Faster way to mosaic rasters

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07-17-2014 01:10 PM
New Contributor III

Hey all,

I have a number of Global Forest Watch raster tiles that I need to reproject and mosaic quickly. So far I have been using the Mosaic to New Raster tool to accomplish both tasks in one step, however it takes a whopping +30 minutes for me to mosaic and reproject just two raster tiles. Is there a way in which this could be accomplished faster, either by using a different tool or by getting the Mosaic to New Raster tool to process faster? If done separately, it takes about the same time (about 4-5 minutes to reproject an individual raster tile, and 15 minutes to mosaic them together).

I have also tried the method of creating a raster catalog and then turning the catalog into a raster dataset, but I was wondering if there was a way that required less steps/less files created for the inbetween phases.

Thanks,

P

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Esri Contributor

Piyali,

Mosaic datasets are the way to go. You specify the projection of the MD. Regardless of the image projection. You then load the imagery to the MD. The MD will record metadata information and footprints about each image but leaves the image on disk. Finally you create overviews, which are effectively pyramids over the entire seamless image dataset. Overviews are what give the MD it's speed. If you do not make overviews then you will not see the image layer until you are at an optimal scale to display the image pixels

it is usually a quick process To create MD's and they perform well when created correctly.

Gordon

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MVP Esteemed Contributor

In other threads, a Mosaic Dataset is recommended rather than mosaicking them all

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New Contributor III

Hi Dan (and Timothy Hales ),

I tried using a Mosaic Dataset today, and I'm a bit confused. It seems like it doesn't doesn't display the actual rasters that I loaded into it (the "Image" category is basically irrelevant, as it's not displaying the data). Do I treat the mosaic dataset as I would a newly mosaic-ed layer? As in, when I go to tabulate areas, would I drag the mosaic dataset into the tool and it will tabulate the area of the zone like a normal raster layer?

Or do I need to project my rasters before loading them into the mosaic dataset? (I thought we are allowed to change the projection within the Create Mosaic Dataset tool.)

Thanks for your help!

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Esri Contributor

Piyali,

Mosaic datasets are the way to go. You specify the projection of the MD. Regardless of the image projection. You then load the imagery to the MD. The MD will record metadata information and footprints about each image but leaves the image on disk. Finally you create overviews, which are effectively pyramids over the entire seamless image dataset. Overviews are what give the MD it's speed. If you do not make overviews then you will not see the image layer until you are at an optimal scale to display the image pixels

it is usually a quick process To create MD's and they perform well when created correctly.

Gordon

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Esri Notable Contributor

I agree with Dan. A mosiac dataset is much more efficient, especially when it comes to storage and processing speed.

Also, I've moved your post into the Managing Data space. You will get a much better answer here as the GeoNet Help is intended for community help and feedback. You can see more on the community structure, and what topics are under each space from the following documents:

GeoNet Community Structure

ArcGIS Discussion Forums Migration Strategy

Thanks!

Timothy

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