataset

    Gordon:

    Thank you for the helpful directions. I converted the 100's of gigabytes of TIFs to jpeg2000 files to save storage space on the server (about 85% savings). I will test your process and also talk to IT about more server space.

    Thanks again for your thoughts and time.
    Joe
    Joe Flannery

  7. #7
    gaurav narang
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    Default Re: Caching Tiles In Mosaic Dataset

    The caching process sometimes creates blank and/or white tiles when using Mosaic datasets. When this happens no error is reported in the server log because the tiles are actually created in the cache folder but are white in color.

    Consider increasing the 'Maximum Number of Rasters per Mosaic' value to higher number so that all the images are visible for the required extent in the caching process.

    Refer below url link for more information:
    http://support.esri.com/en/knowledgebase/techarticles/detail/39255

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