Sort by spatial resolution in a mosaic dataset

[niklasGregersen]

Hi Geonet users,

I am wondering if there is a way to sort my mosaic rasters, in my mosaic dataset, after their spatial resolution other than by manually selecting them and lock to those rasters. I have a sentinel 2 scene with raster products in multispectral (MS), 10m spatial resolution (MS-10), 20m spatial resolution (MS-20), and 60m spatial resolution (MS-60).

I have tried to use the sort by attribute function to select the different raster’s however the attribute referring to the different spatial resolutions (Tag) is not an available option. Is there a smart way to do this?

Thanks

[GünterDörffel]

Hi Niklas,

not sure how much you know about Mosaics – so sorry if this is too basic:

Actually, if you do not intervene, MosaicDatasets will always use the spatial resolution to decide which dataset to display.

This will be done by analyzing the content of the fields /[MaxPS] (this is the defined display range for the raster) – usually derived from /[HighPS] (this is the “physical” pixel size your data contains).

Now depending on how you added your data, the Sentinel dataset may be just one entry/record per dataset and handled INTERNALLY by ArcGIS. Or (this is what it seems to read in your question) you have several records for the different resolutions/bands? Then you could influence this behavior to meet the scales you want to see/use.

Just describe a little closer how you load the data and what you are trying to achieve?

Von: niklas Gregersen

Gesendet: Thursday, August 17, 2017 12:25 PM

An: Dörffel Günter <g.doerffel@mysynergis.com>

Betreff: - Sort by spatial resolution in a mosaic dataset

GeoNet <https://community.esri.com/?et=watches.email.thread>

Sort by spatial resolution in a mosaic dataset

created by niklas Gregersen<https://community.esri.com/people/niklasg@geoinfo.dk?et=watches.email.thread> in Imagery and Remote Sensing - View the full discussion<https://community.esri.com/message/708724-sort-by-spatial-resolution-in-a-mosaic-dataset?et=watches.email.thread>

[niklasGregersen]

Thanks a lot Günter!

I am new to using mosaic datasets, so it is perfect with a basic description. The description of how the mosaic dataset automatically selects the added rasters based on the MinPS and MaxPS range definitely helps. However, I have a little trouble understanding the MaxPS value compared to a scale in ArcGIS, e.g. what a MaxPS value of 1200 corresponds to in scale? Is that something I should find in the documentation for the satellites sensors? 

[GünterDörffel]

Hi Niklas,

the common definition of „scale” in a GIS is good to understand what you are looking at – but not really helpful if you ask yourself: “How is the raster(s) I use resampled? What “extent on earth” is represented by a pixel? That’s what the PixelSizes are about. Only when the geolocation and extent are known, the system can calculate (in the units of your coordinate system) how much “ground” is covered by a pixel.

See this help topic http://desktop.arcgis.com/en/arcmap/10.3/manage-data/raster-and-images/mosaic-dataset-attribute-tabl... for a general explanation. Or this for whats coming now: http://desktop.arcgis.com/en/arcmap/10.3/manage-data/raster-and-images/cell-size-ranges-in-a-mosaic-...

As mentioned above – lets say your original raster (not talking Sentinel now) has a resolution of 1m plus internal pyramids by the factor of 2 for 3 levels, that would be 2m, 4m and 8m then … Your mosaic dataset would show

LowPS 1

High PS 8

And the and values would now state at which “pixel size scales” these rasters are suitable for display. By default the factor used will be something like 10 – and since you can zoom all the way in, the start would be at 0

MinPS would be 0

MaxPS would probably be 80

Saying that as long as one pixel on the map represents between 0m and 80m, this dataset might be used.

If you’d create overviews now they’d make sure the data can be used “above” 80m per Pixel.

To find out what that means in terms of “map scale” – its explained in the second link above and could be complicated especially when your coordinate system is decimal degree

MODIFIED 2017/08/18 - previous link removed

I have made an Excel to help you get an idea years ago and updated since I found out it did not work with 10.5 and Pro. Should be self explanatory.
Find attached as PS2Scale_2017.zip

You can help yourself in the GUI by adding PixelSize information to your TOC:

In the Display-Tab of a Mosaic … in ArcMap:

[see attached image 1]

And that will display the current cellsize to you:

[see attached image 4]

In Pro I haven’t found that one yet

Regards

Guenter

[niklasGregersen]

Thanks a lot, it is indeed very helpful  

[CodyBenkelman]

Niklas:

there are very many settings of the Mosaic Dataset.  It has a great deal of power but you'll need to learn what they mean and how to use them.  The help documentation is good, and our Image Management Workflows at http://esriurl.com/ImageManagement provide valuable advice.  

Cody